Parathyroid hormone and magnesium: when “normal” is not always a good thing

This week, I’m at the 2009 national meeting of the American Society for Bone and Mineral Research in Denver, Colorado, learning about the most recent findings in bone research. I wanted to pass along an intriguing bit of information about magnesium deficiency and bone health.

If you’ve been following our work at the Center for Better Bones, you know that I often suggest clients be tested for both vitamin D and parathyroid hormone (PTH) levels. This is because low vitamin D levels can lead to high PTH, a condition that depletes bone.

Here’s how it works: when vitamin D is deficient, we cannot absorb enough calcium from our food to keep our blood calcium levels high enough to support our health. To achieve the necessary blood calcium level, the parathyroid gland releases PTH, which breaks down bone to release stored calcium for transfer into the blood. If this bone breakdown action continues over time, excessive bone loss can occur. In these cases, appropriate supplementation with vitamin D increases calcium absorption from food, which reduces the production of PTH. Normal PTH levels prevent excessive bone loss.

So when can a normal PTH level be a bad thing? When it’s caused by magnesium deficiency! People who are deficient in magnesium do not produce parathyroid normally even if their vitamin D levels are very low. I have seen such cases at the Center for Better Bones, where a person comes to me with low vitamin D status and yet has normal PTH.

In these cases, supplementing with vitamin D will help, but the magnesium deficiency needs to be addressed, too. Magnesium supports bone health on many levels, including stimulating the production of the bone-preserving hormone calcitonin and properly forming calcium crystals in bone. The best way to regulate production of PTH is by providing the body with the nutrients it needs to function well — especially vitamin D and magnesium. With ample nutrition, your body will naturally maintain healthy blood calcium levels while building strong bone — and your PTH will stay at a normal level for the right reasons!