Heparin-induced thrombocytopenia.

Abstract

There are two types of heparin-induced thrombocytopenia. Type I is more common, has an early onset, and is mild, transient, and benign. Type I is due to direct heparin-induced platelet aggregation and is rarely associated with thromboembolic sequela. Type II is infrequent, has a late onset, and is more severe. Type II is due to an immune-mediated platelet aggregation caused by IgG and IgM that becomes bound to platelets. In Type II, the antibody titers decline over several months; however, early reexposure can result in a catastrophic secondary immune response. Frequently, Type II is associated with life-or limb-threatening thromboembolic complications (white clots), including stroke. {Stroke 1989;20:1449-1459)

Heparin-Induced Thrombocytopenia

“…22 Subsequent in vitro studies have demonstrated no difference. 23 Although an increased number of heparin exposures does not significantly increase the risk of developing HIT II, it may, as with other forms of drug-induced thrombocytopenia, contribute to an earlier onset after repeat administration.24…”

Cerebral venous thrombosis due to heparin-induced thrombocytopenia.

“…On the eleventh day of heparin treatment, her platelet count dropped from 521,000/mm 3 to 50,000/ mm 3 . On the same day, she became disoriented and lethargic, without focal abnormalities.…”

“…On admission in May of 1988, her temperature was 37.3° C. Her erythrocyte count was 5.3x 10 6 /mm 3 , her leukocyte count was 17,500/mm 3 , and her platelet count was 687,000/mm 3 . Her hemoglobin concentration was 13.6 g/100 ml, and her hematocrit was 41%.…”

“…Polycythemia vera had been diagnosed 4 years earlier, at which time she had 10,900 leukocytes/mm 3 , 5.8xlO 6 erythrocytes/mm 3 , 584,000 platelets/mm 3 , a hemoglobin concentration of 17.1 g/100 ml, and a hematocrit of 51%. She was initially treated with P-32; thereafter, her hematocrit was maintained at approximately 40% with phlebotomies.…”

Thrombozytopenie bei einem Patienten nach perkutaner Koronarintervention

“…"white clot syndrome". Während nachweisbare Anti-PF-4-Antikörper oder der positive HIPA-Test die Diagnose bestätigen, gibt es bislang keinen Test, der die HIT Typ II mit 100%iger Sicherheit ausschließen kann [2,3]. Wenn beide Tests negativ sind, ist eine HIT Typ II aber unwahrscheinlich.…”