Vitamin D deficiency presenting like hypophosphatemic osteomalacia

Osteomalacia is one of the most common osteometabolic diseases. It is typically caused by lack of vitamin D and is characterized by mineralization deficiency of the osteoid matrix in the cortical and trabecular bone. Indians are at particularly high risk for developing osteomalacia, because of their traditional clothing style and skin color. This condition is frequently misdiagnosed and it can present with bone pain and muscle weakness.

We report a case of osteomalacia with predominant hypophosphatemia.

A 41-year-old male presented with gradually progressive quadriparesis for past 6 months. Patient had low phosphorous (1.9 mg/dl) with calcium being 8.1 mg/dl and 25(OH)Vitamin D3 levels being 8.12 ng/ml. The patient was thought to have concomitant Vitamin D deficiency with possibility of tumor-induced osteomalacia. Further evaluation for the same was planned. However, patient was given a trial of Vitamin D supplementation before further investigations and had dramatic improvement in the form that muscle power improved gradually over next 6 weeks and was able to climb stairs after 2 months. Retrospectively patient gave a history of being at home for many months and there was no exposure to sunlight at all. The biochemical parameters normalized within 4 weeks of starting Vitamin D and serum alkaline phosphatase showed drastic reduction after 6 weeks. All his family members were screened and found to have Vitamin D deficiency including recent born twins having rachitic changes. This was a case of vitamin D deficiency, in 41-year-old male, which presented more like hypophosphatemic osteomalacia but characteristic history of lack of sunlight exposure and dramatic improvement with only vitamin D3 supplementation confirmed the diagnosis.

The presentation of vitamin D deficiency can be varied and high index of suspicion is important for treatment of this common but frequently misdiagnosed condition.