Serial measurements of cystatin C are more accurate than creatinine-based methods in detecting declining renal function in type 1 diabetes.
OBJECTIVE
Cystatin C-and creatinine-based methods were compared with (99m)-technetium-diethylene-triamine-penta-acetic acid ((99m)Tc-DTPA) plasma clearance (isotopic glomerular filtration rate [iGFR]) for detecting declining renal function.


METHODS
Glomerular filtration rate (GFR) was monitored over a mean of 10.1 years in 85 subjects with type 1 diabetes (with an average of 5.6 measurements per individual). Baseline mean +/- SD iGFR of the cohort was 106.1 +/- 2.6 ml/min per 1.73 m(2). The rates of decline in GFR (DeltaGFR) were derived using linear regression.


RESULTS
In 19 of 85 subjects with declining renal function (i.e., DeltaiGFR >3.3 ml/min per 1.73 m(2) per year), DeltaGFR (ml/min per 1.73 m(2) per year) was 6.5 by iGFR, 4.2 by 10(4)/creatinine, 3.6 by Cockcroft-Gault formula, 3.4 by the Modification of Diet in Renal Disease (MDRD)-6 equation, and 3.5 by the MDRD-4 variable equation (P < 0.01 vs. iGFR). In comparison, DeltaGFR was 6.1 using the formula Cys-GFR = (86.7/cystatin C concentration) - 4.2 (not significant).


CONCLUSIONS
Cystatin C was more accurate in detecting decline in renal function than creatinine-based methods in this population of subjects with type 1 diabetes and a normal mean baseline GFR.
Premaratne
Erosha
E
Endocrine Centre, Austin Health, University of Melbourne, Melbourne, Australia. erosha@aanet.com.au
MacIsaac
Richard J
RJ
Finch
Sue
S
Panagiotopoulos
Sianna
S
Ekinci
Elif
E
Jerums
George
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D044466:Asian People; D001315:Australia; D003404:Creatinine / Q000097:blood; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D003928:Diabetic Nephropathies / Q000097:blood* / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D044465:White People
C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D003404:Creatinine