Clinical studies on amyloidosis complicated with rheumatoid arthritis--with particular reference to nephropathy.

Twenty-two patients with definite or classical rheumatoid arthritis (RA) who were diagnosed as amyloidosis by biopsy or at autopsy were investigated. The average duration of RA prior to the diagnosis of amyloidosis was 16.5 +/- 12.5 years. The symptoms that led to the diagnosis of amyloidosis were renal symptoms in 11 cases and gastrointestinal symptoms in 5 cases. Urinary protein was positive in 16 cases (73%). The degree of proteinuria varied in each case. Nephrotic syndrome was observed in 5 cases. Azotemia (Cr greater than 1.5 mg/dl) was present in 18 cases (82%). The period from the diagnosis of amyloidosis to death was 3.0 +/- 2.2 years. The causes of death were uremia in 10 cases, heart failure in 2 cases, malignancy in 2 cases, sepsis in 2 cases and others in 2 cases. Thirteen patients were autopsied and the frequency of amyloidosis complicated with RA was 22.0% in autopsied rheumatoid patients. Although nephropathy was present in most cases of amyloidosis complicated with RA, proteinuria and azotemia greatly varied in both degree and course.