creatininebased

Creatininebased describes approaches, measurements, or calculations that rely on creatinine as a key biomarker to assess kidney function or to normalize urinary excretion of other substances. Creatinine, a waste product of muscle metabolism, is filtered by the kidneys and is commonly measured in blood and urine for clinical assessment.

The most widespread use of creatininebased methods is estimating glomerular filtration rate (eGFR). Equations such as the MDRD (Modification of Diet in Renal Disease) and the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) use serum creatinine, along with factors like age, sex, and sometimes race, to approximate GFR. Creatinine-based estimates help stage chronic kidney disease, guide dosing of medications, and monitor kidney function over time. Another common application is the urine albumin-to-creatinine ratio (ACR), which normalizes urinary albumin concentration to creatinine to screen for or quantify albuminuria, enabling comparisons across samples with varying urine concentration.

Methods and interpretation depend on standardized assays. Modern practice emphasizes IDMS-traceable creatinine measurements to improve comparability across laboratories. Limitations of creatininebased approaches include sensitivity to muscle mass, age, sex, diet, and certain medications, which can bias results especially in the elderly, very muscular individuals, or those with malnutrition. In acute kidney disease, creatinine-based estimates may lag behind real-time changes in filtration. Because of these limitations, alternative markers (for example, cystatin C) or combined equations may be used in some situations.

See also: eGFR, MDRD, CKD-EPI, creatinine clearance, albuminuria, albumin-to-creatinine ratio.