Metabolic Health

a vital biomarker used to evaluate hormonal health

What is % Free Testosterone (Dialysis)? % Free Testosterone (Dialysis) measures the percentage of total testosterone in your bloodstream that is not bound to proteins like sex hormone-binding globulin (SHBG) or albumin. This test uses a dialysis-based method, which is considered the gold standard for accurately quantifying free testosterone — the biologically active form of the hormone. In your blood, most testosterone is attached to proteins, which helps transport it through your body. But only a small fraction — known as “free testosterone” — is unbound and bioavailable, meaning it can directly interact with cells and carry out essential hormonal functions. The “percent free testosterone” tells you how much of your total testosterone is in this usable, free form. Why is % Free Testosterone Important? Free testosterone plays a critical role in regulating: Libido and sexual function Muscle mass and strength Bone density Mood and cognitive performance Red blood cell production Fat distribution and metabolism A normal percentage of free testosterone ensures that your body is able to respond appropriately to hormonal signals, especially in tissues like the brain, muscles, and reproductive organs. It’s particularly useful when total testosterone levels are borderline or when symptoms suggest a hormone imbalance. What is the Dialysis Method? The equilibrium dialysis method separates free testosterone from protein-bound forms by using a membrane that mimics the way substances naturally pass through cell membranes. This is a highly sensitive and specific method that directly measures the actual free testosterone, unlike some calculations or indirect methods (like analog-based assays) that may produce inaccurate results, especially in individuals with abnormal SHBG levels. What Do Abnormal % Free Testosterone Levels Mean? Elevated % Free Testosterone A higher-than-normal percentage of free testosterone may indicate: Polycystic Ovary Syndrome (PCOS) in women Androgen-secreting tumors (rare) Congenital adrenal hyperplasia (CAH) Steroid use or abuse Low levels of SHBG (common in obesity, insulin resistance, or hypothyroidism) Decreased % Free Testosterone A low percentage of free testosterone may suggest: Male hypogonadism (low testosterone production) Aging-related testosterone decline Chronic illness or stress Elevated SHBG (can occur with liver disease, hyperthyroidism, or estrogen therapy) Obesity or metabolic syndrome Even if your total testosterone level is in the normal range, your free testosterone could be low — and that’s often when symptoms appear. Who Should Get This Test? This test is often ordered when someone has symptoms of testosterone imbalance but a normal or borderline total testosterone level. It is especially useful for: Men with signs of low testosterone (fatigue, low libido, depression, muscle loss) Women with signs of high testosterone (acne, hirsutism, irregular periods) Individuals with abnormal SHBG levels Monitoring response to testosterone replacement therapy (TRT) Evaluating hormonal health in aging men or athletes What’s a Normal % Free Testosterone Range? Reference ranges can vary by lab, but typical values are: Men: 1.5% – 3% of total testosterone Women: 0.3% – 1.9% of total testosterone These values should always be interpreted alongside total testosterone, SHBG, and your clinical symptoms. Final Thoughts Testing % Free Testosterone by Dialysis offers a more precise understanding of your hormone health than total testosterone alone. It helps identify subtle hormone imbalances that might otherwise be missed — especially when protein-binding changes are involved. If your results are abnormal, follow up with a healthcare provider to investigate further and discuss treatment or lifestyle strategies.

1,5-Anhydroglucitol (1,5-AG) is a monosaccharide that plays a critical role as a biomarker in the assessment of intermediate glycemic control in individuals, particularly those with diabetes. Unlike conventional markers such as glycated hemoglobin (HbA1c), which reflects average blood glucose levels over a period of approximately two to three months, 1,5-AG offers a more immediate view of glycemic control, usually reflecting fluctuations in blood glucose levels over a shorter period of one to two weeks. This distinct temporal sensitivity arises from its unique physiological mechanism: 1,5-AG is typically maintained at a constant level in the bloodstream, but when blood glucose levels rise above the renal threshold (approximately 180 mg/dL), glucose competes with 1,5-AG for reabsorption in the kidneys. As a result, elevated blood glucose levels lead to an increased excretion of 1,5-AG in urine, thereby reducing its serum concentration. This biomarker's sensitivity to short-term glycemic excursions makes it particularly useful in detecting and monitoring postprandial hyperglycemia and glycemic variability, both of which are significant factors in the pathogenesis of diabetic complications and may not be adequately captured by HbA1c alone. Consequently, 1,5-AG serves as a valuable adjunct to HbA1c in providing a comprehensive picture of glycemic control. It is particularly beneficial in situations where HbA1c readings may be misleading, such as in cases of hemoglobinopathies, recent changes in diabetes therapy, or pregnancy. Moreover, the assessment of 1,5-AG levels can be instrumental in guiding therapeutic adjustments in diabetes management, aiming for a holistic approach to the control of both fasting and postprandial blood glucose levels. However, it's important to note that the interpretation of 1,5-AG levels must be done cautiously, considering factors like renal function, as renal impairment can affect its accuracy as a glycemic marker. Reference Range(s): Age Male (mcg/mL) Female (mcg/mL) ≤1 year Not established Not established 2-17 years 15.0-38.0 11.2-35.7 ≥18 years 7.3-36.6 7.5-28.4

predominant form of Folate in plasma

AC/FC, which stands for Acylcarnitine to Free Carnitine ratio, is an important marker used in the assessment of metabolic health, particularly in diagnosing and managing metabolic disorders related to fatty acid metabolism. Carnitine is a vital molecule that helps transport fatty acids into the mitochondria, the energy powerhouses of cells, where they are broken down to produce energy. The AC/FC ratio reflects the balance between acylcarnitines, which are fatty acids bound to carnitine, and free carnitine, which is available for further transport activities. This ratio can provide insights into how efficiently the body is processing and utilizing fatty acids. When the AC/FC ratio is elevated, it may indicate that there is an accumulation of acylcarnitines, suggesting a potential block or inefficiency in the fatty acid oxidation pathway. This could be due to various inherited metabolic disorders such as medium-chain acyl-CoA dehydrogenase deficiency (MCADD) or other conditions affecting mitochondrial function. Conversely, a low ratio might indicate a shortage of acylcarnitines, which could imply an issue with the initial step of fatty acid transport into the mitochondria. Monitoring the AC/FC ratio is particularly useful in newborn screening programs, as early detection of abnormalities can lead to timely interventions and management strategies that can significantly improve outcomes for affected individuals. By understanding and regularly assessing this marker, healthcare providers can better diagnose, treat, and manage metabolic disorders, ensuring that patients maintain optimal metabolic health.

