Creatinine is a metabolic waste product that is released into the bloodstream during muscle contractions. Under normal kidney function, creatinine is efficiently filtered out of the blood by the kidneys. Elevated creatinine levels can serve as an indicator of potential kidney dysfunction or disease. In adults, when estimated glomerular filtration rate (GFR) levels drop to approximately 10.0 ml/min, dialysis may be recommended. Your physician can provide insights into your GFR level, which is determined through a laboratory test measuring creatinine.
Doctors employ two additional tests to assess creatinine levels: creatinine clearance (Ccr or CrCl) and BUN/creatinine. Creatinine clearance involves a combination of blood and urine tests to gauge the rate at which creatinine is cleared from the body, reflecting kidney filtration efficiency. This test is often ordered if there are indications of kidney problems or if dialysis initiation is imminent. BUN/creatinine, on the other hand, is a ratio between blood urea nitrogen (BUN), a byproduct of protein metabolism in the blood, and creatinine. This ratio helps assess kidney function, identifying whether it is compromised due to kidney damage or disease, or if other factors unrelated to the kidneys are at play. The serum creatinine and BUN/creatinine tests are typically part of routine blood work. When an individual has kidney disease, their physician regularly conducts creatinine tests to monitor disease progression and determine the appropriate course of kidney disease treatment.
