Most people have four parathyroid glands, one located on each of the corners of another gland, the thyroid, which is located in the lower neck, partially surrounding the windpipe like a horseshoe. In spite of the similarity in name and location, the parathyroid glands and thyroid gland are separate glands with very different functions.
The parathyroid glands, unlike the thyroid which regulates metabolism, produce a hormone that helps maintain the proper balance of calcium and phosphorus in your body.
In hyperparathyroidism, your parathyroid glands produce too much parathyroid hormone. Most often, there is an accompanying elevation of calcium in the bloodstream. The resulting imbalance in calcium and phosphorus can create a multitude of health problems — including affecting your teeth, bones, nervous system and muscles.
Treatment depends on several factors, including which type of hyperparathyroidism you have.
Symptoms of Hyperparathyroidism:
The majority of people with hyperparathyroidism have no signs or symptoms. The elevated Calcium is detected on routine blood testing. In those who do, the symptoms frequently come on slowly and are usually subtle, such as a feeling of weakness or fatigue, or vague aches and pains. But more severe signs and symptoms can develop over time. These include:
- Increased thirst and urination due to increased excretion of calcium in the urine (hypercalciuria)
- Kidney stones (nephrolithiasis)
- Heartburn or abdominal pain from peptic ulcer disease or pancreatitis
- Nausea, vomiting or loss of appetite
- Thinning bones (osteoporosis), leading to an increased risk of fractures
- Confusion or poor memory
- Muscle weakness or fatigue
Having too much parathyroid hormone can lead to several serious problems including:
- Osteoporosis. Hyperparathyroidism poses a long-term threat to your bones — the more parathyroid hormone your parathyroid glands produce, the more calcium your bones lose. The result is weak, brittle bones that are prone to fractures.
- Kidney damage or kidney stones. Because your body tries to compensate for excess calcium by excreting more of the mineral in your urine, you’re at increased risk of kidney damage or kidney stones.
- Peptic ulcers. High blood levels of calcium stimulate your stomach to produce more acid, making you more likely to develop peptic.
- High blood pressure. High calcium levels can put you at increased risk of high blood pressure (hypertension) and congestive heart failure.
Why Calcium is Important:
Calcium is the most abundant mineral in your body, best known for its role in keeping your teeth and bones healthy. But calcium also helps your blood clot, aids in the transmission of signals in nerve cells and is involved in muscle contraction. Phosphorus, another mineral, works in conjunction with calcium in these areas.
The parathyroid glands maintain proper levels of both calcium and phosphorus in your body by turning the secretion of parathyroid hormone (PTH) off or on, much as a thermostat controls a heating system to maintain a constant air temperature. Vitamin D also is involved in regulating the amount of calcium in your blood, and its actions work in tandem with parathyroid hormone.
Normally, this balancing act works well. When calcium levels in your blood fall too low, your parathyroid glands secrete enough PTH (parathyroid hormone) to raise the calcium. This occurs because PTH raises calcium levels by releasing calcium from your bones and increasing the amount of calcium absorbed from your small intestine. When blood calcium levels are too high, the parathyroid glands normally produce less PTH. But sometimes one or more of these glands produce too much hormone, leading to abnormally high levels of calcium (hypercalcemia).
Types of Hyperparathyroidism: PRIMARY HYPERPARATHYROIDISM & SECONDARY HYPERPARATHYROIDISM.
- Primary hyperparathyroidism. Usually, this type is caused by a benign growth (adenoma) on one of the 4 parathyroid glands, although the disorder can also occur when two or more glands become enlarged (hyperplasia) and produce too much hormone. In rare cases, hyperparathyroidism may be caused by cancer of one of the parathyroid glands.(very rare)
- Secondary hyperparathyroidism. This less-common type occurs when another medical condition causes the parathyroid glands to produce too much PTH in response to chronically low levels of circulating calcium. Kidney failure is by far the most common cause of this condition. However, malabsorption problems and rickets, a disease caused by severe vitamin D deficiency, are other less common causes of this type of hyperparathyroidism.
