A 3-year-old child is brought with bow legs (genu varum). X-ray shows widened, frayed, and cupped metaphyses of the distal radius, ulna, and knee. Serum calcium is low, phosphate is low, and alkaline phosphatase is markedly elevated. What is the diagnosis and the most important deficiency?

• A Hypophosphataemic rickets (X-linked) due to PHEX gene mutation
• B Renal osteodystrophy from secondary hyperparathyroidism
• C Scurvy due to vitamin C deficiency
• D Nutritional rickets due to vitamin D deficiency ✓

Explanation

Nutritional rickets from vitamin D deficiency is the most common metabolic bone disease in children in developing countries. The combination of low calcium, low phosphate, and high alkaline phosphatase with the classic metaphyseal cupping and fraying on X-ray is characteristic. Hypophosphataemic (X-linked) rickets shows normal or near-normal calcium with isolated hypophosphataemia due to renal phosphate wasting. Treatment is cholecalciferol supplementation.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.