Primary hyperparathyroidism is a disorder of the four pea-sized parathyroid glands located in the neck. The condition arises when one or more of these glands become overactive, producing an excess of parathyroid hormone (PTH). The function of PTH is to regulate calcium levels by signaling bones to release calcium, helping the intestines absorb it from food, and prompting the kidneys to retain it.
When the glands produce too much PTH, blood calcium levels rise above the normal range, a state known as hypercalcemia. This elevation of calcium is the underlying source of the health issues associated with the condition. Many cases are identified early through routine blood tests, often before significant symptoms develop.
Causes of Primary Hyperparathyroidism
The most frequent cause of primary hyperparathyroidism is a noncancerous growth, called an adenoma, on one of the parathyroid glands. In other instances, the condition results from the enlargement of two or more parathyroid glands, a condition known as hyperplasia. The specific trigger for this enlargement is often unknown.
A very small fraction of cases are caused by a cancerous tumor on a parathyroid gland. Certain factors increase a person’s risk of developing the condition, which is more common in women, particularly after menopause, and in individuals over 50. Some inherited genetic disorders can also predispose an individual to primary hyperparathyroidism, sometimes involving tumors in other parts of the body.
Signs and Symptoms
Many individuals with primary hyperparathyroidism experience no symptoms, and the condition is discovered incidentally during blood tests. When symptoms do manifest, they are related to the effects of high calcium levels on various body systems. The range of symptoms can be remembered by the phrase “bones, stones, abdominal groans, and psychic moans,” which categorizes the main areas affected.
The skeletal system is impacted because excess PTH causes calcium to be pulled from the bones. This process can lead to a thinning of the bones, known as osteoporosis, making them more susceptible to fractures. Individuals might experience bone and joint pain, particularly in the hands, arms, legs, and feet.
The kidneys are also affected by high blood calcium levels. As the kidneys work to filter the blood, excess calcium can lead to the formation of hard deposits called kidney stones, which can cause pain in the abdomen or side. Other related symptoms include increased thirst and frequent urination as the body attempts to eliminate the excess calcium.
Digestive, or “abdominal groan,” symptoms can also occur. These may include constipation, nausea, vomiting, loss of appetite, and general abdominal pain.
Finally, the condition can produce psychological or neurological effects, sometimes referred to as “psychic moans.” Patients may report feeling persistent fatigue, lethargy, and muscle weakness. Some people also experience changes in mood, such as depression, as well as cognitive difficulties like memory loss or trouble concentrating.
Diagnostic Process
The diagnosis of primary hyperparathyroidism begins with blood tests that measure the levels of calcium and parathyroid hormone (PTH). A simultaneous finding of high calcium and high PTH in the blood is the primary marker for the condition. Normally, high blood calcium would cause PTH levels to be low, so an elevated PTH level confirms the parathyroid glands are inappropriately overactive.
Once high calcium and PTH are confirmed, a physician may order additional tests to evaluate the condition’s impact on the body. A 24-hour urine collection test is often used to measure the amount of calcium being excreted, which helps assess kidney function and the risk of developing kidney stones.
To assess bone health, a bone mineral density scan, known as a DEXA or DXA scan, is performed. This imaging test measures the density of bones in areas like the hip and spine to determine if bone loss has occurred.
Imaging tests are also used, not for diagnosis, but to locate the overactive gland or glands before treatment. An ultrasound of the neck is a common first step. A more specialized test called a sestamibi scan may also be used, which involves injecting a radioactive tracer that is absorbed by the overactive gland, making it visible on the scan.
Treatment Approaches
The most definitive treatment for primary hyperparathyroidism is a surgical procedure called a parathyroidectomy. This surgery involves the removal of the overactive gland or glands and provides a cure in the vast majority of cases. Surgery is recommended for patients who have symptoms, complications like kidney stones or significant bone loss, or are under the age of 50.
For individuals who are not candidates for surgery or who have a very mild, asymptomatic form of the disease, a strategy of active surveillance may be chosen. This approach involves a doctor periodically checking blood calcium levels, kidney function, and bone density to track the disease’s progression.
Medication is another treatment option for those who cannot undergo surgery or to manage severe hypercalcemia. One class of drugs, called calcimimetics, works by mimicking calcium in the blood, which tricks the parathyroid glands into producing less PTH. While this can lower calcium levels, it does not improve bone density. For patients with bone loss, another class of drugs called bisphosphonates may be prescribed to help protect and increase bone density.