How to Calculate Kidney Function

Kidneys are responsible for clearing the body from byproducts of metabolism, and they help the body with absorption of water. As the body metabolized things like drugs and food, the waste products are sent through the blood to the glomeruli, which comprise the filtration system of the kidneys. Harmful waste is excreted through the urine and valuable compounds like sodium and water are absorbed and recycled to the body. The function of the kidney can be calculated to evaluate the filtration efficiency and detect kidney failure.

Instructions

• 1

  Weigh yourself and convert to kilograms. There are a few factors in calculating kidney function. Two factors that are easy to collect are age and weight. Weight should be in kilograms, so use the following conversion formula to calculate pounds to kilograms.

  Pounds/2.2 = kilograms

• 2

  Collect lab results from blood or urine tests. When going for a checkup, you can ask for lab tests for kidney function. Blood is taken and sent to a lab where results will be sent back to the doctor. You can request these numbers since it is a part of your medical history.

• 3

  Find the multiplication factor depending on gender and ethnicity. Ethnicity plays a part in determining kidney function. Blacks have generally higher muscle mass than whites and men have more muscle mass than women. For blacks, the multiplication factor is 1.18, and females use a multiplication factor of .85. For all others, the factor is 1.2.

• 4

  Plug in values for the formula. Below is the equation for kidney function.

  Creatinine clearance = 1.2 x ((140 - age in years) x weight in kg)/lab creatinine values

  For a 33 year old, white male weighing 200 pounds, and with creatinine serum lab results of 110mmols/liter:

  Creatinine clearance = 1.2 x ((140-33) x 90.9kg)/110

• 5

  Calculate and evaluate creatinine clearance levels. From the equation, the clearance level is:

  1.2 x ((140-33) x 90.9kg)/110 = 106.1051Ccr (creatinine clearance rate)

  A value over 75 is normal kidney function, but any value under 75 signals reduced kidney function and should be checked by a doctor.