Diagnosis of Primary Hyperparathyroidism:
The diagnosis of primary hyperparathyroidism is nowadays made by noting elevation of serum calcium along with an elevation of the intact PTH (parathyroid hormone) level. While there are occasionally other conditions which can share this abnormality, it is almost always due to primary hyperparathyroidism. Other tests which can assist the physician include measurements of serum ionized calcium, Vitamin D levels (25-hydroxy and 1,25 hydroxy-cholecalciferol), phosphorus, and kidney function tests. Measurement of urinary calcium (24 hour collection) and bone densitometry may also be requested. Localizing imaging tests include the Cardiolyte (Technetium Sestamibi) scan and ultrasonography. Ultrasonography can also identify associated pathology i.e. nodules, masses or tumors, within the thyroid gland which might necessitate evaluation before surgery for the parathyroid problem is recommended. The principle behind these tests is to 1) confirm that the patient does indeed have primary hyperparathyroidism as the cause of his/her hypercalcemia (elevated blood calcium) as opposed to some other cause (beyond of the scope of our discussion), 2) establish the severity of the disorder, 3) determine whether the patient fulfills the critieria appropriate to recommend surgery, and 4) to localize the abnormal parathyroid gland(s) causing the problem.
There are subgroups of patients who have a familial or hereditary variant of primary hyperparathyroidism. Some are found in association with so called MEN or Multiple Endocrine Neoplasia syndromes in which patients have tumors or other endocrine organs. The diagnosis and approach to these subgroups is considerably different than sporadic typical primary hyperparathyroidism.
Treatment of Primary Hyperparathyroidism:
Surgery is the mainstay of treatment of primary hyperparathyroidism. The goal is to remove the “tumor” or adenoma which causes the condition in most patients. In the 10 – 15% of patients who have Hyperplasia or multiple Adenomas, exploration and removal of all offending glands is necessary.
The last several years has seen a major change in the surgical approaches to the disease focusing on more minimally invasive outpatient approaches. This requires surgical experience and expertise.
Traditionally, the surgery involved a long incision, exploration on both sides of the neck and general anesthesia. While there is nothing wrong with this approach, more contemporary techniques such as minimally invasive radioguided parathyroidectomy, may be preferred for selected patients. In this procedure, we use a radioisotope scan ( Cardiolyte or Sestamibi scan) to help locate a tumor or abnormal parathyroid gland before surgery. For the scan, you’re given a very small dose of a radioactive material that’s absorbed more selectively by the overactive parathyroid gland — in deference to the healthy ones. A Nuclear Camera images the neck and identifies the abnormal parathyroid gland. Using similar technology transferred to the Operating room, the surgeon uses the sestamibi scan along with a radioguiding probe to locate the abnormal gland. The probe detects radioactivity, much as a Geiger counter does, and assists in identification of the parathyroid tumor using a smaller incision. Thus, unlike the surgery of yesteryear, a directed or focused parathyroidectomy can be done in many patients whose scan identifies the tumor before surgical exploration.
Sestamibi scanning is not the only way to identify abnormal parathyroid glands and tumors. Ultrasound done by the surgeon in his office or in the radiology suite can identify a parathyroid tumor in many patients. Like the scan, this can anatomically localize the parathyroid growth and allow the surgeon to perform a more minimally invasive approach than might otherwise be necessary. Ultrasound and Sestamibi scans are often both used and enhance the confidence of localization of the abnormal parathyroid tumor.
Another technique used by surgeons to verify that a directed, or focused, minimally invasive parathyroidectomy has been complete involves so called ‘quick PTH assay’ which is done intraoperatively. Since parathyroid hormone (PTH) is rapidly metabolized, its measurement 10 minutes after the surgeon removes the abnormal gland or tumor can be used to physiologically verify that no other abnormal parathyroid tissue has been left behind. While not always necessary, this measurement can enhance the confidence of the surgeon in achieving success when performing an operation in which all 4 parathyroid glands are not identified.
