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