Metabolic Health

The free androgen index is a measure of the biologically active testosterone in the blood. It is a ratio of the total testosterone to the level of sex hormone-binding globulin (SHBG).

Testosterone is the primary male sex hormone in humans. A healthcare professional may order a free testosterone blood test if you’re experiencing sexual problems or a secondary condition, like hyperthyroidism, is suspected.  

Thyroxine is a hormone produced by the thyroid gland. The term “free thyroxine” means the measured thyroxine that is not bound to proteins in the blood.

Glucose is a simple sugar used as a primary energy source in our bodies. Blood glucose tests are most frequently ordered for the diagnoses and monitoring of diabetes. 

Glutamic acid decarboxylase is an enzyme found in brain and pancreas that converts glutamic acid (glutamate) into GABA, an inhibitory neurotransmitter. The glutamic acid decarboxylase test is a test that looks for antibodies directed against the glutamic acid decarboxylase enzyme.

Hemoglobin A1c (HbA1c) is the percentage of hemoglobin molecules with attached glucose molecules. HbA1c is an accurate means to estimate the average blood glucose over the preceding 3 months. 

Homocysteine is an amino acid that requires vitamin B12 and folate to be used by our bodies. As such, homocysteine blood tests are often ordered to identify vitamin B12 / folate deficiency.  Rarely, an abnormally high level of homocysteine indicates a rare genetic disorder called homocystinuria.

IGF-1 measurements are adjusted for age because levels tend to decrease as you get older.

Results of IGF-1 are given in nanograms per milliliter (ng/mL). Normal ranges by age are:

- 182 to 780 ng/mL for ages 16 to 24

- 114 to 492 ng/mL for ages 25 to 39

- 90 to 360 ng/mL for ages 40 to 54

- 71 to 290 ng/mL for people 55 and older

Reverse T3 is a biologically inactive thyroid hormone; however, it does block the conversion of thyroxine (T4) to triiodothyronine (T3). Higher levels of reverse T3 can decrease the effect of thyroid hormone.

Sex hormone-binding globulin is a protein that binds primarily to testosterone, making it biologically unusable by our bodies. For this reason, an abnormal level of SHBG indicates that too much or too little testosterone is present in the tissues. In men, this can cause sexual issues like erectile dysfunction or infertility. In women, it can cause irregular menstruation or excess facial hair growth. A healthcare professional may order a SHBG test when total testosterone levels do not fit with one or more of the above-mentioned symptoms.

Triiodothyronine or T3 is the most biologically active thyroid hormone in humans. The term “free T3” means the amount of T3 that is not bound to proteins in the blood.

Thyroxine or T4 is a hormone produced by the thyroid gland. The term “free T4” means measured T4 that is not bound to proteins in the blood.

Thyroxine (T4) is a hormone produced by the thyroid gland. It is sometimes called total thyroxine because it includes both free T4 and T4 bound to proteins.

Testosterone is the primary male sex hormone in humans. Testosterone blood tests can assess testosterone that is bound to a protein, testosterone that is free in the blood, or both. A healthcare professional may order any of these tests if you’re experiencing sexual or hormonal problems.

Testosterone is a male sex hormone or androgen. It is generally low in women and children, but it can be elevated in certain diseases. A certain level of testosterone is important for development and maturation in both genders.

Thyroglobulin antibodies are antibodies that recognize and bind to thyroglobulin, interfering with its function. Thyroglobulin is critical for thyroid hormone production, so thyroglobulin antibodies usually indicate thyroid disease.

Thyroid peroxidase (TPO) is an enzyme that is critical for to thyroid hormone synthesis in the thyroid gland. Thyroid peroxidase (TPO) antibodies bind to and block the action of TPO, resulting in decreases in thyroid hormone levels. 

TSH stands for thyroid stimulating hormone, though it is sometimes called thyrotropin or thyrotropic hormone. TSH stimulates the thyroid gland to produce thyroid hormone, which is is critical for the proper function of virtually every cell in the body.

Triiodothyronine or T3 is the most biologically active thyroid hormone in humans. It is called total T3 because it includes both free T3 and T3 bound to proteins.

Triiodothyronine (T3) is the most biologically active thyroid hormone in humans. It is sometimes called total triiodothyronine because it includes both free triiodothyronine and triiodothyronine bound to proteins.