Cystatin C

Cystatin C is a low molecular weight polypeptide, which belong to the natural inhibitors of cycteine proteinases termed (Cystatins).

Recently Cystatin C has been introduced in the clinical Laboratory Diagnostic field as an important marker for nephron loss or damage and proved to be more sensitive than serum creatinine due to dependence of the latter on muscle mass and the severity of liver cell dysfunction.

Although both creatinine and Cystatin C are endogenously formed, Cystatin C is more reliable in assessment of glomeruler function due to its low molecular weight which allows free filtration through glomerali, in addition to its production at a constant rate.

In the blind phase of Creatnine in which kidney clearance test link inulin inulin clearance move severe damage of patient glomerali, serum creatinine didn't show clear abnormality, while Cystatin C show parallel abnormality with clearance test.

There fore measurement of Cystatin C is very useful in:

Assessment of post Natal renal function in bilateral Uropathy.
Monitoring glomeruler function in pediatric population.
Early detection of Nephropathy in:

• Diabetic patients.
• Hepato-renal failure.
• In datients who show low kidney clearance test with no clear abnormality in serum creatinine.