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Glomerular structure in nonproteinuric IDDM patients with various levels of albuminuria
Although microalbuminuria is known to foretell the later development of overt proteinuria in patients with insulin-dependent diabetes mellitus (IDDM), different investigators have reported different levels of albuminuria as being predictive. However, whether different levels of albuminuria reflect differences in glomerular structure is not well known. In this study, we divided a cohort of 66 nonproteinuric long-standing (duration 20 ± 7 years) IDDM patients, who had both renal functional and structural studies performed, into four groups according to their urinary albumin excretion rate (AER). The several different levels of microalbuminuria previously reported to be predictive served to demarcate these groups: group I, AER ≤22 mg/24 h (upper limit for normal in our laboratory) (33 patients); group II, AER 23- 45 mg/24 h (11 patients); group III, AER 46-100 mg/24 h (13 patients); and group IV, AER 101-220 mg/24 h (9 patients). Creatinine clearance was similarity in groups I, II, and III but was lower in group IV. Systemic hypertension was present in five patients in group I, one in group II, seven in group III, and five in group IV. Mean values for glomerular basement membrane (GBM) width and volume fraction of the mesangium [Vv(mes/glom)] were greater in all groups than in a group of 52 age-matched normal kidney donors (P 45 but 100) does not discriminate groups with different glomerular lesions. Therefore, albuminuria >45 mg/24 h indicates more advanced diabetic glomerulopathy and is frequently associated with other functional abnormalities such as reduced glomerular filtration rats and increasing blood pressure. These results are consistent with the majority of studies that have found the higher ranges of microalbuminuria to predict progression to overt nephropathy with greater specificity
Renal structure and function in insulin-dependent diabetes mellitus and type I membranoproliferative glomerulonephritis in humans.
An overview of renal pathology in insulin-dependent diabetes mellitus in relationship to altered glomerular hemodynamics.
Renal interstitial expansion in insulin-dependent diabetes mellitus.
Renal interstitial expansion in insulin-dependent diabetes mellitus. Eighty-four patients with insulin-dependent diabetes mellitus had studies of renal function and quantitative renal morphometry including mesangial volume fraction (Vvmes/glom), index of arteriolar hyalinosis, percentage of globally sclerosed glomeruli (%GS), and interstitial volume fraction for total renal cortex (Vvint/T). There was significant correlation among these four parameters, and all four structural parameters correlated with glomerular filtration rate and the log of urinary albumin excretion. Stepwise multiple regression analysis showed that Vvmes/glom and Vvint/T were additive, suggesting that they are partially independent. Arteriolar hyalinosis and %GS did not improve the correlations further. We hypothesize that Vvmes/glom, Vvint/T, arteriolar hyalinosis, and %GS represent multiple but probably interrelated pathologic mechanisms leading to the functional disturbances of diabetic nephropathy. Longitudinal studies of patients with diabetes and studies of patients with diseases producing interstitial expansion in the absence of glomerular disease may help clarify the independent role of interstitial expansion in the kidney disease of diabetes mellitus
Effects of pancreas transplantation on glomerular structure in insulin-dependent diabetic patients with their own kidneys.
Is diabetic nephropathy inherited? Studies of glomerular structure in type 1 diabetic sibling pairs.
Sequential renal biopsies in insulin-dependent diabetic patients: structural factors associated with clinical progression.
Sequential renal biopsies in insulin-dependent diabetic patients: Structural factors associated with clinical progression. Quantitative structural studies in native kidneys of IDDM patients have almost all been cross sectional, and little is known regarding the dynamics of progression of structural lesions in relation to clinical progression. It has been suggested that interstitial may be more important than glomerular changes in determining functional outcome. This study evaluated renal structure in sequential biopsies from IDDM patients with established renal lesions to determine whether glomerular, arteriolar and interstitial changes progress together and in concordance with measures of renal function. Eleven long-term IDDM patients [age 29 ± 10 years, duration 17 ± 7 years (mean ± SD)] had renal function studies and kidney biopsies performed at two occasions 5.6 ± 1.6 years apart. HbA1 as well as creatinine clearance (CCr) did not change over this time; albumin excretion rate (AER) increased from 12 (6 to 280) to 19 (5 to 2462) [median (range)] mg/24hr (P < 0.03). AER increased in the three patients with abnormal albuminuria at first observation, and two normoalbuminuric patients became microalbuminuric. Blood pressure (BP) did not change; however, the number of patients on antihypertensive therapy increased from 1 to 5. All structural parameters were abnormal at first evaluation. Mesangial fractional volume [Vv(mes/glom)] and mean glomerular volume increased and the surface density of the peripheral glomerular basement membrane (GBM) decreased, while GBM width did not change over the five years of the study. Also, arteriolar hyalinosis lesions progressed, while the fractional volume of cortical interstitium [Vv(interstitium/cortex)] and the percent of globally sclerosed glomeruli did not change. The only structural change that correlated with the increasing AER was the change in Vv(mes/glom). Changes in structural parameters, AER or CCr did not significantly correlate with baseline BP or change in BP over the five years. Although based on a small number of patients, this study suggests that at the stage of disease where renal lesions are established and where some IDDM patients are in transition to microalbuminuria or early clinical nephropathy, continuing mesangial expansion is the central variable. Interstitial changes were not occurring over this time. Progressive interstitial expansion at the later stages of diabetic nephropathy may thus be consequent to advanced diabetic glomerular injury
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