What is primary hyperparathyroidism?
Primary hyperparathyroidism is a common disease that occurs when one or more of the parathyroid glands become overactive. This leads to the overproduction of PTH, resulting in an abnormal elevation in serum calcium. In 85% of patients with primary hyperparathyroidism, the hypercalcemia is due to the benign enlargement of a single parathyroid gland, commonly referred to as a parathyroid adenoma. In 10%-15% of patients, primary hyperparathyroidism is caused by the
enlargement of all 4 parathyroid glands, a state called parathyroid hyperplasia. In addition, up to 5% of patients can have a double adenoma, or enlargement of 2 parathyroid glands. Secondary and tertiary hyperparathyroidism occurs in patients with kidney failure and is characterized by the enlargement of all 4 parathyroid glands (ie hyperplasia). This form of hyperparathyroidism differs from primary hyperparathyroidism and accordingly the treatment options are different (see secondary hyperparathyroidism section).
Primary hyperparathyroidism is a metabolic disorder in which one (or more) of the parathyroid glands produces too much parathyroid hormone, which can result in the loss of bone tissue. Primary hyperparathyroidism affects 28 out of 100,000 people in the US each year, and is more prevalent in women than in men. A function of the parathyroid hormone is to keep blood-calcium levels from going too low by releasing calcium from bones, conserving calcium that would be excreted by the kidneys, and increasing calcium absorption from food. When the hormone overacts, the result is a rise in the blood-calcium level. When one parathyroid gland becomes enlarged, the condition is called adenoma. When more than one becomes enlarged, the condition is called hyperplasia. Both of these conditions are benign (non-cancerous).
Symptoms of primary hyperparathyroidism include thirst, generalized weakness, joint and bone pain, osteoporosis, kidney stones, polyuria, and constipation. Other conditions that have been associated with hyperparathyroidism include depression, peptic ulcer disease, pancreatitis, and hypertension. In the severest form of the disease, which is rare today, patients may experience bone fractures due to the profound demineralization of bone, a process directly related to the overproduction of PTH. It is important to realize that many patients will be free of symptoms.
The diagnosis of primary hyperparathyroidism is made mostly on the basis of lab tests that show high levels of calcium and parathyroid hormone. About half the time, healthcare providers discover primary hyperparathyroidism inadvertently from a blood test drawn for other reasons. Once a provider suspects that a person has primary hyperparathyroidism, he or she will do a physical examination and will ask about symptoms of abdominal pain and constipation, depression, anxiety, memory loss, muscle weakness, and urinary problems. Urine is often collected to check for excess calcium. Imaging may be done to assess any bone loss. An ultrasound of the neck may be performed to determine if the parathyroid glands are enlarged. A computed tomography (CT) scan or magnetic resonance imaging (MRI) may be used to check for a tumor.
Surgery to remove one or more of the parathyroid glands is very successful in treating primary hyperparathyroidism. Because of this, surgery is usually recommended. In rare cases, if a patient does not show any signs or symptoms of the disease and has only mildly elevated calcium levels, the medical specialist may be willing to wait, observe carefully over time, and consider the nonsurgical approach of medications to prevent or treat complications and/or a further rise in calcium levels. Surgery is the treatment of choice; however, under certain circumstances, some medications for primary hyperparathyroidism may be considered. A specific class of diuretics, along with intravenous hydration, is used in the acute phase to lower levels of calcium in the blood while the person is awaiting surgery. Calcitonin may be used in injectable form. Estrogen may preserve bone mass and reduce calcium levels in postmenopausal women who are not able to undergo surgery. Bisphosphonates, such as tiludronate and alendronate, may be used after surgery.