Blood Test Kidney Function High. Creatinine passes into the bloodstream and is usually passed out in urine. The blood urea nitrogen bun test checks for other waste products in the blood such as urea nitrogen.
As kidney disease progresses the level of creatinine in the blood rises. A more precise measure of the kidney function can be estimated by calculating how much creatinine is cleared from the body by the kidneys. These tests used together give an indication of overall kidney function but the best way to know if your kidneys are working properly is to measure the glomerular filtration rate gfr.
Creatinine levels in the blood can vary depending on age race and body size.
High bun levels can point to kidney dysfunction but since blood urea nitrogen is affected by protein intake and liver function too the test is typically completed together with a blood creatinine a more exact indicator of kidney function. It is for this reason that standard blood tests routinely check the amount of creatinine in the blood. Gfr is a measure of kidney function and is performed through a blood test. Creatinine is usually a more accurate marker of kidney function than urea.