A 42-year-old woman with a 10-year history of hereditary spherocytosis presents with jaundice and splenomegaly. She has undergone splenectomy 5 years ago with good clinical response. Regarding the laboratory findings and management of hereditary spherocytosis, all of the following statements are correct EXCEPT:

Explanation

## Hereditary Spherocytosis: Diagnosis and Management ### Understanding the Correct Answer **Key Point:** **Splenectomy is NOT curative in hereditary spherocytosis.** While splenectomy provides dramatic clinical improvement (70–80% reduction in hemolysis), it does **NOT eliminate the hemolytic process**. The underlying RBC membrane defect persists; splenectomy merely removes the primary site of RBC destruction. **High-Yield:** After splenectomy, patients still have: - Persistent spherocytes on blood smear - Positive osmotic fragility test - Continued (though reduced) hemolysis - Risk of extravascular hemolysis in other tissues (liver, bone marrow) ### Pathophysiology: Why Splenectomy Is Not Curative ```mermaid flowchart TD A[Hereditary Spherocytosis]:::outcome --> B[RBC membrane protein defect]:::outcome B --> C[Loss of RBC deformability]:::action C --> D[Splenic trapping & phagocytosis]:::action D --> E[Hemolysis in spleen]:::urgent E --> F{Splenectomy?}:::decision F -->|Yes| G[Hemolysis reduced but NOT eliminated]:::action F -->|No| H[Progressive hemolysis]:::urgent G --> I[Extrasplenic hemolysis continues]:::outcome ``` ### Diagnostic Tests for Hereditary Spherocytosis | Test | Finding in HS | Clinical Use | |------|---------------|---------------| | **Blood smear** | Spherocytes (dense, no central pallor) | Initial screening | | **Osmotic fragility test** | **Increased** (RBCs lyse at higher osmotic pressure) | Confirms membrane defect | | **EMA/Flow cytometry** | Decreased EMA binding | Gold standard (replaces osmotic fragility) | | **Autohemolysis test** | Increased (>10% at 48 hrs) | Detects membrane defect | | **Genetic testing** | Mutations in spectrin, ankyrin, band 3, protein 4.2 | Confirmatory but not routine | **Clinical Pearl:** EMA (eosin-5-maleimide) binding test is now the **preferred diagnostic test** because it is more specific, sensitive, and objective than osmotic fragility, which can be affected by other conditions (e.g., AIHA). ### Why Other Options Are Correct 1. **Osmotic fragility is increased** — spherocytes have reduced surface-area-to-volume ratio and lyse at higher osmotic pressures than normal RBCs — correct. 2. **EMA binding test is the gold standard** — it has replaced osmotic fragility as the diagnostic test of choice — correct. 3. **Spherocytes result from membrane protein mutations** — defects in spectrin, ankyrin, band 3, or protein 4.2 cause loss of RBC deformability — correct. ### Clinical Outcomes After Splenectomy **Before splenectomy:** - Hemoglobin: 7–10 g/dL - Reticulocyte count: 10–20% - Bilirubin: elevated **After splenectomy:** - Hemoglobin: 10–13 g/dL (improvement but not normalization) - Reticulocyte count: 3–5% (reduced but still elevated) - Bilirubin: reduced but may remain mildly elevated - **Spherocytes persist on blood smear** - **Osmotic fragility remains abnormal**