Avitaminosis D and Pathologic Fractures in a Young Woman

Abstract

A 29-year-old woman with Down syndrome was admitted with a fracture of the left femur and increased parathyroid hormone (PTH) levels. She had a 13-year history of muscle and bone pain, which caused difficulties in walking. Bone densimetry (dual-energy x-ray absorptiometry) showed low bone density (Z score [L2–L4]: −6.75 SD). Total and ionized calcium (Ca) and calciuresis were low (Ca, 1.69 mmol/L; Ca⁺⁺, 0.98 mmol/L; U Ca, 0.16 mmol/24 h), the alkaline phosphatase level was increased (236 U/L). Serum vitamin D level (25 [OH]D) was undetectable and parathyroid hormone was elevated (124.8 ng/L). Antiendomysial antibodies were positive. Celiac disease was diagnosed as the cause of malabsorption syndrome. A gluten-free diet and supplementation of vitamin D and calcium was started. Treatment resulted in weight gain, correction of anemia, normalization of calcium (Ca⁺⁺, 1.12 mmol/L), and 25 (OH)D levels (90.7 nmol/L). Vitamin D deficiency is more common than expected, and in cases of pathologic fracture and disturbance of the calcium metabolism, it should always be considered.