Hyperparathyroidism

Primary hyperparathyroidism is a common condition and needs to be differentiated from other forms of hyperparathyroidism. 


What primary hyperparathyroidism means

The parathyroids are the glands in neck which monitor and control calcium levels via the parathyroid hormone (PTH).  If one or more parathyroid glands is abnormally secreting too much parathyroid hormone, there can be an abnormal increase in the level of calcium in the blood. "Primary" refers to the main problem being located primarily within the hormone secreting gland, "hyper" means too much, "parathyroid" refers to the parathyroid gland, and "ism" refers to a medical condition. There are also conditions of Secondary and Tertiary hyperparathyroidism, which are more rare.

What causes primary hyperparathyroidism

The cause of primary hyperparathyroidism is either a benign tumor of one parathyroid gland (very common), an overgrowth of all four parathyroid glands called hyperplasia (less common), or a malignant tumor of a parathyroid gland (extremely rare). More than 80% of cases are caused by a single parathyroid adenoma.  One hundred thousand new patients each year in the united states have a diagnosis of ths condition. An apparent increase in the incidence of primary hyperparathyroidism can be traced to the wide spread use of multi-channel analyzers in laboratories which has lead to earlier detection of the disease since 1970. 

Parathyroid adenoma


Parathyroid 4-gland hyperplasia




Diagnosis and localization of Abnormal Parathyroid Glands

The diagnosis of primary hyperparathyroidism is made by an endocrinologist who performs chemical testing to rule out other benign causes of hypercalcemia and finds inappropriately elevated parathyroid hormone. Imaging studies are NOT useful in diagnosing this condition and should only be done after the diagnosis has been confirmed chemically. Understanding the anatomy of the parathyroid glands is important in localizing which gland is abnormal. The most common studies for locating parathyroid adenomas have been 99 Tc MINI nuclear functional testing and ultrasonography. The endocrinologists at Houston Thyroid and Endocrine have ultrasound capabilities to visualize these tumors. CT and MRI Are also used for localization. These imaging studies are most helpful for the treating surgeon in planning the appropriate treatment.

Treatment

Once primary hyperparathyroidism is confirmed, then the treatment is primarily surgical. This surgery is called a parathyroidectomy and should be performed by a surgeon skilled in this type of operation. This operation removes the entire parathyroid tumor responsible for the high parathyroid hormone levels. There is a medication called cinacalet that is only approved to be used in patients that cannot undergo parathyroidectomy. The pill does not remove the tumor but reduces the parathyroid hormone production only. Treatment options need to be discussed with your endocrinologist.


Areas of uncertainty

At Houston thyroid and Endocrine we try to follow an evidenced based approach. There are no formal guidelines from professional societies for the management of primary hyperparathyroidism. Updated international guidelines for the management of asymptomatic primary hyperparathyroidism were published in 2009.  Long-term data from randomized trials need to be done to compare outcomes of parathyroidectomy versus nonsurgical management in patients with asymptomatic primary hyperparathyroidism. The frequency and significance of subtle cardiovascular and neurocognitive abnormalities in patients with asymptomatic primary hyperparathyroidism and the effects of parathyroidectomy on these manifestations warrant further study. Long term data to better define the incidence of fractures in primary hyperparathyroidism before and after successful parathyroid surgery are needed. We need to further understand the natural history of primary hyperparathyroidism with normal calcium levels. Also, more studies are needed in regards to prolonged use of cinacalcet. It is uncertain whether a T score of −2.5 is an appropriate bone-mineral-density criterion for surgery. What the correct level of 25-hydroxyvitamin D in patients with primary hyperparathyroidism remains uncertain.



References
Heath H III, et al. Primary hyperparathyroidism: incidence, morbidity, and potential economic impact in a community. NEJM 302:189-193. 1980

Primary Hyperparathyroidism Claudio Marcocci, M.D., and Filomena Cetani, M.D., Ph.D. N Engl J Med 2011; 365:2389-2397December 22, 2011

Bilezikian JPKhan AAPotts JT Jr. Guidelines for the management of asymptomatic primary hyperparathyroidism: summary statement from the Third International Workshop. J Clin Endocrinol Metab2009;94:335-339
Comments