ASK DR. H: Parathyroid problems can pull calcium from bones

Q: On a routine blood test, my serum calcium was high, and my doctor found that my parathyroid hormone level was elevated. For now, he’s just watching things. What is the implication of this? – K.W., Philadelphia

A: With all the talk these days about calcium and osteoporosis, you might think that a disorder that causes an increased level of calcium in the blood would be a good thing. But our bodies like balance. There’s a narrow range of calcium in the blood that’s needed for your muscle cells (including heart muscle) to contract and function properly, for clotting, for proper nerve function and for certain enzymes to activate normally. Too much calcium in the blood can cause confusion, constipation, kidney stones, nausea, excess urination, dehydration, muscle weakness and bone pain.

Parathyroid hormone, or PTH, is secreted by four pea-size glands in the neck, just behind the thyroid gland. A fall in blood calcium (or a rise in blood phosphorus) triggers PTH release. PTH increases the blood calcium level by reducing the amount of calcium our kidneys would normally excrete. Bones are a rich source of calcium, and PTH pulls calcium out of bones to maintain a proper blood calcium level.

If one or more parathyroid glands becomes enlarged and overactive, too much PTH is released. The calcium level in the blood will rise at the expense of bone mineral density. That can cause or accelerate osteoporosis.
If the calcium level is very high, those side effects I’ve described may appear. Fortunately, our bodies are forgiving and a mildly elevated calcium level won’t cause any obvious symptoms.

Mild hyperparathyroidism can be watched with periodic blood calcium checks and bone density studies. If signs or symptoms do appear, surgery to remove one or more overactive parathyroid glands is the only effective treatment. There aren’t any medications you can take to treat it, but watch your intake of dietary calcium.

Dr. Mitchell Hecht is a physician specializing in internal medicine. Send questions to him at: “Ask Dr. H,” P.O. Box 767787, Roswell, GA 30076. Because of the large volume of mail received, personal replies are not possible.

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