Acylcarnitine is a crucial molecule in the body, playing a significant role in the metabolism of fatty acids. Essentially, it acts as a transporter that helps move fatty acids into the mitochondria, the energy powerhouses of our cells, where they can be broken down and used for energy production. The process begins when fatty acids bind to carnitine, forming acylcarnitine, which can then cross the mitochondrial membrane. Once inside the mitochondria, the fatty acids are released from carnitine and undergo a process called beta-oxidation, which ultimately generates ATP, the energy currency of cells. Measuring levels of acylcarnitines in the blood can provide valuable insights into metabolic health. Abnormal levels may indicate metabolic disorders such as fatty acid oxidation defects, which can lead to energy production issues and accumulation of toxic substances in the body. Therefore, understanding and monitoring acylcarnitine levels is important for diagnosing and managing various metabolic conditions.

a protein produced by fat cells

Adiponectin is a crucial marker often included in metabolic test panels to provide insights into an individual's metabolic health. This protein hormone, produced and secreted by fat cells, plays a significant role in regulating glucose levels and fatty acid breakdown in the body. High levels of adiponectin are associated with a lower risk of several metabolic disorders, including type 2 diabetes, obesity, and cardiovascular disease. Essentially, adiponectin enhances the body's sensitivity to insulin, making it an important indicator of metabolic syndrome and insulin resistance. When evaluating a metabolic test panel, health professionals look at adiponectin levels to assess a patient's risk for these conditions. Low adiponectin levels suggest a higher risk for developing metabolic diseases, prompting further investigation or intervention. Therefore, monitoring adiponectin levels can be a key factor in managing and preventing metabolic diseases, offering a window into the body's metabolic health and providing critical information for tailoring individual health strategies.

Albumin Excretion Rate (AER) What is Albumin Excretion Rate? The Albumin Excretion Rate (AER) measures the amount of albumin (a type of protein) excreted in the urine over a set period, usually in a 24-hour sample. It is a valuable marker for assessing kidney function, particularly in detecting early kidney damage or disease, such as diabetic nephropathy or hypertension-related kidney issues. Why is it Important? Albumin is normally present in very small amounts in urine, as the kidneys filter out waste but retain essential proteins. However, when the kidneys are damaged or stressed, they may leak albumin into the urine in higher amounts. Elevated levels of albumin in the urine can indicate kidney dysfunction, even before more noticeable symptoms arise. Monitoring AER is especially important in individuals with diabetes, hypertension, or other risk factors for kidney disease. Albuminuria Categories The American Diabetes Association (ADA) defines abnormalities in albumin excretion as follows: Normal to Mildly Increased: Less than 20 mcg/min Moderately Increased: 20-199 mcg/min Severely Increased: 200 mcg/min or greater Diagnostic Criteria The ADA recommends that at least two out of three specimens collected within a 3-6 month period should show abnormal results before a patient is categorized into one of the albuminuria categories. This helps confirm whether albumin excretion is consistently elevated and provides a more accurate assessment of kidney function. Reference Range A normal Albumin Excretion Rate is typically less than 20 mcg/min. Values above this threshold may suggest microalbuminuria (early kidney damage) or macroalbuminuria (more severe kidney damage). However, interpretation of results should always be done by a healthcare provider, who will consider the context of the individual's overall health and medical history. How is the Test Performed? AER is usually measured through a urine collection over 24 hours. The sample is then analyzed for the concentration of albumin. A spot urine test, which measures the albumin-to-creatinine ratio (ACR), can also be used as a quicker alternative to assess albumin excretion. What Can Affect Albumin Excretion Rate? Several factors can influence AER results, including: Exercise: Physical activity can temporarily increase albumin in the urine. Urinary Tract Infections (UTIs): Infections may lead to elevated albumin levels. Dehydration: Can affect the concentration of albumin in urine. Medications: Certain drugs, especially those used to treat high blood pressure or diabetes, may alter kidney function and affect AER. Acute illness: Conditions like fever or infection can transiently raise AER levels. Conclusion Albumin Excretion Rate is a critical biomarker for assessing kidney health. Consistently high levels of albumin in the urine can signal early kidney damage, making early detection crucial for preventing further progression of kidney disease. Regular monitoring of AER in individuals at risk can lead to more effective management of kidney health.

to detect elevated protein in urine

aid in assessing autoimmune thyroid disorders

a ketone body

C-Peptide, measured through the Liquid Chromatography-Tandem Mass Spectrometry (LC/MS/MS) method, represents a significant advancement in medical diagnostics, offering unparalleled accuracy in assessing pancreatic beta-cell function and insulin production. This test is crucial for differentiating type 1 and type 2 diabetes, as well as for identifying insulinoma, a rare pancreatic tumor. The C-Peptide test, especially when combined with LC/MS/MS technology, provides a highly sensitive and specific measure of C-Peptide levels, far surpassing traditional immunoassays in precision. This is particularly important in cases where distinguishing endogenous insulin production from exogenous insulin administration is critical. The test's precision makes it invaluable for evaluating residual beta-cell function in diabetes patients, guiding treatment decisions, and assessing the need for insulin therapy. Additionally, it's instrumental in the investigation of hypoglycemia, especially in post-gastric bypass patients or those suspected of insulin misuse. The role of C-Peptide testing via LC/MS/MS in personalized medicine is growing, as it aids in tailoring treatment plans based on individual beta-cell function, enhancing patient outcomes in diabetes management. With the increasing prevalence of diabetes globally, the demand for accurate diagnostic tools like C-Peptide, LC/MS/MS is surging, making it a focal point in endocrinological research and practice.

