The commonality of parathyroid tumors is often confusing because the term encompasses both highly frequent benign growths and extremely rare cancers. These growths cause primary hyperparathyroidism (PHPT), a condition where one or more of the four tiny glands in the neck become overactive. The primary issue is not the tumor itself but the resulting hormonal imbalance, which disrupts the body’s entire calcium regulation system.
Understanding Parathyroid Tumors
The parathyroid glands normally regulate calcium by releasing parathyroid hormone (PTH) to maintain levels within a narrow range. A parathyroid tumor is an abnormal proliferation of cells that ignores these signals, leading to an excessive and unregulated release of PTH.
The vast majority of these growths, estimated at 80 to 85% of cases, are non-cancerous tumors called parathyroid adenomas, which typically affect only one gland. Parathyroid carcinoma, the malignant form, is exceptionally rare, accounting for less than 1% of all primary hyperparathyroidism cases. Therefore, discussions about the commonality of parathyroid tumors focus almost entirely on the frequency of benign adenomas and the resulting PHPT.
Incidence and Prevalence Statistics
Primary hyperparathyroidism is recognized as a common endocrine disorder, often cited as the third most frequent after diabetes and thyroid disease. Recent age-adjusted prevalence rates in the United States suggest it affects approximately 233 per 100,000 women and 85 per 100,000 men. Incidence, or the rate of new cases per year, has been reported to range widely, with some studies indicating 4 to 6 new cases per 10,000 person-years.
The prevalence of PHPT has significantly increased over the past several decades. This rise is attributed to the widespread use of routine blood panels that automatically include calcium measurements, not a change in the disease itself. Consequently, most cases are now discovered incidentally in people who have few or no symptoms.
The Clinical Impact of Hypercalcemia
The commonality of these tumors matters because the resulting high calcium level in the blood, known as hypercalcemia, has a widespread impact on the body. Chronic exposure to excessive PTH causes calcium to leach from the bones, leading to skeletal issues like osteopenia and osteoporosis, which increases the risk of fractures.
In the renal system, the excess calcium must be filtered, often resulting in painful kidney stones and impaired kidney function. Hypercalcemia also affects the nervous and gastrointestinal systems, manifesting as persistent fatigue, depression, difficulty concentrating, and chronic constipation. Untreated, the condition can contribute to cardiovascular issues, including hypertension and the calcification of blood vessels.
Key Risk Factors and Detection
Certain factors increase an individual’s susceptibility to developing parathyroid tumors. The risk increases significantly with age, and the condition is most frequently diagnosed in individuals over 60. Women are two to three times more likely to develop PHPT than men, with the highest rates seen in post-menopausal women.
Known environmental and genetic factors also contribute to risk, including a history of therapeutic radiation exposure to the head or neck area. A small percentage of cases are linked to inherited genetic syndromes, such as Multiple Endocrine Neoplasia Type 1 (MEN1). Detection today primarily relies on the incidental finding of an elevated blood calcium level during routine metabolic panel testing.