Vitamin D-deficient osteomalacia due to excessive self-restrictions for atopic dermatitis

A 34-year-old Japanese woman presented with a 2-year history of generalised bone pain, muscle weakness and gait disturbance. The patient had been following a restricted diet (without fish or dairy products) and avoiding ultraviolet exposure for 8 years to manage her worsening atopic dermatitis. Physical examination revealed generalised bone tenderness and bilateral symmetric proximal muscle weakness. Vitamin D-deficient osteomalacia was diagnosed based on the laboratory examination findings, which indicated high serum alkaline phosphatase, high intact parathyroid hormone, and low 25-hydroxyvitamin D levels. Her symptoms improved after oral active vitamin D and calcium administration. To the best our knowledge, this case is the first report of vitamin D-deficient osteomalacia in an adult patient due to excessive dietary restriction for managing atopic dermatitis. We emphasise the importance of increasing awareness of vitamin D deficiency as a risk factor for the development of osteomalacia, and caution against excessive avoidance of sun exposure and dietary restriction.