A 2-year-old girl from coastal Tamil Nadu presents with her father reporting a 6-week history of progressive weakness, irritability, and recurrent respiratory infections. On examination, she has bleeding gums, poor wound healing, and petechial rash over her lower extremities. Her hemoglobin is 9.8 g/dL. Serum vitamin C level is 0.2 mg/dL (normal >0.6 mg/dL). Her diet consists mainly of boiled rice, lentils, and milk with no fresh fruits or vegetables. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Scurvy (Vitamin C Deficiency) ### Pathophysiology Vitamin C (ascorbic acid) is an essential cofactor for collagen synthesis and cross-linking. Deficiency leads to defective collagen in blood vessel walls, connective tissue, and bone matrix. In this toddler, prolonged dietary insufficiency (no fresh fruits or vegetables) has resulted in depleted vitamin C stores and clinical scurvy. ### Biochemical Role of Vitamin C 1. **Collagen synthesis:** Hydroxylation of proline and lysine residues (requires vitamin C as cofactor for prolyl and lysyl hydroxylase) 2. **Antioxidant function:** Protects against oxidative stress 3. **Iron absorption:** Enhances absorption of non-heme iron 4. **Immune function:** Supports neutrophil and T-cell function **Key Point:** Vitamin C deficiency impairs collagen cross-linking, leading to fragile blood vessels, poor wound healing, and bleeding manifestations. ### Clinical Features of Scurvy | Feature | Mechanism | Timing | |---------|-----------|--------| | Bleeding gums, petechiae | Fragile capillaries from defective collagen | 1–3 months | | Poor wound healing | Defective collagen synthesis | 2–4 weeks | | Weakness, irritability | Anemia + systemic inflammation | Progressive | | Recurrent infections | Impaired neutrophil and T-cell function | Variable | | Bone pain (subperiosteal hemorrhage) | Bleeding into bone matrix | Later stage | | Follicular hyperkeratosis | Keratinous plugging of hair follicles | Characteristic | **Clinical Pearl:** The combination of bleeding gums + petechiae + poor wound healing in a toddler with a diet devoid of fresh fruits/vegetables is virtually diagnostic of scurvy. The low serum vitamin C (<0.3 mg/dL) confirms the diagnosis. ### Laboratory Findings - **Serum ascorbic acid:** <0.2 mg/dL (normal >0.6 mg/dL) — diagnostic - **Hemoglobin:** May be low due to bleeding and impaired iron absorption - **Bleeding time:** Normal (platelet function intact) - **Prothrombin time:** Normal (vitamin K-dependent factors intact) - **X-ray findings:** Scorbutic rosary (subperiosteal hemorrhage), Wimberger's sclerotic ring (dense ring around epiphyses) **High-Yield:** Scurvy is a clinical diagnosis supported by low serum vitamin C and response to supplementation. Bleeding time and PT/INR are normal, distinguishing it from coagulation disorders. ### Management 1. **Vitamin C supplementation:** 100–200 mg/day orally (rapid clinical response within 1–2 weeks) 2. **Dietary counseling:** Introduce citrus fruits, tomatoes, leafy greens, amla (Indian gooseberry) 3. **Iron supplementation:** If anemia is present (vitamin C enhances iron absorption) 4. **Expected response:** Gum bleeding stops within days, petechiae fade within 1–2 weeks, strength returns within 2–3 weeks **Mnemonic:** **SCURVY** = **S**wollen gums, **C**annot heal wounds, **U**nder-skin bleeding (petechiae), **R**ecurrent infections, **V**itamin C deficiency, **Y**earning for fresh fruits [cite:Park 26e Ch 10; Harrison 21e Ch 100]