Low levels of vitamin D can suppress calcium levels and therefore make the calcium test look normal even when a person has hyperparathyroidism. Low levels of vitamin D can damage the parathyroid in the first place and then suppress the results of this test.

Secondary hyperparathyroidism  occurs when another medical condition causes the parathyroid glands to produce too much PTH in response to chronically low levels of circulating calcium. Kidney failure, malabsorption problems and rickets, a disease caused by severe vitamin D deficiency, are the main causes of this type of hyperparathyroidism.

Secondary hyperparathyroidism, hip bone loss and risk of hip fracture are all reduced by combined calcium and vitamin D3  according to the Decalyos II study.

Vitamin D in Patients with PRIMARY Hyperparathyroidism

Measuring Vitamin D levels in patients with hyperparathyroidism began in the mid-1990's. For the past several years, we have measured it in most patients, and beginning in 2006 we began measuring Vitamin D in every patient with PRIMARY hyperparathyroidism. Here is what we found in our recently published article on 1587 patients with primary hyperparathyroidism:

vitamin D levelds parathyroid67% of all patients with primary hyperparathyroidism will have LOW Vitamin D-25 Levels! This is 1039 patients out of 1587 in our study. 594 patients (38%) had levels below 20 ng/ml with an average Vitamin D level of 14.6.

33% of all patients with primary hyperparathyroidism will have NORMAL Vitamin D-25 Levels (above 30). Their average Vitamin D level was 35.3 ng/ml.

0 % of all patients with primary hyperparathyroidism will have HIGH Vitamin D-25 Levels (we've only seen it a dozen or so times when examining Vitamin-D levels in over 8000 patients with parathyroid tumors).

As the calcium level increases, the level of Vitamin D-25 decreases. The following graph shows this nicely. When we look at 1587 patients with a parathyroid tumor (we know it because we removed the tumor and gave the patient a picture of it), we see that those with higher calcium levels tend to have lower Vitamin D levels. As you will read below, this is because the body is trying to protect itself from the high calcium, and it is converting the active form of Vitamin D (Vit-D-25) into the inactive form Vit-D-1-25. This serves to decrease the amount of calcium absorbed from our diet, to keep the calcium from getting even higher. Read that again... the body is protecting itself from the high calcium. It does this by converting the active Vitamin D-25 into the inactive Vitamin D-1-25 so we don't absorb calcium in our diet.



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