Changes of Glomerular Basement Membrane(GBM) Thickness in Rheumatoid Arthritis Patients with Urinary Abnormalities

Yum, Ju Hyup; Hong, Eun Kyung; Park, Moon Hyang

Abstract

We reviewed forty renal biopsies from 39 patients of rheumatoid disease with urinary abnormalities. Pathologic findings were as follows : 11 cases with normal or minor glomerular abnormalities(MGA), 10 with membranous glomerulonephropathy, 6 with IgA nephropathy, 4 with mesangial proliferative glomerulonephritis, 3 with renal amyloidosis, 2 with interstitial nephritis, 2 with minimal change disease(MCD), 1 with focal segmental glomerulosclerosis, and 1 with microscopic polyangiitis. Among 11 cases with MGA both in light and immunofluorescent microscopy, 8 cases were analyzed morphometrically with electron micrographs to determine the variation of thickness of the glomerular basement membrane. The mean GBM thickness was 334.5+/-76nm and was not statistically significantly different to that of control(391+/-39 nm, p>0.05). Of these, one case showed diffuse attenuation of GBM(175.1+/-27.6nm) to meet the criteria of thin basement membrane disease. Also, another case showed normal finding. Mean GBM thickness of the remaining 6 cases, excluding these 2 cases, was 344.7+/-31.3nm. The proportion of attenuated foci (less than 300nm) was increased ranging from 30.3% to 40.5% of total measurements of GBM(control 11.4 %, p<0.02). Another cases with distinct renal diseases also showed segmental attenuation of GBM (22-30.3%). In conclusion, the renal manifestations were variable in patients with rheumatoid disease and segmental thinning of GBMs was noted in most cases, which may evoke idiopathic hematuria during the course of RA. The renal morphologic lesion in RA patients with isolated proteinuria and those with hematuria can not be accurately predicted on the basis of clinical symptoms and signs. Prospective long-term studies are necessary to determine the nature and consequences of the condition.