http://chriskresser.com/the-role-of-...roid-disorders skriver langt og flott om D3 og stoffskifteproblemer.

“Okay, fine,” you say. “I’ll just get my vitamin D measured, and if it’s low, I’ll take supplements.”
If only it were that simple. We now know that certain people with normal serum levels of vitamin D still suffer from deficiency symptoms. How is this possible?

In order for circulating vitamin D to perform its functions, it must first activate the vitamin D receptor (VDR). The problem is that many people with autoimmune disease have a genetic polymorphism that affects the expression and activation of the VDR and thus reduces the biologic activity of vitamin D. Studies have shown that a significant number of patients with autoimmune Hashimoto’s disease have VDR polymorphisms.

In plain English, here’s what this means: if you have low thyroid function, you might be experiencing vitamin D deficiency even if your blood levels of vitamin D are normal. It also means that, if you have a VDR polymorphism, it’s likely you’ll need to have higher than normal blood levels of vitamin D to avoid the effects of vitamin D deficiency.