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Pediatric Anemia: Iron Deficiency, Lead & Marrow Failure

Name: Pediatric Anemia: Iron Deficiency, Lead & Marrow Failure
Creator: Veli Bakalov, MD

Milk, paint, and marrow — three roads to a pale toddler

Pediatrics·Hematology & Oncology·5 min read·8 high-yield points·Reviewed by Veli Bakalov, MD @HemeOncBuddy

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Toddler drinking >24 oz/day of cow's milk with microcytosis and a high RDW = iron deficiency; universal hemoglobin screening at 12 months.
Treat with oral elemental iron 3 mg/kg/day (not with milk); a hemoglobin rise ≥1 g/dL after 4 weeks confirms the diagnosis.
Microcytosis with normal RDW, normal or high RBC count, target cells, and Mentzer index <13 = thalassemia trait → hemoglobin electrophoresis, no iron.
Lead: pre-1978 housing, pica, recent immigrants; basophilic stippling, abdominal pain, constipation, and cognitive deficits.
Confirm fingerstick lead with a venous level; ≥3.5 µg/dL → remove the source; ≥45 → oral succimer; ≥70 or encephalopathy → admit for dimercaprol plus CaNa2EDTA.
Diamond-Blackfan anemia: macrocytic pure red cell aplasia in infancy with ↑HbF and thumb anomalies → transfusion in infancy, steroids after about 12 months (chelate if chronically transfused).
Transient erythroblastopenia of childhood: post-viral normocytic reticulocytopenia at ages 1–4 that resolves on its own.
Fanconi anemia: pancytopenia with absent thumbs/radii and café-au-lait spots; diagnose with chromosome breakage testing.

Iron deficiency anemia

Who is at risk. The classic patient is a toddler drinking more than 24 oz of cow's milk a day: milk is iron-poor, fills the child so iron-rich foods are refused, and can cause occult intestinal blood loss from milk-protein colitis. Other risks are prematurity or low birth weight (small stores, rapid growth), exclusive breastfeeding past 4 months without iron supplements, cow's milk before 12 months, and menstrual losses in adolescents.

Screening. Hemoglobin is screened universally at about 12 months with a dietary risk assessment. Iron deficiency impairs cognition and behavior even before anemia develops. At-risk toddlers should have lead tested at the same visit, because the exposures overlap and iron deficiency increases intestinal lead absorption.

Laboratory findings. Low MCV with a high RDW, low ferritin, low transferrin saturation, high TIBC, and often reactive thrombocytosis; the smear shows hypochromic microcytes and pencil cells. Ferritin is an acute-phase reactant and can be falsely normal during infection.

Treatment. Oral ferrous sulfate, 3 mg/kg/day of elemental iron, given between meals with juice rather than milk, plus limiting milk to under 24 oz/day. Reticulocytes rise within about a week, and a hemoglobin rise of at least 1 g/dL after 4 weeks confirms the diagnosis. Continue for 2–3 months after hemoglobin normalizes to replete stores.

No response to iron: check adherence first, then look for ongoing blood loss, celiac disease, thalassemia trait, or lead poisoning.

Iron deficiency vs thalassemia trait

Thalassemia trait. Mild anemia with a strikingly low MCV, a normal RDW, a normal or high RBC count, target cells, and normal iron studies. The Mentzer index (MCV divided by RBC count in millions) below 13 favors thalassemia trait; above 13 favors iron deficiency. β-thalassemia trait is confirmed by hemoglobin electrophoresis showing HbA2 above 3.5%; α-thalassemia trait has a normal electrophoresis after infancy. Empiric iron is not given, since it adds nothing and can cause overload.

Microcytic anemia in children

Feature	Iron deficiency	Thalassemia trait	Lead poisoning
RDW	High	Normal	Often high
RBC count / Mentzer	Low / >13	Normal or high / <13	Variable
Smear	Hypochromia, pencil cells	Target cells	Basophilic stippling
Key test	Ferritin; response to iron	Hemoglobin electrophoresis	Venous blood lead level

Coexisting iron deficiency lowers HbA2 and can mask β-thalassemia trait; replete iron, then repeat electrophoresis.

