Heparin-induced thrombocytopenia: confirmation of diagnosis with in vitro methods

Abstract

Profound thrombocytopenia developed in a patient during treatment with heparin for venous thrombosis. The platelet count increased toward normal when heparin administration was stopped, but fell abruptly when the drug was again given. Platelet aggregation occurred when heparin was added to the patient's platelet-rich plasma, or to normal platelets plus the patient's serum. This serum also effected release of 3H- serotonin from normal platelets. This pattern of aggregation was clearly different from that occasionally caused by heparin in a control population. The data is consistent with an effect of heparin on platelets, possibly mediated by on immune mechanism.

Heparin‐induced platelet aggregation in anorexia nervosa and in severe peripheral vascular disease

“…Thrombocytopenia and thromboembolism are well recognized complications of heparin therapy [I-61. These complications are considered to be mediated by an idiosyncratic immunological mechanism which renders platelets hypersensitive to heparin [1][2][3][4][5][6]. However, some patients developed consumptive thrombocytopenia following heparin therapy within hours of initiating treatment and without prior exposure to heparin [7].…”

Heparin‐induced thrombocytopenia and recurrent thromboembolism

“…Presumably, this effect is different from the heparindependent aggregating factor noted in these patients. Similarly, some studies have demonstrated enhanced serotonin release from normal platelets incubated with patient sera or plasma [14,. The PF3 immuno-injury test for platelet antibodies has also been positive in some patients [15,171 .…”

“…Laake et a1 [29] PATHOPHYSIOLOGY Enhanced peripheral destruction of platelets is believed to be the mechanism of thrombocytopenia in these cases based upon bone marrow examinations (Table I) and the demonstration of a shortened platelet survival [24], but the reason for this remains unsettled. Many investigators have detected a heparin-dependent platelet aggregating factor (PAF) in the blood of patients with this disorder [14,15,19,, while others have not [30,33]. Heparin has been shown to produce platelet aggregation in vitro, but at very high doses [34] .…”

“…Cases are more commonly recognized as a result of more frequent platelet determinations. Several investigators [12,14,15,17,[19][20][21] have identified immunologic alterations as the mechanism responsible for the reduction in platelet count.…”

Drug‐induced immune thrombocytopenia

“…The incidence of thrombocytopenia is as high as 30% with beef lung heparin preparations [69] but appears much lower with heparin derived from porcine intestine [70,71]. Considerable in vitro evidence is accumulating for the presence of heparin-dependent antiplatelet antibodies in many of these patients [72][73][74][75][76], but not in all [77]. A separate review of heparin thrombocytopenia will appear soon in this journal.…”