CLINICOPATHOLOGICAL STUDY OF IGA NEPHROPATHY IN PATIENTS WITH CONGENITALLY REDUCED NEPHRON MASS

In experimental animal models, a reduction in the number of functionin g nephrons is considered to play a role in the progression of glomerul ar injury, In human renal diseases, however, whether a superimposed re duction in the number of nephrons causes the exacerbation of preexiste nt glomerulopathy has not been elucidated. We herein report the result s of a clinicopathological study of five patients with IgA nephropathy (IgAN) which occurred in a reduced nephron mass status (four cases of congenital solitary kidney and one case of bilateral hypoplastic kidn eys), Four of the five patients had chronic renal failure (CRF) and ex hibited a relatively rapid course to CRF as primary IgAN. Renal biopsy revealed that all four of the patients with CRF had glomerular hypert rophy and focal segmental glomerular sclerosis. In addition, two of th em had a focal active lesion. In one pa tient with bilateral hypoplast ic kidneys renal biopsies were performed twice in eight years. During this period her creatinine clearance deteriorated from 60.0 ml/min to 20.7 ml/min. Her first renal biopsy showed mild mesangial proliferatio n without sclerotic lesions, glomerular hypertrophy and mesangial IgA deposition, while all of them were prominent in the second renal biops y. These observations suggest that IgAN superimposed on a nephron loss status may be frequently associated with a progressive course of dise ase, and careful follow-up and early treatment should be considered in such a condition.