C-peptide is a substance made in the pancreas, along with insulin.

accurate way to find out how much insulin your body is making

help turn fat into energy

Serum carnitine analysis is useful in the diagnosis and monitoring of patients with carnitine deficiency (either primary or secondary).

Carnitine is a compound in the body that helps your body digest fats for energy. A carnitine deficiency is related to a number of different medical problems. A carnitine total and free plasma test is a blood test that measures the amount of carnitine in the blood. It examines that amount of usable, or free, carnitine and compares it with the total amount of carnitine. The analysis of carnitines is indicated in people who exhibit the following: - failure to thrive, - hypotonia, - chronic muscle weakness, - cardiomyopathy, - intermittent episodes of weakness and encephalopathy, - renal Fanconi's syndrome, - hypoglycemic episodes, - metabolic acidosis, - or hypoketotic dicarboxylic acidurias. ------------------ Reference Ranges: Carnitine is a quaternary, water-soluble ammonia compound biosynthesized from lysine and arginine. It serves as a mechanism for transport of long-chain fatty acids from the cytoplasm across the inner mitochondrial membrane and into the mitochondrial matrix, the site of b-oxidation of fatty acids for energy generation. The reference range of carnitine depends on the laboratory being used; Reference Range of Carnitine at a Single Laboratory Age Range Serum Free Carnitine (µmol/L) Serum Total Carnitine (µmol/L) Neonate 26-76 35-102 Child 41.4±10.4* 56.2±11.4* Adolescent female 39.3±8.1* 53.2±8.9* Adolescent male 39.6±9.3* 53.5±10.5* Adult female 19.3-53.9** 28.1-66.4** Adult male 38.8-69.5 44.2-79.3 *Mean ± standard deviation (SD) **95% confidence interval (CI) Quest Laboratories reports the reference range of total carnitine as follows: Men: 30-70 μmol/L Women: 25-58 μmol/L Male children (age ≤17 years): 32-62 μmol/L Female children (age ≤17 years): 28-59 μmol/L Quest Laboratories reports the reference range of free carnitine as follows: Men: 23-59 μmol/L Women: 19-48 μmol/L Male children (age ≤17 years): 25-54 μmol/L Female children (age ≤17 years): 19-51 μmol/L The University of California San Francisco Laboratory reports the normal values of free and total carnitine in adults as 18-69 μmol/L and 20-71 μmol/L, respectively. Chace et al (2003) examined free and total carnitine levels in newborns. The reference ranges depended both on technique used (radioenzyme vs tandem mass spectroscopy) and the sample type (whole blood vs serum). Variations in the ratio of free to total carnitine may also be important; typically, normal is reported as 0.1-0.4. References: Minkler PE, Stoll MS, Ingalls ST, Kerner J, Hoppel CL. Validated Method for the Quantification of Free and Total Carnitine, Butyrobetaine, and Acylcarnitines in Biological Samples. Anal Chem. 2015 Sep 1. 87 (17):8994-9001. [QxMD MEDLINE Link]. Belay B, Esteban-Cruciani N, Walsh CA, Kaskel FJ. The use of levo-carnitine in children with renal disease: a review and a call for future studies. Pediatr Nephrol. 2006 Mar. 21(3):308-17. [QxMD MEDLINE Link]. Quest Diagnostics. Available at http://www.questdiagnostics.com/testcenter/%20BUOrderInfo.action?tc=5800&labCode=AMD. Chace DH, Pons R, Chiriboga CA, et al. Neonatal blood carnitine concentrations: normative data by electrospray tandem mass spectometry. Pediatr Res. 2003 May. 53(5):823-9. [QxMD MEDLINE Link]. Stanley CA. Carnitine deficiency disorders in children. Ann N Y Acad Sci. 2004 Nov. 1033:42-51. [QxMD MEDLINE Link]. Reuter SE, Evans AM. Carnitine and acylcarnitines: pharmacokinetic, pharmacological and clinical aspects. Clin Pharmacokinet. 2012 Sep 1. 51(9):553-72. [QxMD MEDLINE Link]. Longo N, Amat di San Filippo C, Pasquali M. Disorders of carnitine transport and the carnitine cycle. Am J Med Genet C Semin Med Genet. 2006 May 15. 142C(2):77-85. [QxMD MEDLINE Link]. [Full Text]. Dahash BA, Sankararaman S. Carnitine Deficiency. StatPearls. 2022 Jan. [QxMD MEDLINE Link]. [Full Text]. Santra S, Hendriksz C. How to use acylcarnitine profiles to help diagnose inborn errors of metabolism. Arch Dis Child Educ Pract Ed. 2010 Oct. 95(5):151-6. [QxMD MEDLINE Link]. Scaglia F. Carnitine Deficiency. Medscape Drugs & Diseases. Updated 2019 Dec 13. [Full Text]. Magoulas PL, El-Hattab AW. Systemic primary carnitine deficiency: an overview of clinical manifestations, diagnosis, and management. Orphanet J Rare Dis. 2012 Sep 18. 7:68. [QxMD MEDLINE Link]. [Full Text]. Tein I. Metabolic myopathies. Swaiman KF, Ashwal S, Ferriero DM. Swaiman’s Pediatric Neurology Principles and Practice. 5th ed. Schor NF: Elsevier Sanders; 2012. 1627-40. Crefcoeur LL, Visser G, Ferdinandusse S, Wijburg FA, Langeveld M, Sjouke B. Clinical characteristics of primary carnitine deficiency: A structured review using a case-by-case approach. J Inherit Metab Dis. 2022 May. 45 (3):386-405. [QxMD MEDLINE Link]. [Full Text]. Berardo A, DiMauro S, Hirano M. A diagnostic algorithm for metabolic myopathies. Curr Neurol Neurosci Rep. 2010 Mar. 10(2):118-26. [QxMD MEDLINE Link]. [Full Text]. Bernardini I, Rizzo WB, Dalakas M, Bernar J, Gahl WA. Plasma and muscle free carnitine deficiency due to renal Fanconi syndrome. J Clin Invest. 1985 Apr. 75(4):1124-30. [QxMD MEDLINE Link]. [Full Text]. Gahl WA, Bernardini I, Dalakas M, et al. Oral carnitine therapy in children with cystinosis and renal Fanconi syndrome. J Clin Invest. 1988 Feb. 81(2):549-60. [QxMD MEDLINE Link]. [Full Text]. Determination of Free and Total Carnitine and Choline in Infant Formulas and Adult Nutritional Products by UHPLC-MS/MS: Single-Laboratory Validation, First Action 2014.04. J AOAC Int. 2015 Jun 24. [QxMD MEDLINE Link]. El-Hattab AW. Systemic Primary Carnitine Deficiency. 1993. [QxMD MEDLINE Link]. Rinaldo P, Cowan TM, Matern D. Acylcarnitine profile analysis. Genet Med. 2008 Feb. 10(2):151-6. [QxMD MEDLINE Link]. Dietzen DJ, Rinaldo P, Whitley RJ, et al. National academy of clinical biochemistry laboratory medicine practice guidelines: follow-up testing for metabolic disease identified by expanded newborn screening using tandem mass spectrometry; executive summary. Clin Chem. 2009 Sep. 55(9):1615-26. [QxMD MEDLINE Link]. Johns Hopkins University Clinical Lab. National Newborn Screening Status Report 2012. Stanley CA. Carnitine disorders. Adv Pediatr. 1995. 42:209-42. [QxMD MEDLINE Link]. Mamedov I, Zolkina I, Nikolaeva E, Glagovsky P, Sukhorukov V. Carnitine insufficiency in children with inborn errors of metabolism: prevalence and treatment efficacy. J Pediatr Endocrinol Metab. 2015 Jul 18. [QxMD MEDLINE Link]. Sgambat K, Moudgil A. Carnitine deficiency in children receiving continuous renal replacement therapy. Hemodial Int. 2015 Aug 11. [QxMD MEDLINE Link].

