Serum amyloid A protein concentration in progressive systemic sclerosis (scleroderma).

Serum amyloid A protein (SAA) concentrations were determined in 62 patients with progressive systemic sclerosis (PSS). Forty-seven patients had normal or slightly elevated SAA levels (less than 1000 ng/ml = micrograms/l), while 15 patients had moderately to markedly elevated SAA levels, similar to those observed in active rheumatoid arthritis (RA) (greater than or equal to 1000 ng/ml = micrograms/l). Five patients with PSS had SAA levels corresponding to those observed in amyloidosis secondary to RA. High SAA was associated with more severe skin thickening and diminished cumulative survival at five years. The rarity of amyloidosis secondary to PSS is unlikely to be related to an intrinsic defect in SAA production.