Blood disorders in children fall into three groups: red cell problems (anemias), bleeding disorders, and bone marrow failure. Normal hemoglobin changes with age — high at birth, lowest at about 2–3 months ("physiologic nadir"), then rising. WHO (2024) anemia cutoffs: Hb below 10.5 g/dL (105 g/L) at 6–23 months, below 11 g/dL (110 g/L) at 24–59 months, below 11.5 g/dL (115 g/L) at 5–11 years, and below 12 g/dL (120 g/L) at 12–14 years. Leukemia is covered in "Childhood Cancer and Treatment"; adult anemias and transfusion in the Medical-Surgical topic "Anemias."

Iron-deficiency anemia (IDA) — the most common nutritional disorder of childhood. Iron stores from pregnancy last about 4–6 months in term infants (less in preterm infants). Peaks: 6–24 months and adolescence (growth spurt, menstruation). Causes: exclusive breastfeeding beyond 4–6 months without iron-rich foods, cow's milk before 12 months or too much cow's milk in toddlers (low iron, blocks iron absorption, and can cause occult intestinal blood loss), and poor diet. Result: microcytic, hypochromic anemia. Even without anemia, iron deficiency in early childhood can impair neurodevelopment.

Sickle cell disease (SCD) — autosomal recessive. Hemoglobin S polymerizes when deoxygenated, making red cells rigid and sickle-shaped; they block small vessels (vaso-occlusion) and hemolyze early. Triggers: hypoxia, dehydration, infection, fever, cold, acidosis, stress. Symptoms begin around 4–6 months as fetal hemoglobin (HbF) falls. Repeated splenic infarction causes functional asplenia in early childhood → high risk of sepsis from encapsulated bacteria (Streptococcus pneumoniae). Sickle cell trait (HbAS) is usually symptom-free. (Consistent with Medical-Surgical "Anemias.")

Thalassemia — inherited reduced production of globin chains. Beta-thalassemia major causes severe anemia from about 6 months, bone marrow expansion (frontal bossing, maxillary overgrowth), and hepatosplenomegaly. Treatment with regular transfusions leads to iron overload (heart, liver, endocrine organs) — the main long-term cause of death.

G6PD deficiency — X-linked enzyme defect; oxidant stress (fava beans, naphthalene mothballs, certain drugs, infection) triggers acute hemolysis.

Hemophilia — X-linked recessive deficiency of factor VIII (hemophilia A, about 80–85%) or factor IX (hemophilia B); affects mainly boys, mothers are carriers. Severity follows factor level: severe below 1%, moderate 1–5%, mild 5–40%. Hallmark: bleeding into joints (hemarthrosis) — knees, ankles, elbows — and muscles; repeated joint bleeds destroy cartilage (hemophilic arthropathy).

Immune thrombocytopenia (ITP) — autoantibodies destroy platelets, often 1–4 weeks after a viral infection in a previously healthy child aged 2–6 years. Most children recover within 6 months regardless of treatment.

Aplastic anemia — bone marrow failure with pancytopenia (anemia, neutropenia, thrombocytopenia); inherited or acquired (drugs, viruses, immune).

IDA

• Oral elemental iron about 3 mg/kg/day (often once daily), continued for about 3 months after Hb normalizes to refill stores
• Correct the diet: limit cow's milk, add iron-rich foods; treat blood loss
• Prevention: iron-fortified formula; breastfed infants receive iron 1 mg/kg/day from 4 months until iron-rich foods are eaten; no cow's milk before 12 months; toddlers no more than about 16–24 oz (480–720 mL) of milk daily

SCD

• Penicillin prophylaxis from about 2 months until at least 5 years; all routine vaccines plus pneumococcal and meningococcal vaccines; yearly influenza
• Fever 38.5 °C (101.3 °F) or higher is an emergency: CBC, blood culture, and IV ceftriaxone promptly
• Hydroxyurea offered from 9 months of age (increases HbF, reduces pain crises and acute chest syndrome)
• Pain crisis: rapid analgesia (first dose within about 60 minutes, often IV opioids) plus hydration; oxygen only if hypoxemic; avoid meperidine
• Acute chest syndrome: antibiotics, oxygen, incentive spirometry, transfusion
• Stroke: emergency exchange transfusion; chronic transfusion for prevention when TCD is abnormal
• Curative options: stem cell transplant, gene therapy

Thalassemia major — transfusion every 3–5 weeks; iron chelation when ferritin rises; folic acid; splenectomy in some (then vaccines and penicillin); stem cell transplant or gene therapy.

