Clues Pointing TO This Diagnosis

Known diagnosis from newborn screening ("since she was three days old") — SCD is identified by universal US newborn screening, consistent with a lifelong HbSS diagnosis
Acute, severe, sudden-onset pain in chest, back, and legs — extremities, chest, and back are the most common vaso-occlusive crisis (VOC) sites
Cold exposure and dehydration as precipitants — dehydration, hypoxia, cold, infection, and physical/emotional stress are recognized VOC triggers
Physical/emotional stress (exams, exhaustion) preceding the crisis — stress and physical exhaustion can precipitate VOC
Pain she recognizes as typical vaso-occlusive crisis — patient report that location/intensity/duration match prior crises supports uncomplicated VOC
Young adult (age 24) with recurrent lifelong pain episodes — VOCs begin in infancy and recur throughout life in HbSS
On hydroxyurea for prevention — hydroxyurea is first-line disease-modifying therapy that reduces VOC and acute chest syndrome frequency
History framed around acute chest syndrome, stroke, avascular necrosis, kidney, and eye complications — these are the classic chronic/acute complications of SCD
Folic acid daily and prior childhood penicillin prophylaxis with pneumococcal/meningococcal vaccination — standard SCD preventive care reflecting functional asplenia
Vaso-occlusive mechanism (HbS polymerization → rigid cells → small-vessel occlusion) matching her described pathophysiology

Why It's NOT the Similar Diseases

NOT sickle cell trait (HbAS) — persons with trait do not experience typical VOCs; Josephine has a lifelong disease phenotype with recurrent crises
NOT another hemolytic anemia (e.g., hereditary spherocytosis or G6PD deficiency) — these do not cause recurrent vaso-occlusive bone/chest pain with HbS on newborn screening
NOT a primary bone/joint infection (osteomyelitis or septic arthritis) — her pain is multifocal (chest, back, legs) and matches prior VOCs rather than a single localized, warm, infected joint
NOT acute chest syndrome as the presenting event — ACS requires a new pulmonary infiltrate plus fever, hypoxemia, tachypnea, or pleuritic pain, which she does not yet have (though it is the feared progression)
NOT a pure iron-deficiency or nutritional anemia — SCD is a structural hemoglobinopathy confirmed by HbS, not a microcytic deficiency state

Differential Diagnosis List

Sickle cell trait — ruled out by lifelong recurrent vaso-occlusive crises, which do not occur in trait
Acute chest syndrome — ruled out by absence of a new pulmonary infiltrate with fever/hypoxemia/tachypnea at presentation
Osteomyelitis/septic arthritis — ruled out by multifocal pain matching her typical crises rather than a single localized infected site
Other hemolytic anemias (hereditary spherocytosis, G6PD deficiency) — ruled out by identification of HbS on newborn screening/hemoglobin testing
Iron-deficiency anemia — ruled out by the structural hemoglobinopathy (HbS) confirmed on hemoglobin analysis

Key Distinguishing Test

The diagnosis is confirmed by hemoglobin analysis (hemoglobin electrophoresis, high-performance liquid chromatography, or isoelectric focusing) demonstrating a predominance of hemoglobin S with absent hemoglobin A in HbSS disease; molecular testing identifying biallelic HBB variants including at least one HbS (Glu6Val) allele is confirmatory.
There is no laboratory test that "rules in" a vaso-occlusive crisis itself—VOC is a clinical diagnosis based on patient report, and testing serves to exclude other causes of pain such as acute chest syndrome or infection.

Board Note

Suspect and confirm SCD with hemoglobin electrophoresis/HPLC; in the US most patients are identified by newborn screening, but confirm in anyone with unexplained normocytic anemia or severe atraumatic pain who lacks prior screening
VOC management is prompt analgesia: give parenteral opioids rapidly (first dose within ~1 hour of arrival) for severe pain, add NSAIDs, provide IV hydration and supplemental oxygen for hypoxia, and use incentive spirometry to prevent acute chest syndrome; do NOT transfuse for uncomplicated VOC
Acute chest syndrome (new infiltrate plus fever/hypoxemia/tachypnea/pleuritic pain) is a leading cause of death—treat with antibiotics (cephalosporin plus macrolide), oxygen, and transfusion (simple, escalating to exchange for severe/progressive disease)
Hydroxyurea is first-line disease-modifying therapy that raises fetal hemoglobin and reduces VOC and ACS frequency; monitor CBC for myelosuppression. Adjunctive/second-line options include L-glutamine and crizanlizumab, and hematopoietic stem cell transplant is the only established cure (note: voxelotor was withdrawn from the US market in 2024)
Preventive care reflects functional asplenia: childhood penicillin prophylaxis through at least age 5, pneumococcal and meningococcal vaccination, and daily folic acid; children need annual transcranial Doppler screening (ages 2–16) for stroke risk
Refer to hematology for chronic management, and watch for other complications—stroke, avascular necrosis, nephropathy, retinopathy, priapism, and gallstones
The materials below are grounded in current sources: the NEJM clinical practice reviews on renal colic and calcium stones, the 2023 ACR Appropriateness Criteria, the 2025 AUA surgical management guideline, and the ACP recurrence-prevention guideline with the 2026 systematic review.
─── PART 1 — DECODER SHEET ───

“Josephine’s Story”