Amyloidosis is a serious complication of rheumatoid arthritis (RA). Amyloidosis, related to RA, mainly results from the deposition of amyloid A protein into the kidney, intestine and heart. Amyloid A protein is derived from serum amyloid A protein, which behaves as an acute-phase reactant.
A 68-year-old woman was diagnosed with RA in June 1994. Because she noticed pitting-edema in her legs in January 1997, and it did not improve in spite of diuretics-administration, she was admitted to our university hospital in April 1998. She was found to have nephrotic syndrome with daily urinary protein of 4.6 g and serum albumin concentration of 1.7 g/dl. Renal biopsy revealed amyloid deposits in her glomeruli and interstitial matrix. Actarit, sulfasalazine, and prednisolone were prescribed to her without any beneficial effects. These DMARDs were then changed to methotrexate, which gave excellent effects not only on joint inflammation but also on nephrotic syndrome in December 1998; daily urinary protein decreased to 1 g, and serum albumin concentration increased to 2.9 g/dl in March 2005, while creatinine clearance did not change remarkably (from 38.4 ml/min to 30.0 ml/min). Meticulous use of methotrexate in renal amyloidosis associated with rheumatoid arthritis could be very effective and powerful in amelioration of arthritis and nephrotic syndrome due to secondary amyloidosis even in the state of decreased creatinine clearance.