Hemophilia

• Replace the missing factor promptly — ideally at home at the first sign of bleeding; regular prophylaxis is standard for severe disease
• Emicizumab (hemophilia A): subcutaneous prophylaxis every 1–4 weeks; it does not treat an acute bleed
• Desmopressin for mild hemophilia A; tranexamic acid for mouth and nose bleeds (not for hematuria — clots can block the ureters)
• Inhibitors (antibodies against factor) need bypassing agents

ITP — observation for children with no or mild bleeding (skin only), regardless of platelet count; for bleeding: short course of corticosteroids or IVIG; thrombopoietin receptor agonists for chronic ITP.

Aplastic anemia — stem cell transplant, or immunosuppression with antithymocyte globulin (ATG) and cyclosporine; transfusion and infection support.

Drug safety (doses weight-based and verified against a pediatric reference)

Listed in priority order.

1. Life-threatening complications first
   • SCD: assess respiratory status and SpO₂ and neurologic signs first; report chest pain, hypoxemia, focal weakness, sudden pallor with enlarging spleen, or fever at once
   • Hemophilia: any head injury, neck or throat swelling, or abdominal pain is treated as a serious bleed — give factor and notify immediately
   • Fever with neutropenia (marrow failure, chemotherapy): blood cultures and IV antibiotics within 60 minutes
2. Oxygenation and perfusion — rest, oxygen if hypoxemic; transfuse as ordered using the same safety checks as adults (two identifiers, normal saline only, stay for the first 15 minutes, finish within 4 hours)
3. Pain and hydration (SCD crisis) — rapid analgesia on schedule with reassessment; IV and oral fluids about 1–1.5 times maintenance (avoid overload); warmth, no cold packs; incentive spirometry every 1–2 hours while awake
4. Bleeding prevention and control
   • No IM injections (use SC or oral; vaccines SC where possible, or IM with the smallest needle and 5 minutes of firm pressure); avoid rectal temperatures; apply pressure for at least 5–10 minutes after venipuncture
   • Hemophilia joint bleed: give factor first, then rest, ice, compression, and elevation; immobilize briefly, then physiotherapy to restore motion
   • ITP or low platelets: soft toothbrush, avoid contact sports and rough play, no NSAIDs
5. Infection prevention — hand hygiene; penicillin adherence in SCD; for severe neutropenia, avoid sick contacts, practice safe food handling (washed produce, fully cooked meat and eggs)
6. Growth, development, and family support — chronic illness, genetic counseling, school plans

• Iron-rich foods: red meat, liver, fish, poultry, beans, iron-fortified cereals, dark green vegetables; eat vitamin C foods with them; limit milk to 16–24 oz a day in toddlers
• SCD: fluids every day, avoid temperature extremes, high altitude, and exhausting exercise; take the child's temperature when ill — 38.5 °C (101.3 °F) or higher means go to the hospital now; learn to feel the spleen and seek care for sudden pallor or a larger spleen; never skip penicillin
• Hemophilia: medical ID; home factor infusion; treat early at the first "tingling" or warmth in a joint; safe activities — swimming, cycling with a helmet; avoid contact sports (football, wrestling); regular dental care with soft brush; genetic counseling for carrier testing of female relatives
• ITP: most children recover; avoid aspirin and ibuprofen; soft toothbrush; helmets; report headache, vomiting, blood in urine or stool, or heavy nosebleeds
• Thalassemia: chelation adherence is life-saving; do not take iron supplements; hepatitis B vaccination
• G6PD deficiency: avoid fava beans, mothballs, and listed drugs

• IDA: low Hb, low MCV, low ferritin, high TIBC; cow's milk excess is the classic toddler cause
• Iron: between meals with vitamin C, not with milk; straw or dropper to protect teeth; black stools normal; keep locked away
• SCD: dehydration, hypoxia, cold, and infection trigger sickling; fever 38.5 °C or higher = emergency (functional asplenia)
• SCD priorities: respiratory and neurologic assessment; rapid analgesia plus hydration; no cold packs
• Penicillin prophylaxis to age 5; TCD yearly from 2 to 16; hydroxyurea from 9 months
• Thalassemia: transfusion causes iron overload → chelation; do not add iron
• Hemophilia: X-linked, prolonged aPTT, normal PT and platelets; earliest joint bleed sign = tingling or warmth; factor first, then rest, ice, compression, elevation; no IM injections, no aspirin
• ITP: petechiae after a viral illness; observe if bleeding is mild; avoid contact sports and NSAIDs; steroids cause moon face
• Cyclosporine → nephrotoxicity (monitor creatinine and electrolytes)