Calcium

Blood calcium levels are controlled by parathyroid hormone and vitamin D, which maintain calcium levels by acting on kidneys, bones and intestines.  Small (pea-sized) parathyroid glands are located in the anterior neck next to the thyroid gland.  They produce parathyroid hormone (PTH), which in turn regulates calcium absorption from bone, kidney and intestines; these effects are also moderated by vitamin D.  Normally, as blood calcium levels decrease slightly, PTH increases to reabsorb more calcium; and conversely, as calcium levels increase, PTH secretion decreases.

Hyperparathyroidism is a condition where the parathyroid glands become enlarged and produce too much parathyroid hormone.  This subsequently causes hypercalcemia.  Prolonged hypercalcemia can impair kidney function, increase the risk for kidney stones and increase bone absorption – causing bone thinning (osteopenia/osteoporosis).

Most people with hyperparathyroidism are asymptomatic with small elevation in calcium levels.  Treatment of hyperparathyroidism is surgical removel of the enlarged parathyroid (which can often be done with a minimally invasive procedure).  Indications for recommending surgical removal are history of kidney stones, significant elevation of blood calcium and progressive bone thinning (osteoporosis).

Symptoms of significant hypercalcemia can include loss of appetite, nausea, constipation, increased thirst and urination, joint aches, fatigue, mild depression and difficulty concentrating.

Osteoporosis is significant bone thinning defined as a bone mineral density (BMD) more than 2.5 standard deviations below the mean for normal young women.  Osteopenia is a milder degree of bone thinning (between 1 and 2.5 standard deviations below the mean).  Adequate vitamin D and calcium intake are important in preventing progression of bone loss – particularly as we get older.

Medications to help decrease progression of bone loss (and actually sometimes increase bone density) include bisphosphonates (alendronate –Fosamax, riserdronate (Actonel) or ibandronate (boniva).  Estrogen and selective estrogen receptor modulators (avesta) are also used for treatment.

For more information, the following websites are available:
• The National Library of Medicine (http://www.nlm.nih.gov/hinfo.html)
• The Hormone Foundation (www.hormone.org)

  • Thyroid and parathyroid ultrasound are available in our office, for your convenience.

• Office location: 477 Congress Street (the Time & Temperature Building), 5th floor, Portland, Maine 04101

• Parking: Free parking is available in our garage, reached from Cumberland Ave.

• Telephone: 207-773-6463

• Fax: 207-828-4587

Thyroid and parathyroid ultrasound are available in our office, for your convenience.
David R. Hotelling, MD, FACE, is on the medical staff at Maine Medical Center and is a consulting staff member at Mercy Hospital. Dr. Hotelling is board-certified and completed a fellowship in endocrinology at Beth Israel Hospital in Boston, a Harvard affiliate.