This article was published by the National Institutes of Health Osteoporosis and Related Bone Diseases~National Resource Center
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What is Primary Hyperparathyroidism?
Primary hyperparathyroidism is a hormonal problem due to one or more parathyroid glands producing too much parathyroid hormone. Parathyroid glands, four small glands located in the neck near the thyroid gland, keep blood calcium from falling below normal. Rarely, there are more than four of these glands, and they may be in other parts of the neck or in the chest. In 80 to 85 percent of patients with primary hyperparathyroidism, a single gland is affected In 15 to 20 percent of patients, two or more glands are affected. The affected gland(s) enlarge and produce too much parathyroid hormone. As a result, blood calcium becomes high, bones may lose calcium, and kidneys may excrete too much calcium.
Who is Affected?
In the United States, 28 out of 100,000 people develop primary hyperparathyroidism each year. Women outnumber men 3 to 1, and frequency increases with age. In most cases, the cause is unknown. Previous exposure to radiation in the facial or neck area and certain medications (including thiazide diuretics and lithium) may cause primary hyperparathyroidism. In some families, the disease may be inherited. Parathyroid cancer is an extremely rare cause of primary hyperparathyroidism.
Even in patients who have no symptoms, primary hyperparathyroidism can cause bones to become less dense and can also lead to kidney stones. When the blood calcium exceeds the routine elevations seen in primary hyperparathyroidism, symptoms can include:
- loss of appetite
- frequent urination
- muscle weakness
- joint pain
When the blood calcium becomes very high, more severe symptoms include:
- abdominal pain
- memory loss
Primary hyperparathyroidism is usually diagnosed through a routine blood test. Once suspected, the following additional tests are done:
- Blood test – For calcium, phosphorus, alkaline phosphatase, 25-hydroxyvitamin D, 1,25-dihydroxy-vitamin D, and parathyroid hormone to determine the activity of the disease.
- Urine test – For calcium, kidney function, and "bone markers" that indicate whether a patient is likely to be losing bone calcium.
- Urinalyses and kidney X-rays – In some cases these are needed to check on kidney stone formation.
- Bone density test – This test is the only way to measure bone density.
Types of physicians
Physicians who treat primary hyperparathyroidism include endocrinologists (internists who specialize in hormonal and metabolic disorders) and surgeons who specialize in endocrine surgery. Upon request, The Paget Foundation can supply a list of medical specialists.
At present, the only known cure for primary hyperparathyroidism is surgical removal of the affected gland(s). Experts have developed guidelines to help determine who should have surgery. The decision requires careful evaluation and individual assessment.
An experienced surgeon often does not require imaging tests to locate the affected gland(s). However, if needed, several non-invasive tests may be used including ultrasound, computerized tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and the Sestamibi scan. Sestamibi is a chemical that localizes in the abnormal parathyroid gland. The Sestamibi scan, especially performed with computerized tomography (SPECT), is the most specific test. In some cases, an invasive test, such as arteriography or blood sampling in the neck, may be required prior to surgery.
Recently three surgical techniques termed "minimally invasive parathyroidectomy" have been developed. These new techniques are generally performed in select medical centers by experienced parathyroid surgeons. The Sestamibi scan is used for these procedures.
These techniques include:
- Removal of a single gland using local anesthesia. During the operation, the blood parathyroid hormone level is measured. After the gland is removed, the hormone level is tested again. A normal hormone level indicates a successful operation.
- Use of a detector to measure abnormal activity before and after surgery. Following a Sestamibi scan, the detector is passed over the area of the operation to further identify the overactive gland(s) and measure abnormal activity. The detector is used again following removal of the gland(s) to ensure that all abnormal activity has been eliminated.
- Removal of the affected gland by an endoscope, an instrument used for examination of a body cavity.
Parathyroid surgery can be performed under general, regional, or local anesthesia. Local anesthesia does not prevent the surgeon from identifying all parathyroid glands. The operation is successful in over 95 percent of cases when performed by an experienced parathyroid surgeon. Therefore, an experienced parathyroid surgeon is strongly recommended. Serious complications are uncommon. Surgery usually leaves a thin, faint horizontal scar about three inches long in the lower neck.
Parathyroid autotransplantation is reserved for patients in whom all four parathyroid glands are affected or who need repeat surgery resulting in the removal of all or excessive amounts of parathyroid tissue. This can result in hypoparathyroidism, or the production of too little parathyroid hormone. To prevent this from occurring, parathyroid autotransplantation is performed. All parathyroid tissue in the neck is removed, and a small amount is transplanted to the forearm where it can remain and perform its function of producing parathyroid hormone for the body. If the parathyroid tissue in the forearm enlarges over time, it can be readily reduced by a simple office procedure. Parathyroid autotransplantation should be performed only in medical centers and by surgeons with experience in this procedure.
Alternatives to surgery
- Monitoring – Asymptomatic patients are not always recommended for surgery. If surgery is not to be performed, these patients should be monitored regularly with blood testing for calcium every 6 months. Every year these patients should undergo a urinary calcium test and a bone density test. Most patients do not get worse over years of follow-up care.
- Estrogen therapy – This treatment may reduce some effects of the disease in postmenopausal women, but will not directly control glandular overactivity.
- Bisphosphonates – These drugs, used to treat osteoporosis and Paget's disease of bone, are currently being evaluated in primary hyperparathyroidism.
- Experimental drugs – Some drugs that control serum calcium are being investigated. These drugs are not yet approved or available.
Removing the affected gland(s) cures the condition. Kidney stones do not tend to recur. In patients with reduced bone density, major improvements are seen over 1 to 4 years. However, nonspecific symptoms such as weakness and easy fatigability are not always eliminated.
Suggestions for patients
Patients should drink enough fluid to avoid dehydration, which leads to an increase in blood calcium. To avoid worsening calcium levels, patients should get regular exercise and avoid immobilization. A diet including approximately 1200 mg of calcium is recommended. Avoiding calcium-containing foods could further stimulate the parathyroid glands.
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