The osteodystrophy of hypervitaminosis D: a metabolic study

Area of Science:

• Endocrinology
• Metabolic Bone Disease

Background:

• Vitamin D is crucial for calcium homeostasis and bone health.
• Excessive vitamin D intake can lead to toxicity, but its effects on bone mineralization are complex.

Observation:

• A patient on daily vitamin D2 for 10 years developed skeletal pain and hypercalcaemia.
• Radiographs revealed osteosclerosis with extensive calcification, while bone histomorphometry showed impaired mineralization.

Findings:

• Despite hypercalcaemia and elevated vitamin D metabolites, the patient exhibited defective bone mineralization and a negative calcium balance.
• Enhanced intestinal calcium absorption and increased urinary hydroxyproline excretion were noted.

Implications:

• This case highlights a rare form of vitamin D toxicity causing impaired bone mineralization.
• Cortisone therapy demonstrated efficacy in managing hypercalcaemia and improving calcium balance by modulating vitamin D metabolism.