Issue 134 Item 10 Plasma Cystatin More Accurate than Plasma Creatinine and 24-h

Plasma cystatin C may be a useful marker of early renal insufficiency in patients with Type 1 diabetes. That according to researchers from the UK report in the November issue of Diabetes Care.

In their report, Dr. G. D. Tan of the Oxford Centre for Diabetes, Endocrinology, and Metabolism note that "plasma creatinine is insensitive for a glomerular filtration rate (GFR) >50 ml/min and creatinine clearance is unwieldy and subject to collection inaccuracies."

The investigators assessed the reproducibility and reliability of plasma cystatin C as a measure of GFR ranging from normal to moderately impaired in 29 type 1 diabetics and 11 nondiabetics.

They compared plasma cystatin C with 24-hour creatinine clearance, serum creatinine level, and GFR estimated from plasma creatinine using the Cockcroft-Gault formula, as well as the gold standard, iohexol clearance.

In this "thorough" comparison study, cystatin C outperformed the other routine clinical measures of renal function, according to the team. Plasma cystatin C was "more accurate than plasma creatinine and the Cockcroft-Gault estimation of creatinine clearance and more reliable than 24-h creatinine clearance."

The authors encourage larger prospective studies to confirm the role of cystatin C as a clinical measure of GFR in type 1 diabetes. Diabetes Care 2002;25:2004-2009.