Changes in Blood Test Indices of Infants With Down Syndrome‐Associated Transient Abnormal Myelopoiesis

Background Approximately 20% of infants with Down syndrome‐associated transient abnormal myelopoiesis (TAM) die at an early age, mainly because of liver failure. Objective To identify post‐diagnosis changes in blood test indices that could predict TAM‐related deaths as early as the postnatal period. Methods/Results This was a single‐center retrospective study. Of the 505 children with Down syndrome admitted to our hospital from 1992 to 2024, we studied 12 infants with TAM‐related death and 39 survivors. In the death and survival groups, the median gestational ages were 34.9 and 37.1 weeks, respectively ( p = 0.146). At birth, the white blood cell (WBC) counts were 99.2 and 41.7 × 10 9 /L ( p = 0.027), and the serum direct bilirubin (D‐Bil) concentrations were 20 and 17 µmol/L ( p = 0.45), respectively. After the first week of age, the WBC counts, blast percentages, platelet counts, and serum alanine aminotransferase and aspartate aminotransferase concentrations were similar between the groups. At 1 week of age, the serum D‐Bil concentrations were 32 and 21 µmol/L ( p = 0.007), respectively. At 2 weeks, they were 94 and 27 µmol/L ( p < 0.001), respectively. The area under the receiver operating characteristic curve for the ability of serum D‐Bil at 2 weeks to predict death was 0.94, with a threshold of ≥51 µmol/L (approximately 3.0 mg/dL) yielding a sensitivity of 1.00 and a specificity of 0.78. Conclusion A serum D‐Bil concentration of ≥51 µmol/L at 2 weeks of age may serve as a useful predictor of TAM‐related death.