Screening and diagnosis of heparin-induced thrombocytopenia in the pediatric population: A tertiary centre experience

Heparin-induced thrombocytopenia (HIT) is a life-threatening side effect of heparin necessitating immediate heparin discontinuation. A missed diagnosis of HIT carries significant morbidity and mortality, while overdiagnosis may result in unnecessary and potentially harmful use of alternative anticoagulants in the pediatric population. We aimed to determine the proportion of HIT screening tests at our pediatric tertiary care centre ultimately leading to a diagnosis of HIT by functional assay (either lumi-aggregometry or serotonin-release assay). We hypothesized that the frequency of HIT at our centre would be lower than that reported in the literature. We conducted a retrospective review including children aged 0 to 18 years who had HIT testing performed at our centre between 2010 and 2018 (N = 189; 51% female). A screening enzyme immunoassay, if positive, is followed by a functional assay which must be positive to establish the diagnosis of HIT. Data were analyzed to establish trends in demographic and clinical features of patients with a positive HIT screening test. Our primary outcome was the rate of HIT confirmed by functional testing amongst children screened for HIT from 2010 to 2018. There were 233 screening tests performed on 189 distinct patients. Only one patient (0.4%) received a diagnosis of HIT based on functional assay. This patient was a 16-year-old female later found to have a JAK2 mutation. The false positive rate of the enzyme immunoassay was 9.4% (N = 22). There were no positive enzyme immunoassay tests in the neonatal age group (N = 49). These results reinforce that HIT is rare in children. •Heparin-induced thrombocytopenia (HIT) is a life-threatening side effect of heparin.•Treatment for HIT is immediate discontinuation and lifelong avoidance of heparin.•Diagnosis of HIT is based on symptoms and confirmatory laboratory testing.•HIT is rare in children, occurring in 0.4% of those tested at our pediatric centre.