Definition Kidney function tests check how well the kidneys filter and transport waste materials from the blood into the urine.
Who is a candidate for the test? Kidney function tests are usually ordered when a doctor suspects a disease that may be affecting the kidneys. These tests are also used to monitor someone who already has kidney disease.
How is the test performed? There are four major tests. Each test is described more fully in separate articles in this encyclopedia. They are:
Creatinine and Urea are blood tests that measure metabolic breakdown products in the body. It is the role of the kidneys to get these waste products into the urine. When the kidneys do not work properly, these products are not put into the urine and the levels become elevated in the blood.
Urine creatinine measures the amount of creatinine that is excreted into the urine.
Creatinine clearance is a fairly precise way to estimate the exact amount of function of the kidneys compared to normal. Any of these tests may be ordered to help measure kidney function. Which one is used often depends on the disease that is suspected.
What is involved in preparation for the test? Specific instructions are provided by the doctor.
What do the test results mean? Please refer to the results section in each separate article for the individual tests listed above.
Author: David T. Moran, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 6/06/2005 Contributors Potential conflict of interest information for reviewers available on request
