From the Guidelines
Proteinuria can indeed occur in patients with rheumatoid arthritis (RA), resulting from kidney involvement, which affects approximately 5-50% of RA patients. The most common kidney manifestation in RA is secondary amyloidosis, where abnormal protein deposits damage kidney tissue, leading to proteinuria that can progress to nephrotic syndrome. Membranous nephropathy and mesangial glomerulonephritis can also occur in RA patients, causing protein leakage. Additionally, medications used to treat RA, particularly disease-modifying antirheumatic drugs (DMARDs) like gold compounds, penicillamine, and nonsteroidal anti-inflammatory drugs (NSAIDs), can cause drug-induced nephropathy with proteinuria as a symptom.
Some key points to consider in the management of proteinuria in RA patients include:
- Regular urinalysis to monitor for proteinuria, especially in patients on nephrotoxic medications
- Further evaluation with quantitative urine protein tests, kidney function tests, and possibly renal biopsy if proteinuria is detected
- The use of ACE inhibitors (ACEi) or angiotensin receptor blockers (ARB) to reduce proteinuria, as recommended by the KDIGO guidelines 1
- The goal of therapy should be to achieve a proteinuria level of less than 0.5-0.7 g/24 hours, as suggested by the EULAR/ERA-EDTA recommendations 1
- The MEST score, which includes mesangial hypercellularity, segmental glomerulosclerosis, endocapillary hypercellularity, and tubular atrophy/interstitial fibrosis, can be used to predict kidney outcome in patients with IgAN, but its use in RA patients is not well established 1
In summary, proteinuria is a potential complication of RA, and its management should involve regular monitoring, further evaluation if necessary, and the use of ACEi or ARB to reduce proteinuria, with the goal of achieving a proteinuria level of less than 0.5-0.7 g/24 hours.
From the Research
Proteinuria in Rheumatoid Arthritis
- Proteinuria is a common symptom of renal disease in patients with rheumatoid arthritis (RA), with studies showing that 55% of RA patients exhibit proteinuria as a symptom of renal disease 2.
- The presence of proteinuria in RA patients can be attributed to various factors, including drug therapy, vasculitis, and rheumatoid nephropathy, which is mediated by immunological inflammation and nephrotoxic effects of certain drugs 3.
- Renal biopsy findings in RA patients with proteinuria have revealed various histopathological lesions, including amyloidosis, glomerulonephritis, interstitial nephritis, and mesangial proliferative glomerulonephritis 3, 4.
Types of Proteinuria
- Studies have shown that tubular and mixed proteinuria are more frequent than glomerular proteinuria in RA patients 2.
- The type of proteinuria can vary depending on the underlying renal lesion, with amyloidosis being a common cause of nephrotic-range proteinuria in RA patients 3, 5.
Clinical Implications
- Proteinuria is an important marker of renal disease in RA patients, and its presence can indicate underlying renal damage or disease 2, 6.
- Screening for renal disease in RA patients should include sensitive methods to detect proteinuria, as well as regular monitoring of renal function and urine analysis 2, 6.
- Treatment of RA patients with proteinuria should involve a multidisciplinary approach, including immunosuppressive therapy, strict control of hypertension, and avoidance of nephrotoxic drugs 3, 5, 6.