@southernlady Wow. So frustrating. Hope she listens to you.
I know you are a vitamin expert, but for other readers, below are some decent explanatory excerpts from a paper about vitamin D deficiency (in the context of thyroid disease) written by my son's endocrinologist, Theodore C. Friedman, M.D., Ph.D.:
Vitamin D
Vitamin D appears to have many effects besides being related to calcium and bone health. Some patients with low vitamin D levels have fatigue and bone pain, which is easily reversible with proper replacement of vitamin D. Vitamin D may protect against heart disease and some types of cancer. Vitamin D may also have some role in regulating the immune system and also reducing blood sugar levels in patients with diabetes. Proper vitamin D levels are needed to prevent osteoporosis. In conclusion, proper vitamin D levels are essential for one’s health, especially if you have thyroid problems
Vitamin D is really two different compounds, ergocalciferol (vitamin D2), found mainly in plants and cholecalciferol (vitamin D3), found mainly in animals. Both of these hormones are collectively referred to as vitamin D, and they can either be obtained in two ways. One is by exposure of the skin to the ultraviolet (UV) rays of sunlight or also from dietary intake.
When it comes to replacing Vitamin D, again we have to understand the difference between D2 (ergocalciferol) and D3 (cholecalciferol). Even though both forms of vitamin D are fat soluble, studies have shown that if you take D2, your levels rise, but then fall back to almost baseline in a few weeks. . In contrast, after D3, the levels stay high for a longer period of time. [NOTE: DS Patients need to take DRY forms of Vitamin D]
Different Forms of Vitamin D and How To Diagnose Vitamin D
Vitamin D itself is inactive and needs to get converted to the liver to 25-hydroxy vitamin D (25-OH vitamin D) and then in the kidney to 1, 25-hydroxy vitamin D. It is only the 1, 25- OH vitamin D which is biologically active. This form of vitamin D acts to allow for absorption of calcium from the intestinal tract. Therefore, patients with low vitamin D levels will have low calcium and in severe cases get rickets (in children) or osteomalacia (in adults) which is when the bone bows out and is poorly formed. In mild cases of vitamin D deficiency, osteoporosis occurs, but low calcium is rare.
The conversion from the 25-OH vitamin D to the 1, 25-OH vitamin D that occurs in the kidney is catalyzed by parathyroid hormone, also called PTH. Therefore, patients with very low vitamin D levels will have relatively high PTH levels often with low calcium levels... Additionally, the 25-OH vitamin D form which is the storage form and is much more abundant that the 1, 25-OH vitamin D form which although is active, is less abundant. Therefore, in states of vitamin D deficiency, low levels of 25-OH vitamin D are found, but the 1, 25-OH vitamin D levels are either normal or actually slightly high.
They are slightly high because the excess PTH that is stimulated by the low 25-OH vitamin D levels stimulates the conversion up to 25-OH vitamin D to the 1, 25-OH vitamin D. Thus,
patients that are vitamin D deficient usually have a low 25-OH vitamin D level, a high PTH level, a low normal calcium, and a normal or an elevated 1, 25- OH vitamin D level. However some patients may actually have a high normal calcium as the elevated PTH and 1, 25-OH vitamin D may cause increased calcium absorption from the GI track and reabsorption from the kidney. If 25-OH vitamin D levels were not measured, these patients might have been incorrectly diagnosed with mild hyperparathyroidism as they have a high normal calcium and a high PTH.
Dr. Friedman usually recommends measuring a 25-OH vitamin D to determine if a patient does have vitamin D deficiency... PTH and calcium can also be ordered. The 25-OH vitamin D assay has a normal range of approximately 20-60 ng/dL. However, this range may be too low for many patients.
In general, Dr. Friedman would recommend treatment of patients that have a 25-OH vitamin D of less than 30 ng/dL. Optimal levels of 25-OH Vitamin D for patients with thyroid diseases are probably 35-60 ng/dL.