Chapter 139: Anemia in the Newborn Infant

Physiologic nadir · Blood loss · Hemolysis · Underproduction · Hemoglobinopathies · Transfusion thresholds · Diagnostic algorithm
🩸 Key fact: Hemoglobin nadir at 6-10 wk (term) or 4-8 wk (preterm). Transfusion thresholds: restrictive strategy reduces exposure.

🩸 Neonatal Anemia: Core Concepts

📊 Physiologic nadir
Term: Hgb 9-11 g/dL at 6-10 wk. Preterm: Hgb 8-9 g/dL at 4-8 wk. Due to increased O2 delivery, shortened RBC lifespan (60d vs 120d).
💧 Blood loss anemia
Iatrogenic (phlebotomy) most common. Obstetric: abruption, fetomaternal hemorrhage, twin-twin transfusion, occult GI bleed.
💥 Hemolytic anemia
Immune (Rh, ABO), membrane defects (spherocytosis), enzyme defects (G6PD, pyruvate kinase), hemoglobinopathies (α-thalassemia).
🦴 Underproduction
Anemia of prematurity, Diamond-Blackfan, Fanconi, TORCH infection, parvovirus B19, congenital leukemia.
🩸 Transfusion thresholds
Restrictive: Hgb 7-11 g/dL depending on age and respiratory support. 10-20 mL/kg RBCs raises Hgb ~1 g/dL per 5 mL/kg.
🔬 Key labs
CBC, reticulocyte count, smear, Coombs test, bilirubin, maternal blood type, Kleihauer-Betke (fetomaternal hemorrhage).
⚡ Diagnostic algorithm: Reticulocytes low → underproduction (congenital, infection). Reticulocytes high → Coombs positive (immune) vs negative (membrane/enzyme).

🔍 Approach to the anemic newborn: blood loss vs hemolysis vs underproduction

1
History – Obstetric complications (abruption, placenta previa, twin-twin transfusion). Family history (spherocytosis, G6PD, thalassemia).
2
Physical exam – Pallor, tachycardia, hypotension (acute blood loss). Hepatosplenomegaly (hemolysis, infection). Petechiae (thrombocytopenia, DIC).
3
Initial labs – CBC, reticulocyte count, bilirubin (indirect hemolysis), smear, Coombs test, blood type (mother & infant).
4
Interpret reticulocyte count – Low (<5%) → underproduction (congenital, parvovirus, anemia of prematurity). High (>5%) → hemolysis or blood loss.
5
If hemolysis + Coombs negative – smear for spherocytes (hereditary spherocytosis), bite cells (G6PD), elliptocytes, or sickled cells. Enzyme assays, hemoglobin electrophoresis.

📋 Stepwise management of neonatal anemia

1
Stabilize acute blood loss – Volume resuscitation (10-20 mL/kg NS or O-neg blood). Identify source (placental abruption, fetomaternal hemorrhage, twin-twin).
2
Hemolytic anemia management – Phototherapy for hyperbilirubinemia, IVIG for immune hemolysis, exchange transfusion if severe. Folic acid supplementation.
3
Anemia of prematurity – Minimize phlebotomy (microtainers, in-line monitors). Erythropoietin (limited benefit). Transfusion thresholds: restrictive strategy (Hgb 7-11 g/dL).
4
Congenital hypoplastic anemia – Refer to hematology: Diamond-Blackfan (steroids, transfusions), Fanconi (transplant).
5
Iron deficiency – Uncommon in newborn (acquired from chronic fetal-maternal bleeding). Supplement 3-6 mg/kg/day if diagnosed.
📌 Transfusion threshold (restrictive, per Kirpalani 2020): wk1: Hgb 11 g/dL (with resp support) or 10 g/dL (without). wk2: 10/8.5. wk3: 8.5/7.0.

🧠 Rapid reflex prompts – Neonatal anemia

📌 Most common cause of anemia in VLBW infant?
Iatrogenic phlebotomy (anemia of prematurity).
📌 First test for fetomaternal hemorrhage?
Kleihauer-Betke test (or flow cytometry).
📌 Coombs-positive hemolytic anemia differential?
Rh or ABO incompatibility, minor antigens.
📌 Coombs-negative hemolytic anemia + spherocytes?
Hereditary spherocytosis.
📌 Microcytic anemia in a term newborn?
Alpha-thalassemia (hemoglobin H disease, Bart's hydrops).
📌 Physiologic nadir timing in term vs preterm?
Term: 6-10 wk; Preterm: 4-8 wk (more severe).