A survey of renal function in outpatients with rheumatoid arthritis.

The acute renal side-effects of nonsteroidal anti-inflammatory drugs are well documented. These include interstitial nephritis, hyperkalaemia, renal tubular acidosis, fluid retention, hypertension and nephrotic syndrome. The long-term effects are less well known. We have carried out a cross-sectional survey of an unselected out-patient population with definite or classical rheumatoid arthritis to determine the prevalence of renal problems in this group. Thirty-four patients (20%) were shown to have an abnormality as defined by our criteria but in the majority this was transient or had been previously recognised. Thirteen patients (8%) had a persistent unexplained abnormality but only 1 had merited renal biopsy using established criteria (Patient 1). We conclude that the long-term use of NSAID's is associated with relatively few renal side-effects.