NAPLEX 2026 Sickle Cell Anemia

Sickle cell anemia

Homozygous SCD with abnormal hemoglobin S/HbS.

SCD genetic cause

Mutation in genes encoding hemoglobin.

Normal RBC lifespan ; Sickled RBC lifespan

About 120 days ; 10-20 days

SCD symptom onset: Usually around ____ after birth when fetal hemoglobin declines. ____ protects infants by inhibiting sickling.

2-3 months ; Fetal hemoglobin/HbF

SCD contraception pearl

Avoid estrogen/progestin-only contraceptives per section due to stroke risk; levonorgestrel IUDs and barrier methods preferred.

Chest pain with pulmonary infection/infiltrate in SCD; life-threatening and leading cause of death is called

Acute chest syndrome.

Functional asplenia usually occurs within ____ year of life.

first year of life.

SCD infection organisms

Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis; also Salmonella and others.

SCD fever counseling

Seek immediate medical attention for temperature >101.3°F.

Routine childhood vaccines in SCD

Hib and pneumococcal conjugate vaccine such as PCV15/Vaxneuvance or PCV20/Prevnar 20.

Additional functional asplenia vaccines

MenACWY with boosters, MenB, and pneumococcal series if incomplete.

Penicillin prophylaxis in SCD reduces death from invasive pneumococcal infection in young children. Start ____ penicillin in infants who screen positive for SCD at birth. Continue until age ____ in most children.

twice-daily ; five years old

Transfusion indications (3)

Stroke, acute chest syndrome, and severe anemia may require transfusion.

Post-infusion Hgb should be no higher than ____. Chelation agents can be used for excess

10 g/dL

Deferasirox brands

Exjade, Jadenu; oral iron chelator.

Deferiprone brand

Ferriprox; oral iron chelator.

Mild-moderate SCD pain

Rest, fluids, warm compresses, and NSAIDs or acetaminophen when appropriate.

Severe VOC pain

Requires rapid severity-guided therapy, often IV opioids or patient-controlled analgesia/PCA.

Hydroxyurea brands

Droxia, Hydrea, Siklos, Xromi.

Hydroxyurea is a primary ____-_____ therapy for SCD. Stimulates HbF production, reducing sickling. It reduces acute pain crises, acute chest syndrome, and transfusion need; improves quality of life.

disease-modifying

Hydroxyurea adult indication

Adults with ≥3 moderate-severe pain crises, acute chest syndrome, or chronic pain affecting quality of life.

Hydroxyurea pediatric recommendation

Recommended for all pediatric patients age 9 months-18 years regardless of disease severity.

Hydroxyurea max dose

35 mg/kg/day.

Hydroxyurea weight for dosing

Use ideal body weight or actual body weight, whichever is less.

Hydroxyurea renal adjustment

Dose adjustment required if CrCl <60 mL/min.

Hydroxyurea boxed warning

Warnings

Monitoring

Myelosuppression and malignancy such as leukemia/skin cancer.

Fetal toxicity, avoid live vaccines, skin ulcers, macrocytosis, pulmonary toxicity

CBC with diff q2-4 weeks during initiation/titration, then q2-3 months once stable; (tox = anc <2,000 cells/mm³)

Hydroxyurea hold criteria

Hold if ANC <2,000 or platelets <80,000; restart at 2.5 mg/kg/day lower after recovery.

Hydroxyurea contraception ; breastfeeding ; handling

Contraception required for males and females during treatment and 6-12 months after stopping ; do not ; wear gloves and don’t open capsules

To prevent macrocytosis _____ supplementation recommended

Folic acid

Hydroxyurea memory hook

Hydroxyurea raises HbF but lowers counts; monitor CBC and avoid pregnancy/live vaccines.