Salicylates and renal function in rheumatoid arthritis

Area of Science:

• Nephrology
• Rheumatology
• Pharmacology

Background:

• Salicylates are commonly used for rheumatoid arthritis (RA).
• Potential renal side effects of salicylate therapy require investigation, particularly concerning medullary function.

Purpose of the Study:

• To investigate the effects of salicylate treatment on kidney function, specifically medullary function.
• To assess urinary concentrating power and markers of renal tubular damage in patients receiving salicylates.

Main Methods:

• Retrospective analysis of RA patients treated with high-dose salicylates versus controls.
• Prospective study of renal function in healthy individuals and RA patients starting therapeutic salicylate doses.
• Monitoring urinary concentrating ability and N-acetyl-beta-D-glucosaminidase (NAG) excretion.

Main Results:

• High-dose salicylate use in RA patients correlated with impaired urinary concentrating power and elevated NAG excretion.
• Prospective study showed increased NAG excretion in all salicylate-treated subjects (healthy and RA patients) by day 3, sustained at day 10.
• RA patients exhibited significantly higher NAG levels than healthy subjects.
• Epithelial cell excretion was only transiently elevated.

Conclusions:

• Salicylate treatment induces renal tubular damage.
• The observed renal tubular damage results in minimal functional impairment.
• The findings do not support withholding salicylate treatment due to renal concerns.