Parathyroid Mass: Evaluation and Management
Although most people have some idea of what a thyroid is, when it comes to the parathyroid glands, most confuse it as being a part of the thyroid gland with similar functions. However, although the parathyroid gland is located within the thyroid gland and contains the word "thyroid" in its name, it is completely different in both form and function. As such, evaluation and management of parathyroid masses is also completely different from thyroid masses.
Before getting into what should be done, first a little anatomy lesson. I promise, it will be just enough anatomy in order to understand treatment.
If you look at the picture of the woman below, the arrow points to the thyroid gland which is shaped like a butterfly and overlies with windpipe (trachea). Triangle arrow-heads point to nerves (yellow) which is found under the thyroid gland and is what makes the vocal cords move.
If you turn the thyroid gland around and look at it from behind (see picture above), there are 4 little glands known as parathyroid glands. Although classically, these glands are located at the 4 corners of the thyroid gland, considerable variation exists in where they might be located including nowhere near the thyroid (behind the esophagus or even around the heart). These special glands secrete a hormone called parathyroid hormone (PTH) which regulates the level of calcium and phosphorous in the blood and bones within a very narrow range so that the nervous and muscular systems can function properly.
This function is unlike the thyroid which secretes a completely different hormone which regulates how quickly the body uses energy, makes proteins, and how sensitive the body is to other hormones.
More on why these structures are important below (under risks of parathyroid surgery).
There are generally two situations in which a parathyroid mass is discovered... calcium levels in the blood are found to be abnormally high or a mass is appreciated in the neck.
With elevated calcium levels, other symptoms may or may not be present including dehydration, fatigue, depression, bone pain, muscle soreness, decreased appetite, nausea, vomiting, constipation, mental impairment, kidney stones, and osteoporosis.
With elevated calcium levels in the blood, an "intact parathyroid hormone" (iPTH) level is obtained to determine whether the elevated calcium is due to concurrent high iPTH levels which would than suggest the existence of a parathyroid adenoma or carcinoma mass.
If the iPTH level does come back elevated (hyperparathyroidism), a workup is performed to try and find the parathyroid gland that is responsble for causing the abnormally high PTH. This workup would include an ultrasound to see if one (or more) of the parathyroid glands are abnormally enlarged physically as well as a sestamibi scan (shown below; image by Myohan at Wikipedia) to visualize an abnormally hyperactive gland. Both studies complement each other to help the surgeon determine which parathyroid gland(s) to remove in order to correct the hyperparathyroidism thereby leading to calcium level normalization.
Depending on the clinical situation, a CT neck with contrast may also be obtained as well as an ultrasound guided needle biopsy.
With surgical removal, one ONLY wants to remove the abnormally hyperfunctioning parathyroid gland(s). Normal functioning glands are to be left alone as your body needs some parathyroid glands to help regulate calcium levels. Without any parathyroid glands, calcium levels will bottom out which would cause life-threatening cardiac arrhythmias.
The most common cause for hyperparathyroidism is parathyroid adenoma and surgical removal is curative. Less commonly, cancer may be present due to a parathyroid carcinoma which would require aggressive surgical removal of not just the culprit gland, but the entire thyroid as well as surrounding tissues and lymph nodes.
Parathyroid Surgery (Parathyroidectomy)
Removal of the parathyroid gland can potentially be a very simple affair or VERY difficult.
Best Case Scenario
The ultrasound and sestamibi scan both show a single abnormally large or hyperfunctioning gland in a specific location in the thyroid gland (for example, left inferior thyroid pole). An incision is made overlying the thyroid, but shifted slightly to the side of the abnormal parathyroid gland. Dissection is carried down to the abnormal parathyroid gland (depicted by arrow; image by THWZ in Wikipedia) and removed. Intra-operative intact parathyroid hormone (iPTH) levels are than measured and if normal, the skin is closed and patient allowed to go home a few hours later. The enire surgery may last about 30 minutes.
