Follow-up of GFR estimated from plasma creatinine after cimetidine administration in patients with diabetes mellitus type 2
Kemperman, F.A.; Silberbusch, J.; Slaats, E.H.; Prins, A.M.; Krediet, R.T.; Arisz, L.
Clinical Nephrology 54(4): 255-260
2000
ISSN/ISBN: 0301-0430 PMID: 11076100 Document Number: 516406
Background: The glomerular filtration rate (GFR) can be estimated from plasma creatinine according to the formula of Cockcroft and Gault (CG). When tubular secretion of creatinine is inhibited by cimetidine the mean difference between the Cockcroft-Gault clearance (CGCim) and GFR approximates zero, but there is still some interindividual difference, especially in type-2-diabetic patients. We studied during longitudinal follow-up, whether the discrepancies between CGCim and GFR per patient are consistent in time in type-2-diabetic patients. Patients and methods: In 1996 and 1998 (interval 20-26 months) GFR was measured in 21 patients as the urinary clearance of continuously infused 125I-iothalamate. Plasma creatinine was analyzed with an enzymatic assay before and after oral cimetidine 800 mg t.i.d. during 24 hours. GFR estimations were calculated with the Cockcroft-Gault formula before (CG) and after cimetidine (CGCim) and expressed as means +- SEM. Results: GFR deteriorated from 89.7 +- 5.7 to 81.3 +- 5.8 ml/min/1.73 m2 and CGCim from 85.3 +- 5.7 to 81.1 +- 6.6 ml/min/1.73 m2, whereas CG decreased from 102.4 +- 6.8 to 98.4 +- 7.0 ml/min/1.73 m2. Changes in GFR and changes in CGCim were correlated (r = 0.72, p < 0.001) and were not significantly different from each other. The discrepancy between CGCim and GFR per patient in 1996 also correlated with the discrepancy between CGCim and GFR in 1998 (r = 0.85, p < 0.001). Conclusions: In individual patients the discrepancies between the CGCim and GFR are consistent in time and the change in GFR is reflected by the change in CGCim. This small variability means that CGCim, based on an enzymatic plasma creatinine assay, would be suitable for follow-up of GFR in type-2-diabetic patients, independent of albuminuria.