Nephropathy in patients with drug addiction. Evolution of pathological and clinical features.

The course of the nephropathy in patients with drug addiction has been studied in six subjects. The nephrotic syndrome with the presenting feature in all, with two progressing to terminal renal failure in less than a year. Serial percutaneous renal biopsies revealed the basic lesion to be a mild non-specific increase in PAS-positive material in the mesangial areas. This was more marked in the two patients with renal failure who, in addition, had segmental PAS-positive material in the glomerular capillary loops, focal tubular dilatation and atrophy, interstitial edema and mononuclear cell infiltration. Immunofluorescent staining revealed lumpy granular staining. IgG, present at the onset of the nephrotic syndrome, subsided as the first two patients developed renal failure, while beta1C and IgM, negative at the onset, became positive. Electron microscopy revealed focal basement membrane thickening and deposition of homogenous, finely granular electron-dense material predominantly in the mesangial areas. Our findings indicate that renal damage secondary to immune-complex deposits develops in the addict. The presence of interstitial swelling, mononuclear infiltration and tubular dilatation signals rapid deterioration of renal function and a grave prognosis, while their absence indicates a more prolonged indolent course.