A parathyroidectomy can be performed through a small incision when the tumor is clearly identified ahead of time. However, it must be emphasized that the length of the incision is less important than the skill of the surgeon. Most scars are barely noticeable within a month of surgery regardless of length. The operation usually takes less than an hour and can be done either under local or general anesthesia. When local anesthesia is used, the anesthesiologist may inject some of the regional nerves prior to the surgery (regional block), and the patient is given some sedation. Regardless of which type of anesthesia is given, most patients can go home within a few hours of the surgery. Pain is often nominal, and easily controlled with minimal oral pain medication.
While parathyroid surgery is rarely complicated, factors such as prior surgery in the area, morbid obesity, and bleeding tendencies can pose hazards. Like all surgery, there are some risks which can be kept to a minimum in experienced hands. There is a small risk to injury of the nerve to the vocal cord(s). That risk should be well under one in a hundred patients. Other patients may experience precipitous drops in their serum calcium levels requiring treatment with calcium and vitamin D. In addition, although it’s usually very effective, parathyroid surgery won’t cure the problem in every case. Some patients develop recurrence of the problem in the remaining glands or have unrecognized second tumors which become evident later.
There has been increasing interest in use of Endoscopes to assist in performing minimally invasive parathyroid surgery. So-called Minimally Invasive VideoAssisted and VideoEndoscopic Parathyroidectomy are being touted as improvements on current techniques. Thus far, these approaches have not been proven to be more beneficial to patients in experienced hands, and may be more costly. They have been used as marketing tools to lure patients to centers or practices offering the technology.
At ENTA – Head and Neck, we offer all contemporary approaches to the diagnosis and management of Parathyroid Disorders. Extensive experience with large numbers of patients has afforded us perspective on which techniques are best suited to individual patients. Considerable counseling and patient education is provided so that patients can make informed decisions about how they would like to be treated for their parathyroid disorder.
Secondary Hyperpararthyroidism is usually the result of chronic renal insufficiency or kidney failure. Most patients are on hemodialysis. It is characterized by pronounced overproduction of parathyroid hormone resulting from so-called end organ resistance to parathyroid hormone. Unlike primary Hyperparathyroidism, calcium is usually low or normal, and phosporus is elevated. The clinical manifestations include all of the effects of renal failure, and may include bone and joint pain and limb deformities in severe cases. In the worst form of the disease, renal osteodystrophy develops with multiple skeletal manifestations. Aside from chronic renal failure, secondary hyperparathyroidism may develop in association with vitamin D deficiency, malabsorption syndromesand rarely due to chronic overuse of furosemide.
With appropriate treatment, such as renal transplantation or vitamin D supplementation, the changes related to secondary hyperparathyroidism may resolve. Long-standing secondary hyperparathyroidism associated with extensive glandular hyperplasia may not revert. In the patients with this condition, tertiary hyperparathyroidism should be considered.
Tertiary hyperparathyroidism develops in patients with long-standing secondary hyperparathyroidism, which stimulates the growth of an autonomous adenoma. A clue to the diagnosis of tertiary hyperparathyroidism is intractable hypercalcemia and/or an inability to control osteomalacia despite vitamin D therapy.
Surgery for secondary and tertiary hyperparathyroidism is occasionally indicated in patients failing to respond to medical management. Newer drugs such as the calcimimetic agent, Sensipar, are helping manage chronic renal failure patients with secondary hyperparathyroidism. In patients with tertiary hyperparathyroidism, surgery may be necessary especially prior to renal transplantation. Unlike surgery for primary hyperparathyroidism, surgery for this disease require 4 gland explorations, and removal of most or all of the hyperfunctioning parathyroid tissue. This at times requires cryopreservation of some parathyroid tissue for future reimplantation should hypoparathyroidism result.