Abstract
Background Heparin-induced thrombocytopenia (HIT) antibodies activate platelets, monocytes and
neutrophils. Despite these findings, it is unknown whether white blood cell (WBC)
counts, including neutrophils and monocytes, are altered during HIT.
Materials and Methods We evaluated changes in total WBC counts (including WBC subsets), in 50 post-cardiac
surgery patients with serologically confirmed HIT (30 patients with HIT-associated
thrombosis). Daily leukocyte counts were compared with those measured one day prior
to HIT onset; WBC increases were classified as mild (20.0–49.9%), moderate (50.0–99.9%)
or major (≥ 100% increase). We also compared changes in WBC counts in HIT patients
with and without HIT-associated thrombosis, and non-HIT patients with thrombosis.
Results Most (34/50 [68.0%]) patients with HIT developed WBC count increases (mild, 35.3%;
moderate, 44.1%; major, 20.6%). The peak WBC count occurred on day 4 (median) of HIT,
which corresponded to day 10 (median) post-surgery. Absolute neutrophil counts increased
in most patients (38/50 [76.0%]); whereas absolute monocyte counts rose in some patients,
the overall tendency was for the monocyte count to decrease during HIT. Unexpectedly,
we found that the increase in total WBC counts, as well as in neutrophils, was seen
mainly in patients who developed HIT-associated or non-HIT-associated thrombosis;
in contrast, no difference in monocyte levels was seen in patients with or without
thrombosis.
Conclusion Leukocytosis and neutrophilia are commonly observed in patients with HIT, particularly
in patients with HIT-associated thrombosis, as well as non-HIT patients with thrombosis.
Thus, leukocytosis/neutrophilia should not infer automatically a diagnosis of infection
or inflammation, when evaluating thrombocytopenia in heparin-exposed patients.
Keywords
heparin-induced thrombocytopenia - leukocytes - monocytes - neutrophils - thrombosis
