Does “High” Vitamin D Cause High Calcium? Not in Olmstead County, MN

October 14, 2013 Leave your thoughts

We have “known” for years that 25-hydroxy Vitamin D levels over 50ng/ml are “too high” (hypervitaminosis D) and often cause high Calcium levels (hypercalcemia).   The Mayo Clinic designed a 10 year study to confirm that causal relationship.  It was presented at ASBMR.

NOF and others have called for higher Vitamin D supplementation and higher blood levels.  Mayo researchers expected to find many more cases of hypercalcemia related to many more cases of hypervitaminosis D.  The numbers of Vitamin D levels above 50ng/ml have doubled during the 10 years.  Levels above 80 and 100ng/ml have not increased.  The numbers of high calcium levels have not increased.  Those patients with the highest Vitamin D levels were not the patients with the highest Calcium levels.

The Mayo Clinic keeps track of patients in its home area (Olmstead County, MN).  This is a great way of tracking the health of a typical Midwestern population.  This study looked at “high” Vitamin D levels and related Calcium levels for 2002 through 2011.  Except for one patient taking her weekly Vitamin D dose daily, and more than twice the recommended Calcium dose daily, there were no cases of “Vitamin D toxicity”.

From this study, I draw two conclusions:                                                                   1.  Clearly the new recommendation of Vitamin D levels between 40 and 80ng/ml is not “too high”.                                                                                             2.  Maybe high Calcium levels are actually mild primary hyperparathyroidism, as some have suggested.

Jay Ginther, MD

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