Clinical and Morphological Manifestations and Risk Factors for Renal Involvement in Rheumatoid Arthritis

Abstract

Background: Renal involvement is an underrecognized but clinically important extra-articular manifestation of rheumatoid arthritis (RA). Objectives: To review the clinical and morphological manifestations and identify major risk factors for renal involvement in RA. Materials and Methods: Published clinical and renal biopsy studies were reviewed, focusing on epidemiology, clinical presentation, histopathological patterns, pathophysiological mechanisms, and risk factors associated with renal impairment. Results: Reported prevalence of renal involvement ranges from approximately 1% to more than 50%, depending on diagnostic criteria and detection methods. Renal biopsy studies identify mesangial and immunoglobulin A-dominant glomerulonephritis, membranous nephropathy, and AA amyloidosis as major histopathological patterns. Clinically, renal involvement most commonly presents with microalbuminuria or subnephrotic proteinuria, while nephrotic syndrome, haematuria, and declining estimated glomerular filtration rate may also occur. Older age, hypertension, dyslipidaemia, prolonged and highly active RA, extra-articular manifestations, and nephrotoxic drug exposure are important risk factors. Conclusion: Renal involvement in RA has diverse clinical and morphological manifestations. Early screening, monitoring of renal function and proteinuria, effective control of systemic inflammation, and management of modifiable risk factors are essential for early detection and nephroprotection.