Decreased cutaneous vitamin D-synthesis in heavily melanized individuals: a rare cause for pathologic fractures of the hip.

Painful pathological fractures of the femoral neck and the subtrochanteric region of the femur are reported in two women originating from India. After exclusion of renal or intestinal causes, laboratory data on bone metabolism, scintigraphic and radiographic examinations were characteristic for the presence of secondary hyperparathyroidism. Based on vitamin deficiency and low calcium absorption, disturbed mineralization of bone and increased osteoclastic resorption have apparently led to osteomalacia and subsequent fracturing. Fracture localization necessitated surgical fixation in one patient; conservative treatment including protected weightbearing was effective in the other women. After supplementation of calcium and vitamin D3, levels of parathyroid hormone and scintigraphic alterations returned to normal in both patients. In these two cases, pathological fractures of the hip could be attributed to the presence of secondary hyperparathyroidism based on decreased cutaneous vitamin D synthesis......