A 16-year-old girl from Kerala with β-thalassemia intermedia (Hb 8.5 g/dL, transfusion-independent) presents with fatigue, bone pain, and growth retardation. Imaging shows severe osteoporosis with vertebral compression fractures. Serum ferritin is 1200 ng/mL (elevated despite no transfusions). Biochemical markers show low 25-OH vitamin D (18 ng/mL) and elevated alkaline phosphatase. What is the most appropriate next step in management?

Question

Accepted Answer

C. Start iron chelation therapy with deferasirox and vitamin D supplementation. ## Clinical Context

This is a case of **β-thalassemia intermedia** with:
- Transfusion-independent anemia (Hb 8.5 g/dL)
- Elevated ferritin (1200 ng/mL) from **ineffective erythropoiesis** and **extramedullary hematopoiesis**—not transfusion-related iron overload
- Severe osteoporosis with vertebral fractures
- Vitamin D deficiency (18 ng/mL)
- Growth retardation (endocrine dysfunction)

## Pathophysiology of Bone Disease in Thalassemia Intermedia

**Key Point:** Bone disease in thalassemia intermedia is **multifactorial**:

| Mechanism | Contribution |
|-----------|---------------|
| **Iron overload** | Suppresses osteoblast function, promotes osteoclast activity |
| **Ineffective erythropoiesis** | Marrow expansion → mechanical stress → trabecular loss |
| **Extramedullary hematopoiesis** | Splenomegaly, hepatomegaly; further iron deposition |
| **Vitamin D deficiency** | Impaired calcium absorption, secondary hyperparathyroidism |
| **Hypogonadism** | Growth hormone/sex hormone deficiency from iron deposition |
| **Chronic hemolysis** | Increased bone turnover |

## Management Approach

**High-Yield:** Thalassemia intermedia bone disease requires **dual therapy**:
1. **Iron chelation** (reduce iron-mediated osteoblast suppression)
2. **Vitamin D/calcium supplementation** (correct metabolic deficiency)

### Why Deferasirox?

- **Oral agent:** Better compliance in adolescents
- **Organ-protective:** Cardiac and hepatic iron removal
- **Bone-specific:** Improves osteoblast function and bone mineral density
- **Dose:** 20–30 mg/kg/day (adjusted for ferritin)

### Why Vitamin D Supplementation?

- Serum 25-OH vitamin D <20 ng/mL is **deficient**
- Supplementation: **Cholecalciferol 1000–2000 IU daily** or **ergocalciferol 50,000 IU weekly**
- Target: 25-OH vitamin D >30 ng/mL
- Improves calcium absorption, reduces secondary hyperparathyroidism, promotes osteoblast differentiation

## Why NOT Bisphosphonates First?

**Clinical Pearl:** Bisphosphonates (alendronate, zoledronic acid) are **second-line** in thalassemia bone disease. They:
- Do NOT address the underlying iron overload or vitamin D deficiency
- May impair bone remodeling if used without correcting metabolic defects
- Are reserved for **persistent osteoporosis despite iron chelation and vitamin D repletion**

Starting bisphosphonates without addressing iron and vitamin D is treating the symptom, not the disease.

## Monitoring After Initiation

- Ferritin level (monthly initially, then 3-monthly)
- Serum creatinine (deferasirox can cause renal dysfunction)
- 25-OH vitamin D (recheck at 8–12 weeks)
- Bone mineral density (DEXA scan at baseline and 1–2 years)
- Endocrine assessment (LH/FSH, testosterone, growth hormone)

[cite:Robbins 10e Ch 14]

Answer

A. Refer for splenectomy to reduce extramedullary hematopoiesis

Answer

B. Initiate bisphosphonate therapy immediately without further investigation

Answer

D. Perform bone marrow biopsy to exclude myelodysplasia

Explanation

Clinical Context

Pathophysiology of Bone Disease in Thalassemia Intermedia

Management Approach

Why Deferasirox?

Why Vitamin D Supplementation?

Why NOT Bisphosphonates First?

Monitoring After Initiation

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Mechanism	Contribution
Iron overload	Suppresses osteoblast function, promotes osteoclast activity
Ineffective erythropoiesis	Marrow expansion → mechanical stress → trabecular loss
Extramedullary hematopoiesis	Splenomegaly, hepatomegaly; further iron deposition
Vitamin D deficiency	Impaired calcium absorption, secondary hyperparathyroidism
Hypogonadism	Growth hormone/sex hormone deficiency from iron deposition
Chronic hemolysis	Increased bone turnover