Wednesday, May 12, 2010

The dangers of high dose vitamin D

Back in November I posted on a patient who had a dramatic improvement in her PTH following correction of her vitamin D deficiency. One of the comments was:

Anonymous said...
Why wait one entire year to correct the Deficiency. I would have treated with 100,000 units po qd for 5-10 days.

I responded...
Regarding the time to treat the patient. This patient had almost no appreciable renal disease outside of the SHPTH. I was not going to schedule frequent visits to monitor therapy I just put them on a safe and familiar vitamin D dose and followed up every six months. I don't think I harmed the patient with slow therapy. The one time I had a patient on 50,000 units daily (resident error) they were readmitted within 2 weeks with hypercalcemia.
What I was really thinking was I never considered a more aggressive replacement regimen. This weeks JAMA provides some insight in the potential dangers of rapid and high dose vitamin D replacement. It is a randomized, placebo-controlled study looking at whether giving half a million units of oral cholecalciferol once a year can reduce the number of falls and fractures. Surprising, at least to me, was the higher risk of falls in the experimental group.

The investigators did a post-hoc analysis on the timing of the falls and found they were more likely to occur right after the vitamin D and the risk attenuated as more time passed after the dose. Thus implicating the drug itself as the cause.

The accompanying editorial is quite good and provides references for additional studies that also point to higher fall risk with high doses of vitamin D.
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