SUBCLINICAL RENAL TOXICITY IN RHEUMATIC PATIENTS RECEIVING LONG-TERM TREATMENT WITH NONSTEROIDAL ANTIINFLAMMATORY DRUGS

Objective. To study the possible renal toxicity of longterm treatment with nonsteroidal antiinflammatory drugs (NSAID), in a population of p atients with rheumatic diseases. Methods. Comparative study of 104 pat ients treated for more than 2 years with NSAID and 123 healthy control s, nonusers of these drugs. After fasting during 12 h the following te sts were performed in both groups: urinalysis, creatinine clearance, o smolar clearance, negative free water clearance, and urinary excretion of sodium. Results. In the patient group the urinary pH was higher th an in the controls (5.9 +/- 0.7 versus 5.2 +/- 0.6 p <0.05) and in add ition, they had an impaired renal concentration capacity, as it is sho wn by a significant decreased urinary density (1018.6 +/- 4.7 vs 1026. 3 +/- 5.4 in the controls p <0.05), a decreased urinary osmolality (50 2.1 +/- 150.7 vs 661.6 +/- 157.6 mOsm/ml p <0.001), a lower osmolar cl earance (1.26 +/- 0.25 ml/min vs 1.83 +/- 0.4 ml/min p <0.001) and an increased free water clearance(-0.21 +/- 0.40 ml/min vs -0.98 +/- 0.41 ml/min, p <0.001). This renal impairment was related to the cumulativ e intake of NSAID. Conclusion. The longterm treatment with NSAID is ab le to produce a subclinical renal dysfunction, consistent with the ear ly stages of analgesic nephropathy.