ENLARGEMENT OF THE JUXTAGLOMERULAR APPARATUS IN INSULIN-DEPENDENT DIABETES-MELLITUS PATIENTS WITH MICROALBUMINURIA

Kidney biopsies from 15 insulin-dependent diabetes mellitus (IDDM) pat ients with microalbuminuria were investigated to obtain quantitative d ata on the juxtaglomerular apparatus. The IDDM patients were young and normotensive with a mean duration of microalbuminuria of 2 years. Eig ht healthy kidney donors served as controls. Measurements taken by lig ht microscopy, using 1-mu m serial sections of epon blocks, included v olumes of the juxtaglomerular apparatus and of glomeruli, areas of the macula densa and luminal area of the juxtaglomerular (afferent and ef ferent) arterioles at the level of the glomerular vascular pole. The v olume of the juxtaglomerular apparatus was significantly larger in the IDDM group than in controls [6.08 (2.96-18.8) 10(4) mu m(3) vs 3.48 ( 1.84-5.21) 10(4) mu m(3), P=0.003, median and (range)], as was the vol ume of the juxtaglomerular apparatus relative to glomerular volume [1. 89 (1.28-4.21)% vs 1.48 (1.13-1.71)%, P=0.004]. The area of the macula densa was also larger in the IDDM patients (1370 mu m(2) vs 937 mu m( 2), P=0.03). Luminal areas of the afferent and efferent arterioles and the ratio between them did not differ significantly between the two g roups. In conclusion, the juxtaglomerular apparatus is enlarged more t han would be expected from the glomerular hypertrophy in IDDM patients with microalbuminuria.