Kidney Function Tests


Kidney function test is a combined term for a several specified tests and methods that can be administered to access how properly the kidneys are working. A doctor who prescribes kidney function tests and uses the results to analyze the functioning of the kidneys is called a nephrologist.

The kidneys, the body's inbuilt filtration system, perform several important functions, including discarding metabolic waste materials from the bloodstream, regulating the body's water equilibrium, and maintaining the pH of the body's fluids. Almost one and a half quarts of blood every minute are circulated via kidneys, where waste chemicals are filtered out and discarded from the body (with excess water) in the form of urine. Kidney function tests enable to identify if the kidneys are working perfectly.


The doctor should analyze a complete history before conducting kidney function tests to analyze the patient's food and drug intake. A wide spectrum of prescription and over-the-counter drugs can affect blood and kidney function test outcomes, as can a few food and beverages.


Many situations can influence the kidneys to function properly. Some conditions can result in a rapid (acute) alleviation in kidney function; others may lead to a simultaneous (chronic) decline in performance. Both can lead to collecting harmful waste material in the blood. Several clinical laboratory tests that identify the quantity of substances basically monitored by the kidneys can determine the cause and seriousness of kidney dysfunction. Urine and blood samples are recommended for such tests.

The nephrologist facilitates these tests in various ways. Once a diagnosis is conducted that kidney disorder is present, the nephrologist may advise a specific treatment. Although there is no particular drug therapy that will curb the development of kidney disease, the doctor will prescribe treatment to simmer down the disease to an extent.

Laboratory Tests

There are several urine tests that can be conducted to realize kidney function. A simple routine urinalysis is often the initial test conducted if kidney disorder is suspected. A small, randomly collected urine sample is analyzed physically for its color, odor, texture, and concentration, chemically, for elements like glucose, protein, and pH and microscopically for the presence of red blood cells, white blood cells, epithelial cells, bacteria, casts, and crystals. If results pinpoint a susceptibility of disease or impaired kidney working, one or more of the following tests is generally prescribed to pinpoint the cause and the stage of decline in kidney function.

Urine Tests

Creatinine Clearance Test

This test analyzes how properly the kidneys drains out a substance called creatinine from the blood.

Urea Clearance Test

Urea is a waste product, created by protein metabolism and collected in the urine. This test evaluates the quantity of urea in the bloodstream.

Urine Osmolality Test

Urine osmolality is to measure the number of dissolved component present in urine.

Urine Protein Test

Normal kidneys strain the entire proteins from the blood vessels and reabsorb them, enabling no protein, or only mild quantity of protein, to go into the urine.

Blood Tests

Low clearance values for creatinine signals a reducing ability of the kidneys to filter from the blood the waste products and discharge them in the urine. With the decreasing levels, the blood level ofcreatinine, uric acid and urea enhances. As it can be influenced by other components, an enhanced BUN, alone is advisable, but not for kidney dysfunction. An abnormally increased plasmacreatinine is a particular signal of kidney disorder compared to BUN. 

The incapability of the kidneys to condense the urine in response to limited fluid intake, or to water down urine in response to enhanced fluid intake during osmolality testing, may signaleliminating kidney performance. Because the kidneys generally excrete almost no protein in the urine, its prolonged presence in enhanced amount, basically indicates some type of kidney disorder.