Contribution of the MDRD equation and of cystatin C for renal function estimates in cancer patients.
BACKGROUND
Serum creatinine (SCr) and Cockcroft-Gault creatinine clearance (CG CrCL) are used to estimate glomerular filtration rate (GFR). Other markers have been proposed including serum cystatin C (cysC) and the Modification of Diet in Renal Disease (MDRD) study equation.


METHODS
We have compared the diagnostic performances of SCr, cysC, CG CrCL, and the MDRD equation in 144 cancer patients. For reference we used either the measured or the predicted carboplatin clearance, which is around the GFR + 25 mL/min.


RESULTS
CysC was more sensitive than SCr (70.1% vs 13.4%) but was not very specific (61% for a cut-off = 0.95 mL). CysC values were higher in 40 cancer patients vs 40 healthy controls with a similar and normal mean CG CrCL (1.08 vs 0.71 mg/L; p < 0.001). CG and the MDRD equations gave similar values for Pearson's coefficient, ROC-plot AUC, and precision, except for patients with poor general status, where the MDRD equation was better (MAPE: 12.4% vs 19.6%, p < 0.001; R: 0.908 vs 0.813).


CONCLUSIONS
In cancer patients, cysC is a more sensitive indicator of the glomerular filtration rate than SCr, but its diagnostic performance is lower than for CG CrCL. There may be no advantage in replacing the CG equation by the MDRD equation except for patients with severe malnutrition and/or inflammation.
Séronie-Vivien
Sophie
S
Department of Clinical Biology, Institute Claudius Regaud, Toulouse, France. seronie@icr.fnclcc.fr
Toullec
Stéphanie
S
Malard
Laurence
L
Thomas
Fabienne
F
Durrand
Valérie
V
Chatelut
Etienne
E
D000328:Adult; D000368:Aged; D016190:Carboplatin / Q000493:pharmacokinetics; D003404:Creatinine / Q000097:blood; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D004032:Diet; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D007677:Kidney Function Tests / Q000379:methods*; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009369:Neoplasms / Q000503:physiopathology*
C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D003404:Creatinine; D016190:Carboplatin