To measure the amount of ceruloplasmin in the blood; to help diagnose Wilson disease; sometimes to help identify conditions associated with copper deficiencies.

Choline is an essential nutrient involved in various physiological processes, including cell membrane structure, lipid metabolism, and neurotransmitter synthesis. When measured in a urine sample as choline (mg/g creatinine), this biomarker can provide valuable insights into an individual's choline status and overall metabolic health. The measurement of choline in urine is often normalized to creatinine levels to account for variations in urine concentration, making the value more reliable and comparable across different samples and individuals. Interpreting choline levels in urine requires considering dietary intake, as choline is obtained from foods such as eggs, meat, fish, and certain vegetables. Elevated choline levels in urine might indicate high dietary intake or supplementation, efficient absorption, and utilization, or potential metabolic disturbances where excess choline is excreted. Conversely, low levels could suggest inadequate dietary intake, poor absorption, or increased utilization within the body. Clinically, assessing urinary choline can aid in diagnosing nutritional deficiencies, monitoring dietary interventions, and understanding metabolic conditions. For accurate interpretation, it is essential to consider the individual's dietary habits, overall health status, and possibly other related biomarkers to get a comprehensive picture of their choline metabolism and nutritional state.

Coenzyme Q10, commonly referred to as CoQ10, plays an essential role in the body's energy production and is found in every cell, particularly in the mitochondria, which are often described as the powerhouses of the cells. It is involved in the production of adenosine triphosphate (ATP), which is a major energy currency of the cell. This makes CoQ10 crucial for the health and functioning of virtually all body systems and organs. In the context of cardiovascular health, CoQ10's importance cannot be overstated. It helps maintain the optimal functioning of heart cells, as well as supports the cardiovascular system's overall health. Low levels of CoQ10 have been associated with various health issues, including heart conditions and muscular disorders. By evaluating CoQ10 levels, healthcare providers can make more informed decisions about treatment strategies, which may include dietary supplements to support heart health and improve energy levels in individuals with deficient CoQ10 levels. Understanding your CoQ10 status can be a key step in taking charge of your cardiovascular health and overall well-being.

endproduct of creatine metabolism

Useful in the assessment of parathyroid function.

to assess your risk of developing type 2 diabetes

to assess your risk of developing type 2 diabetes

Potent androgen measured to assess excess androgens in females.

Dihydrotestosterone (DHT), the potent androgen made from testosterone.

Carnitine balance marker

Average blood glucose estimated from your A1c result.

