Trisomy 21 is associated with an increased incidence of hematologic disorders such as polycythemia, transient myeloproliferative disorder, and acute leukemia.1 There are only rare reports in the literature of an association with isolated neonatal thrombocytopenia.2-5 Based on consultations for mild thrombocytopenia in otherwise well newborns with trisomy 21, our clinical impression is that this is a common finding. This review compares the incidence of thrombocytopenia in neonates with trisomy 21 with that found in normal full-term newborns.
Methods. Medical records of all children with trisomy 21 undergoing evaluation at Vanderbilt University Medical Center, Nashville, Tenn, from 1985 to 1993 were reviewed (N=110). Thirty-one full-term infants had platelet counts measured within 48 hours of birth. Capillary blood samples were obtained for platelet enumeration, in most instances by heel puncture. Six patients were excluded from study for either neonatal illnesses involving destruction of platelets (ie, disseminated intravascular coagulation, sepsis, and