Primary systemic amyloidosis--a diagnostic primer.

Primary systemic amyloidosis (immunoglobulin light chain-derived) (AL) is an uncommon dysproteinemia with highly varied initial clinical manifestations. Among 153 patients with this disorder, the median survival was 20.4 months (5-year survival, 19.6%). The worst outcome was associated with overt congestive heart failure (median survival, 7.7 months; 5-year survival, 2.4%). The patients with the best outcome were those who had amyloid neuropathy without associated cardiac or renal involvement (median survival, 39.7 months; 5-year survival, 31.6%). Serum protein electrophoresis and immunoelectrophoresis are the most important tests because a monoclonal protein can be detected in almost two-thirds of the patients. When screening of both serum and urine is performed, a monoclonal protein is found in 86% of patients. Such screening is helpful if primary systemic amyloidosis is to be detected and treated early.