Testosterone Measurement

a critical biomarker in diabetes research and management

Unbound testosterone level in serum or plasma

Free Testosterone in Women Free testosterone is the unbound, biologically active form of testosterone in the bloodstream. In women, it is typically measured in picograms per deciliter (pg/dL), with a reference range of 0.7 to 2.00 pg/dL. Significance Free testosterone plays a vital role in women's health by contributing to: Muscle strength Bone density Libido regulation Although present in much lower quantities than in men, free testosterone is essential for numerous physiological processes in women. Measurement and Interpretation Free testosterone levels can be assessed through several methods: Equilibrium dialysis – the gold standard for accuracy. Calculation – derived from total testosterone and SHBG using mass action equations. Free Androgen Index (FAI) – an alternative estimate. Direct radioimmunoassay (RIA) methods are less accurate and reliable for women, making equilibrium dialysis or calculated methods the preferred options. Clinical Relevance Abnormal free testosterone levels may indicate underlying health conditions: Elevated levels: Potentially linked to polycystic ovary syndrome (PCOS) or other androgen excess disorders. Low levels: Associated with androgen deficiency, which can affect overall well-being and sexual function. Accurate measurement of free testosterone is essential for the diagnosis and management of these conditions, ensuring effective treatment and better health outcomes.

related to hormonal balance and reproductive health

related to hormonal balance and reproductive health

Free testosterone and albumin-bound testosterone are also referred to as bioavailable testosterone. This is the testosterone that is easily used by your body.

not attached to any proteins

Free Testosterone, Direct (Female): A Key Marker for Women's Health Free testosterone, the unbound and biologically active form of the hormone, plays a vital role in women’s overall health. Although often associated with males, testosterone is essential for women as well, supporting critical functions such as muscle strength, energy, libido, and overall well-being. Importance of Free Testosterone Optimal levels of free testosterone in women are necessary for: Maintaining muscle mass and strength. Sustaining energy levels and physical stamina. Supporting a healthy libido and sexual function. Enhancing overall quality of life and well-being. Implications of Abnormal Levels Low Free Testosterone: Symptoms may include fatigue, reduced muscle strength, sleep disturbances, and diminished sex drive. High Free Testosterone: Often linked to conditions like polycystic ovary syndrome (PCOS). Symptoms can include infertility, irregular menstrual cycles, acne, and excessive hair growth (hirsutism). Why This Marker Matters Monitoring free testosterone levels is crucial for understanding hormonal balance and identifying potential underlying health conditions in women. It helps guide treatments to restore balance and improve overall health.

a compound that is formed when glucose combines with protein

A Key Biomarker in Energy Regulation and Metabolism

1-hour post-load glucose

2-hour post-load glucose

Enzyme

Glycated hemoglobin

a 2-3 week indicator of average blood glucose

Diabetes Risk

An estimate of your pancreas's insulin-producing beta-cell function.

Homeostatic Model Assessment for Insulin Resistance

index for assessing cellular sensitivity to insulin

Vitamin Deficiency Indicator

This test measures levels of Insulin-Like Growth Factor 1 (IGF-1) using liquid chromatography–mass spectrometry (LC/MS), one of the most accurate and specific testing methods available. IGF-1 plays a critical role in growth, metabolism, and cellular repair, and its levels reflect growth hormone (GH) activity in the body. Why Is IGF-1 Testing Important? IGF-1 testing is used to: Evaluate growth disorders in children and adults Diagnose and monitor acromegaly (excess growth hormone) Support diagnosis of growth hormone deficiency (GHD) Guide and monitor GH or IGF-1 replacement therapy Clinical Insights High IGF-1 levels may indicate acromegaly, a condition where the body produces too much growth hormone. IGF-1 levels are used both for diagnosis and to monitor treatment after surgery or with medications (e.g., somatostatin analogs, pegvisomant). Low IGF-1 levels may suggest growth hormone deficiency (GHD), especially in individuals with multiple pituitary hormone deficiencies or genetic conditions. IGF-1 is also useful in adjusting GH replacement therapy in both children and adults. Why LC/MS Testing Is Superior Most IGF-1 tests use immunoassays, which can give inaccurate results due to interference from IGF binding proteins (IGFBPs). LC/MS testing offers several advantages: Highly specific: Accurately measures intact IGF-1, minimizing interference from IGFBPs. Sensitive and reliable: Offers excellent precision with a coefficient of variation (CV) ≤5%. Detects rare IGF-1 variants, which may be missed by immunoassays. Standardized to WHO reference materials for consistent, comparable results. Note: LC/MS may yield lower IGF-1 levels than traditional immunoassays. This is due to technical differences, not necessarily a reflection of true biological variance. Always use the same method consistently for monitoring over time. Who Should Be Tested? This test is appropriate for individuals who may have: Short stature or delayed growth in children Gigantism or acromegaly symptoms (enlarged hands/feet, facial changes) Pituitary tumors or prior pituitary surgery Suspected adult growth hormone deficiency (especially with panhypopituitarism) Ongoing GH or IGF-1 therapy needing dosage adjustment How the Test Works Sample Type: Serum Method: High-resolution LC/MS with isotope-labeled internal standards Analytical Range: 10–2,000 ng/mL Reference Ranges: Adjusted by age and sex, based on data from over 2,000 individuals This method dissociates IGF-1 from its binding proteins and recovers nearly 100% of total IGF-1 for accurate measurement. Understanding Your IGF-1 Results Results are interpreted using Z-scores, which compare your IGF-1 level to the average for your age and sex. Z > +2.0: Suggests GH excess (e.g., acromegaly or over-treatment) Z between -2.0 and +2.0: Normal IGF-1 level Z < -2.0: Suggests GH deficiency or under-treatment A normal IGF-1 level does not fully exclude acromegaly or GHD. Follow-up testing (e.g., glucose suppression or GH stimulation) may be required in some cases. Key Considerations Stay consistent: Use the same assay method over time to monitor treatment. Don’t switch platforms without consulting your provider, as values may differ significantly between LC/MS and immunoassays. Rare IGF-1 variants, if present, are reported separately and may affect interpretation but are uncommon (<1% prevalence).

