Parathyroid glands have the most un-predictable anatomy in the human body. Parathyroid glands are typically found on the back side of the thyroid gland. In fact, about 85% of parathyroid glands are found here. The picture on the right shows the BACK SIDE of the thyroid gland, showing that the four parathyroid glands are closely associated with the back of the thyroid. HOWEVER, because of how parathyroids are formed (when we are in our mother's womb), they can be anywhere in the neck from just below the jaw--all the way down into the chest next to the
Many experts feel that no study or test is required to "identify" the diseased parathyroid gland (or glands) prior to an operation for hyperparathyroidism. They feel that surgeons with enough experience can find the problem gland and remove it to cure the disease in about 95 % of all cases...without any pre-op tests. Of course what they don't tell you is that this requires the patient to be under general anesthesia for two to five hours so the surgeon can make a large incision and do an extensive dissection of your neck. They have to...if they want to 'explore' the neck to find the bad gland based upon their experience of where they have found them in the necks of other people. The days of doing this on all patients with parathyroid disease ARE GONE!
It is now well accepted that the preferred way to perform parathyroid surgery is to identify the over-active parathyroid gland preoperatively (before the operation). It is well established now that this localizing step will allow a shorter operation and a more successful operation. There is NO REASON for any patient to undergo parathyroid surgery without the surgeon and radiologist performing at least ONE localizing study prior to the parathyroid operation. Note: Not all patients will have a localizing test that shows the bad gland. Some people (about 6-7%) will have 4 bad glands (read more), thus their test will be negative. Even some people with only one bad parathyroid will NOT have a positive test. Keep reading more to understand this.
The following list describes briefly the different tests which may help a surgeon or endocrinologist find the diseased parathyroid gland which is over secreting parathyroid hormone.
The Sestamibi Scan is now the preferred method for identifying a diseased parathyroid gland prior to an operation. No other test comes close to its accuracy. Almost 100 percent correct when it shows a single gland. There are technique differences which make these scans at some hospitals much better than they are at other hospitals. Regardless of where it was performed however, if it shows a single adenoma, it is nearly always correct!
SPECT scanning is a new mechanism by which a three dimensional picture can be obtained following injection of Sestamibi radiopharmaceutical. Sometimes this can be very helpful, but is rarely needed prior to the first operation.
MRI scans can be extremely valuable (when positive) for localizing a parathyroid adenoma although the sestamibi has decreased the need for it dramatically. At best, an MRI will find less than 10% of diseased parathyroid glands, therefore, the indications for getting this scan are VERY few. NOT a routine test! DO NOT GET THIS TEST... IT WILL BE A WASTE OF TIME!!!!
CT scans are used much less frequently since the introduction of the MRI and Sestamibi scans. They can almost never be helpful, but getting a CT scan prior to a first operation for hyperparathyroidism is NEVER warranted. If your doctor orders this test, then find another doctor. It clearly means they know little (or nothing!) about parathyroid disease. DO NOT GET THIS TEST... IT WILL BE A WASTE OF TIME. PLEASE HEED OUR ADVICE... DO NOT GET THIS TEST EVER!
Ultrasound is inexpensive, easily performed, carries no significant risks, and can occasionally be useful in localizing a parathyroid adenoma. Overall, not very good [very inaccurate in most settings]. This test is way overused, and has been replaced by the Sestamibi. Can be helpful for those rare patients who are undergoing a second operation for hyperparathyroidism. This is in direct contrast to the utility of ultrasound for examining thyroid glands and thyroid nodules. Ultrasound is very accurate when used to examine the thyroid.