Role of GFR estimation in assessment of the status of nephropathy in type 2 diabetes mellitus.

ABSTRACT

OBJECTIVES: Study the status of glomerular filtration rate (GFR) estimation vis-a-vis other noninvasive modes of assessment of renal involvement in Type2 Diabetes Mellitus (T2DM) and assess the temporal profile of the prevalence of nephropathy with a cross sectional cohort. METHODS: A total of 100 patients of T2DM were selected after screening and segregated into 3 groups according to duration of T2DM. Duration of < 5 years constituted group A and had 31 patients, group B duration was between 5-15 years and had 40 patients, rest belonged to group C with duration > 15 years. The parameters studied and compared were (1) various grades of albuminuria--normal, micro and macro by 24 hrs. urinary albumin excretion rates (UAER- gm/24 hr), (2) sonologically detected renal size(normal, small, large) and morphology (loss or presence of corticomedullary differentiation, (3) serum creatinine level (</> 1.4 mg/dl) and (4) different levels (high, normal, low, very low) of GFR (ml/min) by DTPA renal scan. RESULT ANALYSIS: There was high prevalence of nephropathy in all durations. Microalbuminuria had a high prevalence in patients of shorter duration (group A-74.2%). Albuminuria increased with duration but plateued off with longer duration (> 15 yrs) (UAER - 0.0842 +/- 0.083 vs. 0.906 +/- 0.84 vs. 1.346 +/- 1.28). Sonographic loss of corticomedullary differentiation and azotemia were late feature only and none had a contracted kidney. Only the parameter of GFR showed a graded and rather linear decrement with duration (132.57 +/- 19.3 vs. 76.33 +/- 20.8 vs. 40.08 +/- 17.1). Hyperfiltration had a high prevalence in patients of early detection (61.3%) and was the earliest change noted before change in any other parameter. GFR shows wide variation in various grades of albuminuria, especially microalbuminuria, and azotemia. A value in the normal range was uncommon (8%). CONCLUSION: GFR estimation is probably the most rational noninvasive mode of assessing the renal status in patients of T2DM, irrespective of the status of the other noninvasive methods as they express significant variation in inception and progression.