Measures baseline insulin concentration in fasting blood.

2-hour post-load insulin

The anti-insulin antibody test checks to see if your body has produced antibodies against insulin. Antibodies are proteins the body produces to protect itself when it detects anything "foreign," such as a virus or transplanted organ.

An elevated Insulin Resistance Score suggests your body may need more insulin to control blood sugar. Learn what it means, common causes, symptoms, and next steps to improve metabolic health.

a hormone that is similar in structure to insulin

measures the level of unbound, bioactive insulin

Highly specific insulin test

Fatty Acids, Free (Nonester)

Pregnenolone serum measured by liquid chromatography-mass spectrometry (LC/MS)

precursor of insulin and C-peptide

a protein produced by the liver that binds to sex hormones

Sex Hormone Carrier

This measurement is a calculation of T4 and T3 uptake.

also referred to as bioavailable testosterone

also referred to as bioavailable testosterone

also referred to as bioavailable testosterone

The marker "Testosterone, Free, Calculated (Female)" is an important parameter in assessing various health conditions and understanding the hormonal balance in females. Testosterone, although typically associated with males, is also a vital hormone in females, playing crucial roles in muscle strength, bone density, and sexual function. Unlike males, where testosterone is the primary sex hormone, females produce it in much smaller quantities. Its levels in the female body can be indicative of various health conditions, making its measurement and understanding critical in medical practice. Free testosterone refers to the fraction of testosterone that is not bound to proteins in the blood and is, therefore, available to tissues. The majority of testosterone in the bloodstream is bound to two proteins: sex hormone-binding globulin (SHBG) and albumin. The "free" portion of testosterone is biologically active, meaning it can interact with cells and potentially affect the body. Calculated free testosterone estimates the amount of testosterone that is not bound to SHBG or albumin, providing insights into the hormone's active levels. This calculation typically involves measuring total testosterone, SHBG, and sometimes albumin, using these values in a formula to estimate free testosterone levels. In females, the evaluation of testosterone levels, particularly free testosterone, is crucial for diagnosing and managing conditions such as polycystic ovary syndrome (PCOS), hirsutism, and other disorders that might involve androgen excess or deficiency. PCOS, for instance, is a common endocrine disorder in women of reproductive age, characterized by elevated levels of male hormones (androgens), which can lead to symptoms like irregular menstrual cycles, infertility, acne, and excess hair growth. By assessing free testosterone, healthcare providers can gain better insight into the hormonal imbalances at play and tailor treatment approaches accordingly. Moreover, low levels of testosterone in women can also be problematic, associated with reduced libido, fatigue, and decreased well-being. Thus, understanding and managing testosterone levels can be a delicate balance, requiring careful interpretation of test results within the context of the individual's symptoms and health status. It's also essential to consider that normal testosterone levels can vary widely among women, and what is normal for one individual may not be for another. As such, the clinical context, along with a comprehensive assessment of symptoms and other hormone levels, guides the interpretation of testosterone measurements in females. In summary, the marker "Testosterone, Free, Calculated (Female)" is a nuanced tool in the diagnostic and management arsenal of healthcare providers. It offers a window into the complex hormonal landscape of the female body, aiding in the diagnosis of androgen excess or deficiency conditions. Understanding and interpreting this marker require a deep knowledge of endocrinology and the physiological roles of hormones in the female body, emphasizing the importance of a personalized approach to healthcare.

Understanding Free Testosterone: A Critical Biomarker for Male Health What is Free Testosterone? Free testosterone is a key biomarker that measures the biologically active portion of testosterone circulating in the bloodstream. Unlike total testosterone, which includes both bound and unbound hormones, free testosterone represents the immediately available hormone that directly impacts physiological functions. Why Free Testosterone Matters Testosterone plays a crucial role in male health, influencing: Sexual function Muscle mass and strength Bone density Mood and cognitive performance Energy levels Metabolic processes Key Characteristics of Free Testosterone Composition Total testosterone: Includes bound and unbound hormones Free testosterone: Unbound, biologically active hormone Bound testosterone: Attached to proteins like SHBG and albumin Diagnostic Significance Free testosterone testing is particularly valuable for: Detecting hormonal imbalances Diagnosing low testosterone syndrome Monitoring hormone replacement therapy Evaluating reproductive health Identifying underlying metabolic conditions Reference Ranges Typical free testosterone ranges by age group: 20-29 years: 9.3–26.5 pg/mL 30-39 years: 8.7–25.1 pg/mL 40-49 years: 6.8–21.5 pg/mL 50+ years: 5.0–19.0 pg/mL Factors Affecting Free Testosterone Levels Primary Influences Aging Body composition Chronic health conditions Stress levels Medication interactions Common Symptoms of Low Free Testosterone Reduced libido Erectile dysfunction Fatigue Muscle mass loss Mood changes Cognitive difficulties Increased body fat Diagnostic Approach Free testosterone is calculated using a sophisticated formula that considers: Total testosterone levels Sex hormone-binding globulin (SHBG) Albumin concentrations Treatment and Management Strategies Lifestyle Interventions Regular strength training Balanced nutrition Stress management Weight control Medical Treatments Testosterone replacement therapy Hormonal medications Addressing underlying health conditions Who Should Consider Testing? Recommended for individuals experiencing: Persistent low energy Sexual health concerns Unexplained mood changes Metabolic health issues Age-related hormonal shifts Conclusion Free testosterone testing provides critical insights into male hormonal health. By understanding and monitoring this biomarker, individuals can take proactive steps toward optimizing their overall well-being.

Testosterone measures male and female sex hormone levels. Normal varies widely by sex and age. Low or high levels affect energy, libido, and health. HealthMatters.

