Cystatin C is a low molecular weight cysteine proteinase inhibitor that is produced by all nucleated cells and found in body fluids, including serum. Since it is formed at a constant rate and freely filtered by the kidneys, its serum concentration is inversely correlated with the glomerular filtration rate (GFR); that is, high values indicate low GFRs while lower values indicate higher GFRs, similar to creatinine. The renal handling of cystatin C differs from creatinine. While both are freely filtered by glomeruli, once it is filtered, cystatin C, unlike creatinine, is reabsorbed and metabolized by proximal renal tubules. Thus, under normal conditions, cystatin C does not enter the final excreted urine to any significant degree. The serum concentration of cystatin C remains unchanged with infections, inflammatory or neoplastic states, and is not affected by body mass, diet, or drugs. Thus, cystatin C may be a more reliable marker of renal function (GFR) than creatinine.
No special preparation is needed for Cystatin C. Inform your doctor if you are on any medications or have any underlying medical conditions or allergies before undergoing Cystatin C. Your doctor depending on your condition will give specific instructions.
|MALE||All age groups||0.6 - 1.42mg/ml|
|FEMALE||All age groups||0.62 - 1.07mg/L|