In a prospective study of idiopathic glomerulonephritis we determined
the natural history of 49 adult patients (12 primary IgA nephropathy,
13 thin GBM nephropathy, 20 normal renal tissue and 4 miscellaneous ne
phropathies) who presented with idiopathic non-protein-uric non-azotem
ic hematuria of at least six months duration, in the absence of hypert
ension and with a negative urological work-up. The median follow-up wa
s 11 years with a range of 8 to 14 years. At the end of the follow-up,
renal function had remained stable in all subsets except for those wi
th miscellaneous disease. Hematuria was still present in all patients
with thin GBM nephropathy, in all but two patients with IgA nephropath
y who went into immunopathological remission, in three out of four mis
cellaneous nephropathies, and in seven out of 20 patients with normal
renal tissue. Of the latter patients five had a history suggestive of
urolithiasis at follow-up, which was in the absence of hypercalciuria
and hyperuricosuria. Seven thin GBM patients, five IgA nephropathy pat
ients and three miscellaneous nephropathies developed hypertension; th
e incidence of hypertension in each subset was significantly higher th
an in patients with normal renal tissue. This study shows that in youn
g adults with idiopathic chronic non-proteinuric hematuria of four yea
rs duration, renal biopsy will give a definite diagnosis in 86% of the
patients, and that those patients with so-called minor glomerular dis
eases are at high risk for hypertension. Those patients with normal re
nal tissue have a high incidence of urolithiasis and should have an ur
ological follow-up.