[Primary microvascular lesions of the kidney or pre-hypertensive nephroangiosclerosis. 25 cases]

Isolated non inflammatory lesions of renal microarteries (eventually with mild thickening of tubular basement membranes, but with negative immunofluorescent glomerular studies) were observed in 25 patients (22 males) in whom renal biopsy have been performed for proteinuria (P). Selection criteria were: pathological lesions by definition; absence of hypertension (HT) in clinical and at the time of biopsy; minimum follow up of 4 years after the first statement of the proteinuria (4 to 29 years; mean 14 years). Three groups have been isolated: 1. 3 patients have had an acute glomerulonephritis followed by disappearance of proteinuria. It reappears 1 to 5 years later. HT was discovered 2, 8 and 11 years after the proteinuria. Renal failure occurred 1 and 3 years after HT. 2. 14 patients had hereditary or acquired vascular risk factors (obesity, smoking, ethylism). In 7, HT occurred 3 to 15 years after P. In 2, renal failure occurred 4 to 8 years later. 3. 8 patients had no vascular risk factor; in 3 of them Ht developed 7, 13 and 20 years after the first statement. A positive immunofluorescence with IgM or C3 on renal arterioles had been found in only 3 of the 10 patients who in group 2 and 3 became hypertensive. A proteinuria may precede the occurrence of HT without being induced by glomerulonephritis. Group 2 and 3 suggest that these renal lesions of arterial sclerosis precede and may be a factor of HT. Indeed, this entity may be considered as a prehypertensive condition.