Caution needed with vitamin D in certain conditions

The American Endocrine Society’s guidelines state: “Vitamin D supplementation should not be a major concern except in certain populations who may be more sensitive to it.” Such populations are those who have chronic granuloma-forming disorders, including the following conditions:

• sarcoidosis
• tuberculosis
• chronic fungal infections
• lymphoma

In these conditions, cells of the immune system called macrophages become activated and sometimes produce vitamin D₃ in excessive amounts. As a result, people with these conditions can absorb higher-than-normal amounts of calcium from their intestine. Also, having these inflammatory conditions often triggers the release of calcium from the skeleton into the blood. This leads to higher-than-normal levels of calcium in the blood and in the urine as the body tries to flush out this mineral. The Endocrine Society states that vitamin D and calcium levels in patients with these disorders should be carefully monitored. Excess calcium in the blood and urine of these patients tends to occur when the amount of vitamin D in the blood is greater than 75 nmol/litre.

—Sean R. Hosein

REFERENCES:

1. Holick MF, Binkley NC, Hike A, et al. Evaluation, treatment and prevention of vitamin D deficiency: an Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology and Metabolism. 2011 Jul;96(7):1911-30.
2. Sage RJ, Rao DS, Burke RR, et al. Preventing vitamin D toxicity in patients with sarcoidosis. Journal of the American Academy of Dermatology. 2011 Apr;64(4):795-6.
3. Burke RR, Rybicki BA, Rao DS. Calcium and vitamin D in sarcoidosis: how to assess and manage. Seminars in Respiratory and Critical Care Medicine. 2010 Aug;31(4):474-84.