Hyperparathyroidism is caused by factors that increase the production of parathyroid hormone.
The parathyroid glands maintain proper levels of both calcium and phosphorus in your body by turning the secretion of parathyroid hormone (PTH) off or on, much like a thermostat controls a heating system to maintain a constant air temperature. Vitamin D also is involved in regulating the amount of calcium in your blood.
Normally, this balancing act works well. When calcium levels in your blood fall too low, your parathyroid glands secrete enough PTH to restore the balance. PTH raises calcium levels by releasing calcium from your bones and increasing the amount of calcium absorbed from your small intestine.
When blood-calcium levels are too high, the parathyroid glands produce less PTH. But sometimes one or more of these glands produce too much hormone, leading to abnormally high levels of calcium (hypercalcemia) and low levels of phosphorus in your blood.
The mineral calcium is best known for its role in keeping your teeth and bones healthy. But calcium has other functions. It aids in the transmission of signals in nerve cells, and it's involved in muscle contraction. Phosphorus, another mineral, works in conjunction with calcium in these areas.
The disorder can generally be divided into two types based on the cause. Hyperparathyroidism may occur because of a problem with the parathyroid glands themselves (primary hyperparathyroidism) or because of another disease that affects the glands' function (secondary hyperparathyroidism).
Primary hyperparathyroidism occurs because of some problem with one or more of the four parathyroid glands:
- A noncancerous growth (adenoma) on a gland is the most common cause.
- Enlargement (hyperplasia) of two or more parathyroid glands accounts for most other cases.
- A cancerous (malignant) tumor is a rare cause of primary hyperparathyroidism.
Primary hyperparathyroidism usually occurs randomly, but some people inherit a gene that causes the disorder.
Secondary hyperparathyroidism is the result of another condition that lowers calcium levels. Therefore, your parathyroid glands overwork to compensate for the loss of calcium. Factors that may contribute to secondary hyperparathyroidism include:
May 28, 2014
- Severe calcium deficiency. Your body may not get enough calcium from your diet, often because your digestive system doesn't absorb the calcium from it.
Severe vitamin D deficiency. Vitamin D helps maintain appropriate levels of calcium in the blood, and it helps your digestive system absorb calcium from your food.
Your body produces vitamin D when your skin is exposed to sunlight, and you consume some vitamin D in food. If you don't get enough vitamin D, then calcium levels may drop.
- Chronic kidney failure. Your kidneys convert vitamin D into a form that your body can use. If your kidneys function poorly, usable vitamin D may decline and calcium levels drop. Chronic kidney failure is the most common cause of secondary hyperparathyroidism.
- Primary hyperparathyroidism. National Endocrine and Metabolic Diseases Information Service. http://endocrine.niddk.nih.gov/pubs/hyper/. Accessed Feb. 15, 2014.
- Ferri FF. Ferri's Clinical Advisor 2014: 5 Books in 1. Philadelphia, Pa.: Mosby Elsevier; 2014. https://www.clinicalkey.com. Accessed Feb. 15, 2014.
- El-Hajj Fuleihan G. Pathogenesis and etiology of primary hyperthyroidism. http://www.uptodate.com/home. Accessed Feb. 15, 2014.
- Papadakis MA, et al. Current Medical Diagnosis & Treatment 2014. 53rd ed. New York, N.Y.: The McGraw-Hill Companies; 2014. http://www.accessmedicine.com/resourceTOC.aspx?resourceID=1. Accessed Feb. 15, 2014.
- Bilezikian JP, et al. Guidelines for the management of asymptomatic primary hyperparathyroidism: Summary statement from the third international workshop. Journal of Clinical Endocrinology and Metabolism. 2009;94:335.
- Hormone replacement therapy. Micromedex 2.0 Healthcare Series. http://www.micromedexsolutions.com. Accessed Feb. 15, 2014.
- Vitamin D: Fact sheet for consumers. Office of Dietary Supplements. http://ods.od.nih.gov/factsheets/VitaminD-QuickFacts. Accessed Feb. 15, 2014.
- Calcium: Fact sheet for consumers. Office of Dietary Supplements. http://ods.od.nih.gov/factsheets/Calcium-QuickFacts. Accessed Feb. 15, 2014.
- Smoking and bone health. NIH Osteoporosis and Related Bone Diseases — National Resource Center. http://www.niams.nih.gov/Health_Info/Bone/Osteoporosis/Conditions_Behaviors/bone_smoking.asp. Accessed Feb. 15, 2014.
- Korkmaz HA, et al. Neonatal seizure as a manifestation of unrecognized maternal hyperparathyroidism. Journal of Clinical Research in Pediatric Endocrinology. 2013;5:206.
- Nippoldt TB (expert opinion). Mayo Clinic, Rochester, Minn. Feb. 28, 2014.
You Are ... The Campaign for Mayo Clinic
Mayo Clinic is a not-for-profit organization. Make a difference today.