A Rare Case of Severe Vitamin D Deficiency Presenting as Diffuse Osteosclerosis

Maintaining calcium homeostasis is essential for various physiologic processes, with vitamin D playing a key role. Hyperparathyroidism typically causes fragility fractures and osteolytic lesions but rare cases can present with osteosclerosis. We report a 64-year-old woman with a history of gastric bypass presenting with back pain who was found to have diffuse osteosclerosis and hyperparathyroidism due to severe vitamin D deficiency. Nutritional supplementation led to symptom resolution. This case underscores the importance of considering bone-mineral pathology in patients with unexplained pain and highlights the need for close follow-up in postoperative care after bariatric surgery.