What is Kidney Function Test?
Kidney function tests are the tests performed to evaluate kidney functioning. These tests reveal the functioning and abnormalities if any. Some of the commonly conducted laboratory tests are
- BUN test – Blood, urea, and nitrogen
- Creatinine – blood
- Creatinine clearance
- Creatinine urine
Blood urea nitrogen (BUN): The BUN test measures the nitrogen content in blood urea. Urea is a waste product released from the degradation of protein, which is filtered in the blood and excreted in urine by kidneys. The normal values of nitrogen in blood urea range from 7mg/dL to 20mg/dL. Elevated levels suggest impaired kidney function such as acute or chronic kidney disease, decreased blood flow to kidneys as in congestive heart failure and shock. Decreased concentration of BUN is not common and may occur in cases of malnutrition and severe kidney disease.
Blood Creatinine: This test measures the amount of creatinine in the blood which signifies the filtering capability of kidneys. Creatinine is a byproduct of creatine produced when muscles are put to use. Creatinine is filtered from the blood and excreted in urine by the kidneys. The normal value of creatinine is 0.8 – 1.4mg/dL Females have low creatinine than males because of the muscle mass. If the level of creatinine is more than the normal value it indicates kidney conditions such as glomerulonephritis, pyelonephritis, acute tubular necrosis, kidney stones, prostate disease, and complications of diabetes. Creatinine levels may be decreased slightly in pregnancy.
Creatinine clearance: This test determines the kidney functioning and suggests kidney dysfunction or decreased blood flow to kidneys as in congestive heart failure. Creatinine is the waste product released when the muscle is put to work. It is also done to estimate the glomerular filtration rate (GFR). The normal value in males is 97 to 137 mL/min and a female is 88 to 128mL/min. If the GFR is high then it may indicate chances of kidney failure.