Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (391 page)

   Hypersplenism

   Drug-related thrombocytopenia in the mother

   Hypersplenism in neonates with an an enlarged spleen

   Necrotizing enterocolitis

   Laboratory studies are directed to the underlying condition and monitoring the platelet counts.

Decreased Production

   Genetic disorders: thrombocytopenia-absent radius syndrome; congenital megakaryocytic thrombocytopenia; Fanconi anemia; certain chromosome abnormalities; congenital platelet disorders; lipid storage diseases

   Acquired causes: bone marrow diseases (neonatal leukemia, neuroblastoma); toxic injury to megakaryocytes due to drugs or infections; neonates whose mothers have preeclampsia; birth asphyxia; following exchange transfusion

   Laboratory Findings

   Serial platelet counts

   Maternal studies for thrombocytopenia

   DIC screening in infants at risk for DIC

PSEUDO (SPURIOUS) THROMBOCYTOPENIA

   Definition

A false decrease in reported platelet counts. It may be due to:

   Platelet clumping induced by collection of blood in EDTA (the routine anticoagulant used for CBC); it is the most common cause for spurious thrombocytopenia. In a good laboratory, the technicians observe all CBC tubes flagged for low platelets for the presence of clots and review stained peripheral blood smear (PBS) for clumps.