What do the four kidney function tests check?

Generally, the four main tests for kidney function primarily examine the levels of serum creatinine, blood urea nitrogen, uric acid, and cystatin C in the blood, although specific testing parameters may vary between hospitals. Detailed explanations are as follows:

1. Serum Creatinine

Serum creatinine is a metabolic product of muscle in the human body and is mainly filtered and excreted from the body through the glomeruli. The level of serum creatinine reflects the glomerular filtration function and is a commonly used indicator for assessing kidney function in clinical practice.

2. Blood Urea Nitrogen

Blood urea nitrogen is a major end product of protein metabolism in the body, synthesized from urea produced by the liver and urea ammonia from alcohol metabolism. It is transported via the blood to the kidneys, where it is excreted from the body through urine. The level of blood urea nitrogen reflects the kidneys' ability to excrete amino acids and other nitrogen-containing metabolic products.

3. Uric Acid

Uric acid is the end product of purine metabolism. Under normal circumstances, the kidneys excrete uric acid from the blood. The level of uric acid can reflect whether the excretory function of the kidneys is normal.

4. Cystatin C

Cystatin C is a protein produced by renal tubular cells and is a type of cysteine protease inhibitor. It can freely pass through the glomerular basement membrane and serves as an indicator for detecting early kidney function damage. The serum concentration of cystatin C is not affected by factors such as gender, age, or muscle mass, making it a more sensitive marker for detecting early kidney function impairment.

The four main kidney function tests are important methods for evaluating kidney function, helping to detect kidney diseases promptly, guide treatment, and prevent kidney-related conditions. If you have any concerns or symptoms, please seek medical attention promptly and follow the advice of your physician.