Usefulness of the delta neutrophil index as an ancillary test in the emergency department for the early diagnosis of suspected acute promyelocytic leukemia.

The delta neutrophil index (DNI) reflects the fraction of circulating immature granulocytes. We evaluated the usefulness of DNI values in patients with acute myeloid leukemia (AML) to distinguish the acute stage of acute promyelocytic leukemia (APL). We analyzed patients retrospectively who were first diagnosed with AML upon admission to the emergency department (ED). Thirty of the 134 patients (22.4%) were diagnosed with APL on ED admission. The univariate analysis and multivariate logistic regression models revealed that DNI values differed significantly between APL and non-APL AML patients on days 0, 1 and 2. Increased predictability for APL was associated with a DNI greater than 24.2% on ED admission, greater than 23.6% on day 1 and greater than 44% on day 2 in patients with AML. DNI values of patients with AML could discriminate the acute stage of APL from AML for immediate initiation of all-trans retinoic acid therapy.