British Journal of Rheumatology 1991;30:115-118 RENAL TUBULAR DYSFUNCTION IN RHEUMATIC DISEASES

Evidence of renal tubular dysfunction as defined by abnormal urinary levels of a, and (32 microglobulin with or without microalbuminuria was found in 47 (16.5%) of 285 patients with a variety of rheumatic diseases, compared with a preva-lence of <1 % in 500 healthy adults. Previous work from this unit has shown a prevalence of tubular dysfunction of 24 % in patients with severe rheumatic disease admitted to hospital, probably associated with severe rheumatoid arthritis. Although our study confirms a high prevalence of renal tubular dysfunction, we have shown that it is related to age and intercurrent illness, particularly urinary tract infection, rather than to rheumatic disease or drug therapy, although it is possible drug therapy could add to a compound insult on an ageing or damaged kidney. KEY WORDS: Renal tubular dysfunction, a, microglobulin, p"2 microglobulin, Rheumatoid arthritis, Gold, Penicillamine, Non-steroidal anti-inflammatory drugs. Low molecular weight proteins P2 microglobulin (11.5 kDa) and a, microglobulin (31 kDa) are readily filtered by the glomerulus and re-absorbed and catabolized by proximal tubular cells [1]. Both are useful indicators of renal tubular dysfunction [1,2] although P2 micro-globulin has the disadvantage of instability in urine o