RESUMEN
Adults with pulmonary hypertension and polycythemia (N=22) have low levels of plasma antithrombin III (84 ñ 18 vs 98 ñ 13½ for controls, N=35, P<0.005) and protein C (66ñ21 vs 125 ñ 30%, N 8, P<0.0002 but normal levels of total protein S. Data are reported as means ñ SD and percent normal values obtained for pooled plasma from normal healthy adults. Children with the same disorder (N = 6) also had low protein C levels (66 ñ 16 vs 85 ñ 5½, P < 0.025). Total protein S was normal for children, but free protein S was decreased (66 ñ 13 vs 91 ñ 23,, P < 0.02). Since the levels observed in these patients are above those reported for congenital deficiencies, the reduction in plasma levels of anticoagulant proteins may be the result of cronic intravascular coagulation. Furthermore, normal levels of plasminogen and fibrin degradation products suggested a localized disorder or an acquired decrease in fibronolytic activity