In the comments section of our May 24 “HIT Kits” post from Ginger Weeden, “Jack” asked, “Has any research been done on how long a patient with a positive HIT test stay positive before turning negative?”
Jack, thank you for your question. The HIT antibody remains 50–80 days after it is first detected, according to Warkentin TE, Kelton JG. Temporal aspects of heparin-induced thrombocytopenia. N Engl J Med 2001; 344:1286–92. You may also want to referenceWarkentin TE, Greinacher A, Koster A, Lincoff A. Treatment and prevention of heparin-induced thrombocytopenia, American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008;133:340–80S. In this article, the authors state:
“Among patients with typical-onset HIT, there is no trend to earlier onset of HIT in those patients with a history of previous heparin exposure. Second, among patients with rapid-onset HIT, preexisting HIT antibodies can be detected in patient blood obtained immediately before the repeat heparin exposure that caused the rapid-onset HIT. Moreover, in rapid-onset HIT, there is a strong association with recent (<100 days), rather than remote (>100 days) prior heparin exposure. Third, HIT antibodies are transient, with the median time to antibody disappearance of 50 to 80 days, depending upon the assay performed. Fourth, in situations when heparin has been accidentally or deliberately readministered in situations when HIT antibodies were no longer present, recurrence of HIT antibodies usually did not occur.”
I hope this is helpful, please contact Fritsma Factor if you would like to expand on your question. Geo
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