Anemia is not usually mentioned as a complication of vitamin D intoxication but has been described in patients with and without renal failure [1]. We report on a woman with vitamin D intoxication and anemia not caused by renal failure.

A 66-year-old woman was admitted to the emergency department with hypercalcemia diagnosed after 3 weeks of severe constitutional symptoms. Three years earlier, osteoporosis had been diagnosed and a rheumatologist had prescribed an extemporaneous formulation (200 IU of vitamin D and 1 g of calcium glucobionate twice daily), which was prepared by a pharmacist. Blood tests at admission showed a calcium level of 4.04 mmol/L, a hemoglobin concentration of 103 g/L, a urea concentration of 11.2 mmol/L, and a creatinine level of 146 µmol/L. After rehydration, the hemoglobin concentration decreased to 83 g/L. Anemia was nonspecific and nonregenerative, and results of additional tests (chest radiography, mammography, abdominal ultrasonography, bone scintigraphy, fibrogastroscopy, and colonoscopy) were normal. Parathyroid hormone was undetectable, and the plasma 25-hydroxyvitamin D level was 696 nmol/L (normal range, 15 to 125 nmol/L). Two months later, while the patient was receiving a milk-free diet, plasma 25-hydroxyvitamin D levels were high, serum calcium levels were normal, and anemia had resolved. Symptoms had begun roughly when a new bottle of pills with a vitamin D content of 200 µg (8000 IU) was started.

The association of hypercalcemia and anemia suggested a neoplastic origin; this idea was rejected when results of additional examinations became available. High vitamin D levels could directly affect hematopoietic cells [2] or act through high calcium levels, which inhibit erythroid colony formation in vitro [3] and erythropoietin production in vitro [4] and in vivo [5]. That calcium is more important than vitamin D itself is supported by the course of our patient, whose anemia subsided after normalization of calcium levels, despite high vitamin D levels.

In addition to the danger of extemporaneous formulations, which carry a higher risk for error than factory-made pills, anemia is another potential complication of vitamin D intoxication.