Beyond Nutritional Deficiency: Persistent Rickets as a Manifestation of Vitamin D-Dependent Rickets Type II in a Toddler.

Vitamin D-dependent rickets type II (VDDR-II) is a rare hereditary disorder caused by mutations in the vitamin D receptor gene, resulting in resistance to active vitamin D and impaired calcium absorption. We report a 2-year and 6-month-old female toddler presenting with persistent rickets, delayed motor milestones, dental abnormalities, and recurrent hypocalcemia despite standard vitamin D and calcium supplementation. Initial assessment of nutritional rickets was reconsidered due to the development of pathological fractures and persistent biochemical abnormalities-including hypocalcemia, elevated parathyroid hormone, high bone-specific alkaline phosphatase, and markedly elevated 1,25-dihydroxyvitamin D3. The patient was managed with high-dose calcitriol and calcium, resulting in gradual clinical and biochemical improvement. This case emphasizes the importance of recognizing red flags for genetic rickets in children unresponsive to conventional therapy and demonstrates the utility of integrated clinical, radiographic, and biochemical evaluation for early diagnosis, particularly in resource-limited settings where molecular testing may not be available.