Lead poisoning

Exposure. Dust and chips from deteriorating paint in pre-1978 housing, worst during renovation, are the main source. Others include contaminated soil, imported spices and cosmetics (kohl or surma), folk remedies (azarcon, greta), glazed ceramics, old pipes, and parents' occupations such as battery work or construction. Risk is highest in 1–2-year-olds with hand-to-mouth behavior or pica, recent immigrants, refugees, and international adoptees; Medicaid-enrolled children are tested at 12 and 24 months.

Toxicity. Lead inhibits ALA dehydratase and ferrochelatase, raising zinc protoporphyrin, and pyrimidine 5′-nucleotidase, producing basophilic stippling; the anemia is microcytic. Children develop abdominal pain, constipation, anorexia, irritability, and permanent cognitive and behavioral deficits, with no known safe level. Very high levels cause encephalopathy (vomiting, ataxia, seizures, coma) and dense metaphyseal "lead lines" on radiographs.

Diagnosis. A fingerstick sample can be falsely high from skin contamination, so confirm with a venous level. An abdominal radiograph is obtained if paint chips may have been swallowed.

Venous lead ≥3.5 µg/dL (CDC reference value)Environmental history, source identification and removal, iron- and calcium-rich diet, developmental monitoring, repeat testing.
≥45 µg/dLOral succimer (DMSA), started only after the child is removed from the contaminated environment.
≥70 µg/dL or any encephalopathyHospitalize for IM dimercaprol (BAL) plus IV CaNa2EDTA, with seizure and intracranial pressure management.

Give dimercaprol before EDTA so lead is not mobilized into the brain; dimercaprol is formulated in peanut oil and is avoided in peanut allergy.

Marrow failure syndromes

Diamond-Blackfan anemia. A congenital pure red cell aplasia caused by ribosomal protein gene defects such as RPS19. It presents in the first year, often by 2–3 months, with macrocytic anemia, reticulocytopenia, elevated HbF and erythrocyte adenosine deaminase, and normal white cells and platelets. About half have anomalies: triphalangeal thumbs, cleft palate, short stature. Treatment is red cell transfusion in the first year, then a corticosteroid trial (usually deferred until about 12 months of age); patients who stay on chronic transfusion need iron chelation; stem cell transplant is curative, and the risk of AML and osteosarcoma is increased.

Transient erythroblastopenia of childhood. An acquired, post-viral suppression of red cell production in previously healthy children aged 1–4. Pallor develops gradually; the anemia is normocytic with reticulocytopenia, normal HbF, and no anomalies. Recovery occurs within 1–2 months, with reticulocytes returning first; management is observation, with transfusion only for cardiovascular compromise.

Fanconi anemia. An autosomal recessive DNA-repair defect (FANCA most common) causing progressive pancytopenia, usually by age 5–10, often preceded by macrocytosis. Anomalies include absent or hypoplastic thumbs and radii, short stature, café-au-lait spots, microcephaly, and renal malformations. Diagnosis is by chromosome breakage testing with diepoxybutane or mitomycin C. Risks of AML and squamous cell cancers are high; stem cell transplant treats the marrow failure. TAR syndrome (thrombocytopenia with absent radii) spares the thumbs.

Pediatric marrow failure

Feature	Diamond-Blackfan	TEC	Fanconi
Age	<1 year	1–4 years	Usually 5–10 years
Cell lines	Red cells only	Red cells only	Pancytopenia
MCV / HbF	High / high	Normal / normal	High / often high
Anomalies	Triphalangeal thumbs, cleft palate	None	Absent thumbs and radii, café-au-lait spots
Management	Transfusion in year 1, then steroids; chelation if chronically transfused; HSCT	Observation	HSCT; cancer surveillance