Testosterone Measurement

All non-SHBG bound testosterone is considered bioavailable

a crucial hormone in men's health

an essential hormone

A male sex hormone produced in a woman’s ovaries in small amounts as well.

The testosterone-cortisol ratio (T/C ratio) is a crucial indicator in sports science, endocrinology, and physiology. This ratio helps assess the balance between anabolic (building up) and catabolic (breaking down) processes in the body, providing insights into your stress levels, recovery status, and overall hormonal health. What Are Testosterone and Cortisol? Testosterone: - Function: Testosterone is the primary male sex hormone. It plays a vital role in muscle growth, bone density, and the development of male characteristics. It also influences mood, energy levels, and libido. - Production: In men, testosterone is mainly produced in the testes. In women, it’s produced in smaller amounts in the ovaries and adrenal glands. Cortisol: - Function: Cortisol, often called the "stress hormone," is produced by the adrenal glands. It’s released in response to stress and low blood sugar. Cortisol helps regulate metabolism, control blood sugar levels, reduce inflammation, and aid memory formation. - Impact: While cortisol is essential, chronically high levels can lead to muscle breakdown, increased fat deposition, impaired immune function, and mental health issues like anxiety and depression. Why the Testosterone-Cortisol Ratio Matters The T/C ratio is a key indicator of your body’s anabolic (building) and catabolic (breaking down) balance: - Anabolic Processes: Driven by testosterone, these processes involve tissue growth, muscle repair, and overall physical development. - Catabolic Processes: Driven by cortisol, these involve tissue breakdown to provide energy during stress or fasting. A high T/C ratio indicates a favorable anabolic environment, suggesting good recovery and adaptation to training. A low T/C ratio may signal overtraining, high stress, or inadequate recovery, indicating a catabolic state. Factors That Affect the T/C Ratio Training Load: Intense or prolonged exercise can temporarily lower the T/C ratio due to increased cortisol levels and/or decreased testosterone levels. Nutrition: Proper nutrition, especially adequate protein intake, supports higher testosterone levels and helps maintain a favorable T/C ratio. Sleep: Poor sleep can elevate cortisol levels and lower testosterone levels, negatively affecting the T/C ratio. Stress: Chronic stress increases cortisol production, lowering the T/C ratio. Age and Sex: Testosterone levels naturally decline with age, and men typically have higher testosterone levels than women, affecting the baseline T/C ratio. Health Conditions: Conditions like adrenal fatigue, hypogonadism, and metabolic disorders can significantly alter the T/C ratio. How to Measure the T/C Ratio The T/C ratio is typically measured through blood or saliva tests. These tests assess the concentrations of testosterone and cortisol in the body. The ratio provides a comprehensive picture of your body’s anabolic and catabolic balance. Practical Uses of the T/C Ratio Athlete Monitoring: Coaches and sports scientists use the T/C ratio to monitor athletes' training status, ensuring they are not overtraining and are recovering adequately. Health Assessment: The ratio can assess overall hormonal health and stress levels, guiding interventions for better health and well-being. Performance Optimization: By maintaining a favorable T/C ratio, you can optimize physical performance, muscle growth, and recovery processes.

Thyroglobulin is the protein precursor of thyroid hormone and is made by normal well differentiated benign thyroid cells or thyroid cancer cells.

Understanding Thyroglobulin Testing by RIA (Radioimmunoassay) Thyroglobulin (Tg) is a protein produced by the thyroid gland and plays a key role in the production of thyroid hormones. Measuring thyroglobulin levels can be an important diagnostic tool, particularly for individuals with thyroid cancer or other thyroid-related conditions. One of the most reliable methods for testing thyroglobulin levels is through Radioimmunoassay (RIA). What is Thyroglobulin? Thyroglobulin is stored in the thyroid gland and is used as a building block for thyroid hormones, such as thyroxine (T4) and triiodothyronine (T3). Normally, small amounts of thyroglobulin are released into the bloodstream. However, when thyroid cells are damaged or overactive, as in conditions like thyroid cancer, thyroiditis, or hyperthyroidism, thyroglobulin levels may rise. Why is Thyroglobulin Testing Important? Thyroglobulin testing by RIA is commonly used for the following purposes: Monitoring Thyroid Cancer: For patients who have had thyroid cancer, especially papillary or follicular thyroid cancer, thyroglobulin levels can be monitored after treatment to check for recurrence. After thyroidectomy (surgical removal of the thyroid gland), thyroglobulin levels should be very low or undetectable. Rising levels could indicate the return of thyroid tissue or cancer cells. Assessing Thyroid Function: Elevated thyroglobulin levels may signal thyroid inflammation (thyroiditis) or hyperactivity (hyperthyroidism). It helps in understanding whether the thyroid gland is functioning normally. Evaluating Treatment: For patients undergoing radioactive iodine therapy, thyroglobulin testing helps assess how effective the treatment is in destroying thyroid tissue or cancer. How is Thyroglobulin Measured by RIA? Radioimmunoassay (RIA) is a highly sensitive technique that measures thyroglobulin in the blood. It involves using radioactively labeled antibodies that bind specifically to thyroglobulin. This method is known for its accuracy, making it ideal for monitoring thyroid conditions over time. What Do the Results Mean? Normal Range: Thyroglobulin levels can vary depending on the laboratory, but generally, a typical range might be 0 to 40 ng/mL in individuals with a thyroid gland. After complete removal of the thyroid gland (thyroidectomy), levels should be near zero or undetectable. Elevated Thyroglobulin: High thyroglobulin levels may indicate the presence of thyroid tissue or thyroid cancer cells. Other possible causes include thyroid inflammation or overactivity. Low or Undetectable Levels: In patients who have undergone thyroidectomy, low or undetectable thyroglobulin levels are a positive sign, indicating that no significant thyroid tissue remains. Out-of-Range Results: What to Do? If your thyroglobulin levels are outside the normal range, your healthcare provider will help interpret what this means for you. For example: If elevated: Your doctor may conduct further tests, including imaging or additional blood work, to investigate possible thyroid cancer recurrence or other thyroid-related conditions. If normal or undetectable: This is generally reassuring, especially for patients in remission from thyroid cancer. Your doctor may still recommend periodic monitoring.

