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Yet Another Reason to Take Vitamin D

April 4, 2000 (Atlanta) -- People with the common metabolic disorder hyperparathyroidism who consume plenty of vitamin D seem to be less affected by the disease than those who don't, a new study has found.

Hyperparathyroidism is caused by a malfunction of the parathyroid glands in the neck, which regulate calcium in the blood. The disease most often strikes women, particularly older women. It can cause fatigue, disorientation, and depression, and can also lead to bone loss, kidney stones, and even coma.

The study, published in the Journal of Clinical Endocrinology and Metabolism, found an inverse relationship between the severity of the disease and patients' intake of vitamin D through diet and supplements. Such a link has long been suspected, but hadn't been shown until now, and the finding may affect the way some physicians treat the disease.

"The finding is, there was a relationship between vitamin D nutrition and the severity of the disease; in other words, the lower the level [of vitamin D], the larger the tumor size and more effect it will have on the body," study author D. Sudhaker Rao, MD, tells WebMD.

"Historically in this country, hyperparathyroidism [patients] frequently had bone disease, but currently you don't see that much. Part of this might be related to the fact that vitamin D was added to milk in the 1940s," says Rao, who is division head of Bone and Mineral Metabolism at the Henry Ford Health System in Detroit.

"In contrast, in parts of the world where vitamin D nutrition is poor -- for example, in parts of Asia -- hyperparathyroidism is frequently associated with bone disease. In fact, 90% of patients in that part of world have bone disease and larger tumors."

Anne E. de Papp, MD, who reviewed the study for WebMD, says there may be another reason U.S. doctors now tend to see less severe hyperparathyroidism.

"There is certainly more awareness among women, particularly postmenopausal women -- that is who this disease mostly affects. They know to take calcium supplements and vitamin D," says de Papp, a clinical assistant professor of medicine at Thomas Jefferson University in Philadelphia.

Rao and colleagues studied nearly 150 patients with the primary form of hyperparathyroidism who were cured by the removal of a single adenoma -- a parathyroid gland that has developed into a benign tumor -- between 1992 and 1997.

The researchers found a significant inverse relationship between the weights of the tumors and the amount of vitamin D in the blood. They also found a connection between vitamin D levels and levels of parathyroid hormone (PTH), which is overproduced by the glands of people with hyperparathyroidism.

"Those patients with the lowest vitamin D levels had ... the largest tumors, the highest parathyroid hormone [PTH] levels, and potentially they would be the ones most likely to have the worst bone disease because the PTH causes bone resorption and can lead to osteoporosis," says de Papp.