ANTIGLOMERULAR BASEMENT-MEMBRANE (GBM) ANTIBODY-MEDIATED DISEASE WITHNORMAL RENAL-FUNCTION

Background. This study compared the clinical and laboratory characteri stics of patients with antiglomerular basement membrane (GBM) disease and normal renal function, with those of patients with anti-GBM diseas e where there was renal impairment. Methods. The medical records of th e 14 patients who had presented with anti-GEM disease to our hospital in the past 20 years were reviewed. Results. Five (36%) had a normal s erum creatinine or creatinine clearance at presentation. Other feature s were haemoptysis (2/5, 40%), macroscopic haematuria (2/5, 40%) or sy stemic symptoms (1/5, 20%). All five (100%) had some degree of haematu ria, four (80%) had proteinuria of at least 1 g/day, and none was hype rtensive. Anaemia, a raised WCC, or elevated ESR (>35 mm/h) occurred l ess often than in patients with impaired renal function (P<0.05). Two of the five (40%) with normal renal function had circulating anti-GEM antibodies, which were present at low or moderate levels; but seven of the nine with renal impairment (77%) had circulating antibodies, with high levels in five. Renal biopsies from patients with normal renal f unction were normal (1/5, 20%), showed mesangial proliferation (4/5, 8 0%) or had more than 20% glomeruli sclerosed (1/5, 20%). Complement de position was present in 2/4 biopsies (50%). The kidneys from patients with renal impairment had crescents in more than 50% glomeruli (9/9, 1 00%), and four had more than 20% glomeruli sclerosed (44%). All four k idneys from patients with renal impairment that were examined had comp lement deposits (100%). Treatment was identical in both groups; patien ts with normal renal function were followed for a median of 48 months, and those with renal impairment for 180 months. There were no further episodes of haemoptysis, haematuria, or other symptoms of relapse in either group. All five patients with normal renal function are alive, and the serum creatinine is less than 0.2 mmol/l in all (100%), but ha ematuria persists in one (20%), and proteinuria >1 g/day in two (40%). Eight of the nine (89%) patients with impaired renal function survive , but all are currently being dialysed or have had a renal transplant. Conclusion. Patients with anti-GEM disease with normal renal function are not uncommon, and often have a good prognosis. There is less rena l damage, possibly because of lower levels of circulating anti-GBM ant ibodies and less glomerular complement deposition.