used to diagnose Graves' disease

TMA (Trimethylamine) and TMAO (trimethylamine N-oxide) are key biomarkers in understanding the connection between diet, gut microbiota and heart health. TMA is a small molecule produced by the gut microbiota when we digest certain dietary components like choline, lecithin and L-carnitine which are found in red meat, eggs and dairy. Once TMA is formed in the gut it’s absorbed into the blood and transported to the liver where it’s converted to TMAO by the enzyme flavin-containing monooxygenase 3 (FMO3). High levels of TMAO have been linked to increased risk of cardiovascular disease (CVD) like atherosclerosis, heart attacks and strokes. TMAO is thought to contribute to atherosclerosis by promoting cholesterol deposition in the artery walls and inhibiting reverse cholesterol transport. TMAO can also influence platelet function and increase the risk of thrombosis. Research has shown TMA and TMAO can be used as biomarkers of dietary intake and microbiota activity, linking specific dietary patterns to CVD risk. So measuring TMA and TMAO in the blood can be a useful tool in clinical settings to predict and manage CVD risk. Reducing TMAO production through dietary changes such as reducing TMA precursors or altering gut microbiota through probiotics or other interventions has been suggested as a way to mitigate CVD risk associated with high TMAO levels.

Trimethylamine N-oxide (TMAO) is a small organic compound that has garnered significant attention in recent years due to its association with cardiovascular health and disease. TMAO is derived from the oxidation of trimethylamine (TMA), which is produced by gut microbiota during the digestion of certain dietary nutrients, particularly choline, lecithin, and L-carnitine. These nutrients are predominantly found in red meat, eggs, dairy products, and some fish. Once TMA is absorbed into the bloodstream, it travels to the liver, where it is converted into TMAO by the enzyme flavin-containing monooxygenase 3 (FMO3). The presence of TMAO in the bloodstream has been linked to various adverse health outcomes, most notably cardiovascular diseases (CVD). Elevated TMAO levels are associated with an increased risk of atherosclerosis, which is the buildup of fatty deposits in the arteries. This process can lead to the hardening and narrowing of arteries, impeding blood flow, and potentially resulting in heart attacks, strokes, and other cardiovascular events. One of the mechanisms by which TMAO promotes atherosclerosis is by enhancing the deposition of cholesterol in the arterial walls and impairing reverse cholesterol transport, a critical process in which cholesterol is removed from tissues and transported to the liver for excretion. Beyond its impact on cholesterol metabolism, TMAO also influences platelet function, increasing the risk of thrombosis. This pro-thrombotic effect of TMAO can contribute to the formation of blood clots, which are dangerous as they can obstruct blood vessels and lead to acute cardiovascular events. Given these effects, TMAO is not only a marker of dietary intake and gut microbiota activity but also a potential therapeutic target for reducing cardiovascular risk. The regulation of TMAO levels involves a multifaceted approach, including dietary modifications, gut microbiota modulation, and potentially pharmacological interventions. Reducing the intake of foods high in TMA precursors is a primary strategy. Additionally, promoting a healthy gut microbiota through probiotics and prebiotics can help mitigate the production of TMA. Research is also exploring the role of specific enzymes involved in TMA to TMAO conversion, which could lead to new treatments aimed at lowering TMAO levels. Despite the established links between TMAO and cardiovascular health, the field is still evolving, with ongoing research aimed at better understanding the exact mechanisms and potential interventions. The complexity of TMAO's role in human health underscores the importance of a comprehensive approach that considers dietary habits, gut microbiota, genetic factors, and overall metabolic health. As science advances, the insights gained about TMAO will continue to shape strategies for preventing and managing cardiovascular diseases, highlighting the intricate connections between diet, gut health, and systemic disease processes.

a metabolite derived from gut bacteria

used to measure the overall insulin levels in the bloodstream

Thyroid Hormone

often present in the serum of patients with Graves’ disease

a normal metabolite that accumulates in trace amounts in erythrocytes during heme synthesis

This test is mainly used to assist in the diagnosis of type 1 diabetes mellitus. For this purpose, it can be used alone or in combination with other antibody tests such as the glutamic acid decarboxylase-65 (GAD-65), insulinoma antigen-2 (IA-2), and insulin antibody tests. The Zinc Transporter 8 (ZnT8) antibody is a marker of significant interest in the field of endocrinology, particularly in relation to diabetes. ZnT8 is a protein that plays a critical role in the insulin secretion process within the pancreas. It is involved in the transport of zinc ions into insulin-containing secretory vesicles, a step that is essential for the proper storage and processing of insulin. The presence of antibodies against ZnT8 is indicative of an autoimmune response, where the body's immune system mistakenly targets and attacks the cells that produce insulin, leading to the destruction of these cells. This autoimmune response is a hallmark of Type 1 diabetes, making the ZnT8 antibody a valuable biomarker for early detection and diagnosis of the disease. Identifying the presence of ZnT8 antibodies can help in distinguishing Type 1 diabetes from other types of diabetes, which is crucial for determining the most effective treatment strategy. Moreover, the detection of ZnT8 antibodies can also be used for identifying individuals at risk of developing Type 1 diabetes, allowing for early intervention and potentially delaying or preventing the onset of the disease.