Where is the parathyroid, and what does it do?
Parathyroid glands are located in the neck, on the thyroid gland. Most people have four pea-sized, oval-shaped parathyroid glands. Endocrine glands, such as the thyroid and parathyroid, secrete hormones, which are natural chemicals that regulate body functions. The job of the parathyroid is to secrete parathyroid hormone, which helps regulate how the body uses calcium.
Calcium is needed by cells in many parts of the body—the brain, heart, nerves, bones, and digestive system. Parathyroid hormone satisfies these needs by taking calcium from bone, where it is stored, and releasing it into the bloodstream.
“Communication” between the parathyroid and bloodstream help keep calcium at its normal level.
What is a parathyroid adenoma?
Sometimes, benign (noncancerous) growths called adenomas appear on one or more of a person’s parathyroid glands. The cause of most parathyroid adenomas is unknown. However, about 10 percent are thought to be hereditary. Radiation exposure of the head and neck also may increase the risk of adenomas (as in the people who were exposed to the atomic bomb in Hiroshima).
Adenomas cause the parathyroid gland to make more parathyroid hormone than the body needs, a condition called primary hyperparathyroidism. Too much parathyroid hormone upsets the body’s normal calcium balance, which increases the amount of calcium in the blood stream. A similar but less common condition, called secondary hyperparathyroidism, can occur in people with chronic kidney failure.
Women are twice as likely to develop pituitary adenomas as men, and often after menopause. Primary hyperparathyroidism may be caused by one adenoma, more than one adenoma (hyperplasia), or cancer (which is very rare).
How are parathyroid adenomas diagnosed?
Too much calcium in the blood (hypercalcemia) may not cause any symptoms at all or can cause a number of symptoms and medical conditions. These include:
- Depression or mental confusion
- Kidney stones
- Bone and joint pain
- Abdominal pain
- General aches and pains from no obvious cause
Parathyroid adenomas are usually discovered when a higher-than-normal calcium level shows up in a routine blood test, particularly in people without symptoms. Doctors then confirm the diagnosis of primary hyperparathyroidism with a test that shows parathyroid hormone levels in the blood are higher than normal.
Patients with parathyroid cancer have symptoms including:
- Bone pain
- Kidney disease
- Extremely high levels of parathyroid hormone in the blood
- Neck masses that can be felt with the hand
Sometimes the diagnosis of cancer is difficult to make, even after surgery. This is because parathyroid cancer cells look very similar to noncancerous adenoma cells. However, parathyroid cancer is so rare (less than 1 percent of all cases) that many head and neck surgeons (otolaryngologists) never see a patient with it.
How are parathyroid adenomas treated?
The most common treatment is to remove the enlarged gland (or glands). This surgery cures the problem 95 percent of the time.
Instead of surgery, some people with mild or no symptoms of primary hyperparathyroidism may decide to try hormone replacement therapy or medication options. These and other treatments do not reduce the extra amount parathyroid hormone in the blood. Instead, they fight back by preventing the loss of calcium from bone. Hormone replacement therapy or other treatments for this condition must be taken for the rest of your life.
A prescription medication called cinacalcet (Sensipar®) reduces both calcium and parathyroid hormone levels in people with chronic kidney failure (secondary hyperparathyroidism). However, its use in people with primary hyperparathyroidism is still being studied.
If I do not have symptoms, do I need surgery?
Surgery is the usual treatment for parathyroid adenoma, even for people who do not have obvious symptoms. Some people with only mild symptoms, such as feeling tired, forgetful, or depressed, may actually have another medical condition. When primary hyperparathyroidism is the cause, surgery can improve these symptoms and the person’s quality of life.
If you have hyperparathyroidism, a specific test (a bone density test) can show if the raised level of parathyroid hormone in your blood is causing serious calcium loss. Calcium loss can cause osteoporosis (thin bones) and increase the risk for fractures. X-rays of the kidney can show if you have kidney stones. The most common cause of kidney stones is too much calcium in your blood. These and other tests will help you and your doctor decide if surgery is appropriate for you.
If I decide to have a surgery, what should I expect?
A procedure called minimally invasive parathyroidectomy has become widely accepted for removing enlarged parathyroid glands on one side of the neck. The benefits of this surgery include smaller incisions, shorter operations, and fewer complications compared with traditional two-side (bilateral) open-neck surgeries.
Several weeks before surgery, the surgeon will order tests to locate your one or more overactive parathyroid gland(s). These tests may include:
- An ultrasound of the neck
- A scan that uses a drug called Tc-sestamibi
If the results of these tests do not locate the adenoma, other scans may be ordered including:
- Computed tomography (CT)
- Magnetic resonance imaging (MRI)
These presurgical imaging tests are quite accurate but not foolproof, and interpreting them requires skill and experience. If the results are still unclear, the surgeon might order more imaging tests to help pinpoint the location of a parathyroid adenoma.The surgeon plans the surgical approach based on how many adenomas are found and where they are located.
What happens during surgery to remove parathyroid nodules?
Minimally invasive surgery can be done if the patient has only one adenoma or two adenomas on the same side of the neck. Anesthesia may be local or general, depending on the surgeon’s judgment and the patient’s preference.
On the day of surgery, patients sometimes receive another low dose of 99m Tc-sestamibi to guide the surgeon’s incisions. An IV line is installed to measure the amount of parathyroid hormone in the patient’s blood before and after the surgeon removes the affected glands.
When the enlarged glands are highlighted by 99m Tc-sestamibi, the surgeon removes them through an incision of approximately 2 cm (less than 1 inch). Parathyroid hormone levels drop dramatically within 10 to 20 minutes after the surgeon successfully removes the glands with adenomas. If parathyroid hormone levels do not drop after the targeted glands are removed, the surgeon may switch to open-neck surgery to look for other adenomas.
The open-neck method is used instead of minimally invasive surgery for patients with adenomas on both sides of the neck or when preoperative imaging fails to locate one or more adenomas. The cure rates for open-neck and minimally invasive surgeries are similar.
What are the risks of having surgery?
All surgeries have risks. With parathyroid surgery, some patients experience:
- Hoarseness from paralysis of the voice box (from damage to the voice box nerve; permanent hoarseness [about 3.5 percent of patients]).
- Short-term or permanent low calcium levels in the blood (hypocalcemia).
To reduce these risks:
- A device can be used to monitor the nerve’s location during surgery.
- Hypocalcemia can be treated with calcium and vitamin D supplements or by leaving at least part of one parathyroid gland in the neck.
- Careful control of bleeding during surgery can reduce the risk of developing blood clots in the neck.