Kidney function tests check how well the kidneys filter and
transport waste materials from the blood into the urine. Kidney
function tests are usually ordered when a healthcare provider
suspects a disease that may be affecting the kidneys, when a
patient has high blood pressure, or an abnormal urinalysis.
These tests are also used to monitor someone who already has
kidney disease. There are four major tests. Each test is
described more fully in separate articles in this encyclopedia.
They are: BUN in a blood samplecreatinine in a blood
samplecreatinine in the urine (in a single sample or in a
"24-hour urine" collectiona "clearance" test Creatinine and BUN
are blood tests that measure metabolic breakdown products from
protein in general and from breakdown protein in muscle). It is
the role of the kidney to get rid of these waste products in the
urine. When the kidney does not work properly, these products
are not put into the urine and the levels become elevated in the
blood. Urine creatinine measures the amou