The parathyroid glands are four pea-sized organs located near the thyroid gland at the base of the throat. They, along with the thyroid gland, are tasked with creating crucial hormones. The parathyroid glands create a hormone called PTH that regulates phosphorus and calcium levels in the body.
When a patient develops symptoms of parathyroid disease, such as a lump in the neck, trouble swallowing, difficulty speaking or something less obvious, such as weakness, fatigue, nausea, kidney stones or bone pain, investigation into parathyroid disease may be deemed necessary. Left untreated, parathyroid disease can lead to damage of the bones, kidneys, gastrointestinal system, brain and other systems, so it requires medical treatment.
Because the parathyroid glands are tiny, they can be difficult to image, demanding a highly skilled and experienced radiologist or endocrine physician to promote the utmost level of accuracy.
WHAT CAUSES HYPERPARATHYROIDISM?
There are two types of parathyroid gland overactivity, called hyperparathyroidism: primary and secondary. Secondary hyperparathyroidism is a product of the body’s response to low calcium levels resulting from poor absorption in the intestines, often related to stomach or intestinal bypass surgery, ongoing severe Crohn’s disease or celiac disease, or kidney failure requiring dialysis. Primary hyperparathyroidism is the more common condition, usually first indicated by high blood calcium levels.
Both conditions are often associated with low levels of vitamin D, which, in extreme cases, can cause secondary hyperparathyroidism, but not primary.
Primary hyperparathyroidism is caused by physical changes to one or more parathyroid glands, in order of commonality:
Adenoma - a noncancerous growth
Hyperplasia – the enlargement of two or more glands
Cancer – in rare cases
With hyperparathyroidism, too much PTH leaches calcium from the bones into the bloodstream, and/or retains too much calcium in kidneys. Untreated, it can cause an increased risk of fracture, kidney stones and a host of other sometimes serious problems.
About 70-80% of cases are caused by adenomas, which occur most often in postmenopausal women and people with kidney disease, though anyone may be affected.
DIAGNOSING PARATHYROID DISEASE
The first tests involved in diagnosing hyperparathyroidism include urine analysis to measure elements like calcium and creatine, and blood tests to look for hypercalcemia (excess calcium) and other signs of disease.
Most often, a diagnosis of primary hyperparathyroidism is made when a blood test shows abnormally high blood calcium and parathyroid hormone levels. That’s why it is so important to get regular routine medical blood tests, to catch problems like hyperparathyroidism before symptoms and possible damage occur.
Treatment for primary hyperparathyroidism due to adenoma is surgery to remove the affected gland or glands. In the case of hyperplasia, surgery is performed to remove an adequate number of abnormal cells to reduce excess PTH production and restore healthy function. Most cases can be treated via minimally-invasive parathyroidectomy, or MIP. MIP is safe, has few complications, and has a very high cure rate.
WHAT WILL A PARATHYROID SCAN SHOW?
In some cases, your doctor will order an imaging scan to assess your parathyroid glands before surgery. These scans include:
Sestamibi Scan: This nuclear medicine scan utilizes a tiny, very mild radioactive agent, which is injected into a vein and absorbed by the overactive parathyroid gland or glands for imaging by a highly sensitive gamma camera. This scan is the preferred imaging test for localizing parathyroid disease since the glands and related tumors, goiters or nodules are small enough to avoid detection by many other tests. It should be noted that the efficacy of the sestamibi scan is highly dependent on the skill of the radiologist interpreting its images, so it is important to rely on a doctor with fellowship training in nuclear medicine imaging.
Ultrasound: This simple, painless, radiation-free test can be used to examine the parathyroid glands, but again, it must be performed by professionals highly-trained in parathyroid ultrasound imaging and interpreted by radiologists who subspecialize in parathyroid imaging for ultimate accuracy.
Because of the tiny size of the parathyroid glands, imaging tests like CT and MRI are not typically used for preparation for hyperparathyroidism surgery.
VISIT RAO FOR NUCLEAR MEDICINE AND PARATHYROID SCANS
RAO offers the sestamibi scan, also called a nuclear medicine parathyroid scan, at our Medical Imaging Center at Windsor Oaks. Accredited in nuclear medicine by the American College of Radiology, our state-of-the-art facility features a team of fellowship-trained radiologists, including specialists in diagnostic radiology and nuclear medicine, for optimal accuracy and the gold standard of care.
