Kidney Health

Your kidneys help maintain blood pressure, keep the blood's acid-base level within a healthy range, and filter the blood so nutrients are absorbed and waste is passed out of the body as urine. Your kidney function reflects how well your kidneys are filtering your blood. Abnormal kidney function could result in the accumulation of waste products in the body, which can cause fatigue, headaches, nausea, and more.

Blood urea nitrogen (BUN)

Optimal range: 6 - 24 mg/dL

BUN, or blood urea nitrogen, is used predominantly to measure kidney function. BUN reflects the ratio between the production and clearance of urea in the body. Urea is formed almost entirely by the liver from both protein metabolism and protein digestion. The amount of urea excreted as BUN varies with the amount of dietary protein intake.

Increased BUN levels are a sign of kidney dysfunction. An increased BUN level may be due to increased production of urea by the liver or decreased excretion by the kidney. Increased BUN levels are also associated with dehydration and hypochlorhydria.

Decreased BUN levels are associated with malabsorption and a diet low in protein.


BUN/Creatinine Ratio

Optimal range: 10 - 24 :1 ratio

What is the BUN/Creatinine Ratio?

The Blood urea nitrogen (BUN): Creatinine Ratio [BUN/Creatinine Ratio] is a renal (related to kidneys) function indicator, commonly used to diagnose acute or chronic renal (kidney) disease or damage.

Blood Urea Nitrogen (BUN) and creatinine are both waste products of normal metabolism in the human body. 

BUN represents the amount of nitrogen produced from the metabolism of proteins. 

Creatinine is a normal waste product of muscle. 

Once a person performs both a BUN and Creatinine test, doctors can use the combined results to find the BUN-to-creatinine ratio. The BUN and creatinine tests alone are excellent methods of testing liver and kidney health, but together, doctors get a much better understanding of your kidney health and can provide a more accurate diagnosis to kidney-related issues.

Most clinicians agree that creatinine is a more specific indicator of glomerular function than BUN. However, the BUN to creatinine ratio may be used as an indirect estimate of renal function. 

Note: If results for BUN and Creatinine are both within the normal reference range, the BUN/Creatinine ratio will not be reported (not applicable).


Creatinine, Serum

Optimal range: 0.57 - 1 mg/dL

Creatinine is formed by the breakdown of creatine, a key molecule in muscular metabolism. Our kidneys are responsible for removing creatinine from the blood and expelling it in urine. Therefore, blood creatinine levels are a good indicator of how well the kidneys are working. A disorder of the kidney and/or urinary tract will reduce the excretion of creatinine and thus raise blood serum levels. Creatinine is traditionally used with BUN to assess for impaired renal function.

- Increased creatinine levels are associated with kidney dysfunction, kidney disease and a possible dysfunction in the prostate.

- Decreased creatinine levels are associated with muscle atrophy due to creatinine’s connection to muscle metabolism.


Cystatin C

Optimal range: 0.52 - 1.27 mg/L

Cystatin C is a relatively small protein that is produced throughout the body by all cells that contain a nucleus and is found in a variety of body fluids, including the blood. It is produced, filtered from the blood by the kidneys, and broken down at a constant rate.


eGFR - Estimated Glomerular Filtration Rate (African Am)

Optimal range: 60 - 150 mL/min per 1.73 m2

eGFR stands for estimated glomerular filtration rate. Your eGFR score is a reflection of your blood test for creatinine, a waste product formed in muscular metabolism. It estimates how well your kidneys are working.


eGFR - Estimated Glomerular Filtration Rate (Non-African Am)

Optimal range: 60 - 150 mL/min per 1.73 m2

Alternative Names: GFR; Estimated GFR; eGFR

What is GFR?

GFR is a blood test that measures how much blood your kidneys filter each minute, which is known as your glomerular filtration rate (GFR). You have two kidneys. Their main job is to filter wastes and extra water out of your blood to make urine. eGFR is a measure of how well your kidneys are working. Measuring serum creatinine along with an estimated glomerular filtration rate (eGFR) is recommended as the first step in GFR evaluation by current clinical practice guidelines. Your eGFR is an estimated number based on a blood test and your age, sex, body type and race. eGFR is considered a mostly reliable test for doctors to know how well your kidneys are working. However, the eGFR may not be accurate if you are younger than 18, pregnant, very overweight or very muscular. In addition, other tests such as  an ultrasound or a kidney biopsy may be ordered to find a cause of your kidney disease.


Urea nitrogen/Creatinine

Optimal range: 9 - 23 Ratio

Uric Acid

Optimal range: 3.8 - 8.4 mg/dL

Uric acid is a natural byproduct formed during the breakdown of our body’s cells and the food that we eat. Excess uric acid can be caused by either an overproduction of uric acid or inefficient removal of it from the blood. The most common affliction associated with excess uric acid is gout, a painful form of arthritis.

May indicate oxidative stress and elevated levels are associated with cardiovascular disease and diabetes. May be elevated due to gout, kidney dysfunction, excess alcohol intake, starvation, extreme calorie restriction, liver dysfunction, hemolytic anemia, excess fructose consumption, fungal infection, ketogenic diet, supplemental niacin, high protein diet, prolonged fasting, supplemental vitamin B3, excess acidity. May be decreased due to nutrient deficiencies (molybdenum, zinc, iron), oxidative stress, low purine intake (vegetarian or vegan), excess alkalinity.