The parathyroid glands are four small glands located in the neck near the thyroid gland. These glands control the calcium and phosphorous levels in the blood through the production of parathyroid hormone. Normally, the parathyroid hormone is produced when the calcium levels in the blood drops too low.
When this hormone is produced, the bones release calcium, the intestines absorb more calcium, and the kidneys decrease the amount of calcium excreted in the urine, thereby increasing the calcium level in the blood. When the intestines and kidneys do not take enough calcium from the bloodstream, and the bones are depleted of calcium, the calcium level in the blood is too high.
In most patients with parathyroid problems, there is an enlargement of a single parathyroid gland that produces too much parathyroid hormone. These abnormal glands also lose their ability to sense the higher levels of calcium in the blood and turn off the production of hormone when this occurs. Over time, the increasing levels of calcium in the body can cause symptoms typically related to hyperparathyroidism:
There are three main forms of hyperparathyroidism, which are defined by the reason why the glands are diseased:
Primary hyperparathyroidism is the most common form of hyperparathyroidism—approximately 90 percent of patients with hyperparathyroidism have primary hyperparathyroidism—and typically affects otherwise healthy individuals. This disease is usually caused by a benign growth and overproduction of parathyroid hormone by one of the four parathyroid glands.
Occasionally, in around 10 to 20 percent of patients, more than one gland that is producing too much parathyroid hormone. These glands begin to grow and produce too much hormone likely because of a genetic mutation or defect in the cells that produce parathyroid hormone and regulate the level of calcium in the blood. The risk of parathyroid cancer is exceedingly small, and most patients with primary hyperparathyroidism can be treated successfully with a single surgery.
Secondary hyperparathyroidism can have several causes, all of which are caused by an abnormality in the body's regulation of calcium. Most patients with this form of hyperparathyroidism also have chronic kidney failure. Kidney failure causes an abnormality in calcium regulation because of the body's inability to regulate calcium and phosphorus excretion in the urine.
Patients with secondary hyperparathyroidism are often initially treated with medications to prevent buildup of phosphorus in the body and to inhibit parathyroid hormone with a medication called cincalcet. These medications are unable to control the effects of hyperparathyroidism, surgical removal of the majority of the abnormal parathyroid glands can be an effective treatment. This operation often requires a longer hospital stay, because of the chronic nature of the disease and the need to closely monitor calcium levels following the procedure.
Tertiary hyperparathyroidism occurs in patients that have undergone kidney transplantation for kidney failure. These patients have developed secondary hyperparathyroidism prior to receiving the kidney transplant. Typically, hyperparathyroidism will resolve over the first year following kidney transplantation because the new kidney can adequately control calcium and phosphorus excretion in the urine, and over time the parathyroid glands to begin to function normally again.
In some patients this does not occur, and the parathyroid glands continue to function abnormally despite normal kidney function—a condition termed tertiary hyperparathyroidism. Treatment for tertiary hyperparathyroidism is similar to that for secondary hyperparathyroidism: the removal of the majority of the parathyroid glands with preservation of some parathyroid tissue to regulate calcium levels following surgery.
The primary treatment for hyperparathyroidism is surgical removal of the abnormal parathyroid glands while leaving normally functioning parathyroid tissue in place. For the most common form of hyperparathyroidism, primary hyperparathyroidism, this involves removing one enlarged, abnormal parathyroid gland in about 80 to 90 percent of patients. The remaining 10 to 20 percent of patients may have more than one gland that is abnormal, so more than one gland will need to be removed.
The goal of the procedure is to remove all the abnormal parathyroid glands while keeping the normally functioning parathyroid glands in place to regulate the calcium in the blood.
There are several techniques and variations in the approach to parathyroidectomy, or removal of parathyroid glands. The two most common are exploration of all four glands or a minimally invasive (also known as directed or focused) parathyroidectomy, or a technique involving preoperative testing to attempt to locate the abnormal parathyroid gland and focus the surgical approach toward that abnormal gland. These preoperative tests can include parathyroid ultrasound, parathyroid sestamibi scan (a radioactive scan), gamma probe localization with radioactive administration, magnetic resonance imaging (MRI), computed tomography (CAT) scan, or directed blood sampling. Experienced endocrine surgeons use a variety of these localization studies to allow for a minimally invasive approach.
Minimally invasive parathyroidectomy is performed through a smaller incision—typically 1.5 to 3 centimeters in length—and requires less operative dissection than an exploration of all four parathyroid glands. The level of parathyroid hormone in the blood is measured during surgery to confirms the removal of the abnormal parathyroid tissue and the functionality of the remaining parathyroid glands.
If the level of the parathyroid hormone level decreases enough to meet the surgeon's defined criteria, the operation is completed without examination of all of the parathyroid glands. A hormone level that does not decrease is a sign of additional abnormal parathyroid tissue in the glands, which requires further surgery and follow-up testing.
The risks of surgery are low but include bleeding, which may require a return to the operating room. The risk of infection is extremely low for parathyroidectomy, and antibiotics are typically not administered in the operating room for this procedure. There is a very small risk of injury or damage to the nerves that control the muscles of the vocal cords and voice box that can cause temporary or permanent hoarseness of the voice. Finally, if more than one parathyroid gland is removed, there is a risk of removing too much parathyroid tissue, which results in a need for long-term or lifelong calcium supplementation in the form of calcium pills.
Following surgery, most patients may be discharged the same day after a short stay in the recovery room. Patients that stay overnight are usually discharged the following morning. Pain at the surgical site can usually be controlled with over-the-counter medications like ibuprofen or acetaminophen such as Tylenol.
Following successful surgery and the return of the parathyroid hormone level to normal, the calcium level in the blood also returns to normal over the next two to three days. During this time the bones begin to absorb the calcium that has been lost due to hyperparathyroidism, and the level of calcium in the blood can drop below normal. By taking calcium supplementation in the form of over-the-counter calcium pills, the symptoms of low calcium, which include numbness and tingling in the extremities and around the mouth, can be minimized.
Most patients can return to normal activities one to three days following the procedure, and symptoms will improve over the next few weeks to months. For more information regarding postoperative instructions, please see the Montefiore Thyroidectomy and Parathyroidectomy Patient Discharge Instructions.
Finding an experienced surgeon to perform a parathyroidectomy is an important decision. Several research studies have demonstrated the benefits of experience and expertise in parathyroid surgery on the risks, the degree of invasiveness and the operative success in the surgical treatment of hyperparathyroidism. Our surgeons are dedicated to the treatment of endocrine disorders and have the resources to treat diseases.