Not-So-Best Case Scenario
In this situation, the parathyroid gland that is thought to be abnormal is removed... but the intra-operative iPTH levels are still abnormally high. This means that there is another abnormal parathyroid gland present that needs to be removed. But which one? Typically the surgeon will review again the ultrasound and sestamibi scan to try and figure out which gland next to remove. Intraoperative ultrasound and/or radioisotope localization may even be performed to guide which next gland to remove. Ultimately, all four parathyroid glands may end up being evaluated with frozen section pathology analysis to evaluate for presence or absence of adenoma. Once pathology reveals which gland contains adenoma, that gland is than completely removed... and hopefully iPTH levels will normalize. Overall, the surgery may last about 2 hours if all four parathyroid glands end up being evaluated.
Worst Case Scenario
Rarely, all four parathyroid glands are checked out and comes back normal or one is missing... suggesting an ectopic parathyroid gland that is not located in the usual locations within the thyroid gland. In this unfortunate situation, the parathyroid adenoma may be located "somewhere else" including behind the esophagus or even somewhere around/above the heart. Possible locations are denoted as black circles in picture to right. Although the surgeon may attempt to search for the missing parathyroid gland in all these areas, it is not unusual for the surgeon to "give up" and wake the patient up without identifying and removing the culprit parathyroid adenoma. CT or MRI scan of the neck and upper chest is often ordered to try and find the "missing" parathyroid adenoma as well as repeating the Sestamibi scan.
Risks of Parathyroid Surgery
Beyond being unable to find the culprit parathyroid gland as well as the usual bleeding and airway complications that occur with any type of neck surgery, parathyroid surgery has two unique risks associated with it.
Remember the anatomy lesson at the top? There are two key structures that are at risk with parathyroid surgery: the parathyroid gland itself and the nerves that go to the vocal cords.
Lets talk about each one separately with its associated risk.
As a reminder, the 4 parathyroid glands are responsible for regulating the calcium levels in the blood. Without the four parathyroid glands, the calcium levels will drop precipitously leading to heart arrhythmias and potentially cardiac arrest resulting in death. This situation may occur when all 4 parathyroid glands are biopsied and/or damanged when the surgeon accidentally removes or cuts-off the blood supply to the parathyroid glands. You need parathyroid glands (or at least some of it) for survival!!!
A patient does not necessarily need all four to survive. It's also possible that the parathyroid glands may be "stunned" by the thyroid surgery and temporarily malfunction resulting in transient calcium level decrease which can be addressed with vitamin D and calcium pill supplementation.
To maximize parathyroid gland survival, either the blood supply be preserved to the remaing parathyroid glands OR normal parathyroid gland is minced up and embedded in muscle which has a rich blood supply, a procedure called parathyroid gland auto-transplantation. Typically, the parathyroid gland is deposited into the sternocleidomastoid muscle or the forearm if parathyroid gland hyperplasia recurrence is possible (easier to monitor and remove in the future). Usually, it may take 4-6 weeks for the parathyroid auto-transplant to start working.
The nerves that go to the vocal cord (arrowheads) travel between the thyroid gland and the trachea/esophagus. Known as the "recurrent laryngeal nerve," one or both nerves may get accidentally cut during thyroid surgery resulting in complete vocal cord paralysis. With vocal cord paralysis, the voice becomes very breathy with talking. Aspiration may also occur. Depending on whether one or both nerves are cut, treatment to address the resulting hoarse voice is different. Click to read more about the treatment of unilateral vocal cord paralysis or bilateral vocal cord paralysis.
Of particular importance to singers, there is also another nerve near the top of the thyroid gland called the "superior laryngeal nerve" which if cut during surgery, a patient can talk just fine... but when singing, there is loss of upper range and falsetto. Unfortunately, there is no good fix for this if it happens.
What to Expect after Parathyroid Surgery
Assuming no complications and the parathyroid adenoma has been removed completely, recovery and pain resolution is fairly quick (within one week). It is not unusual to be discharged home the same day of surgery. If all four parathyroid glands were biopsied/removed/damaged, hospitalization for 1-3 days or longer may occur to monitor and ensure calcium stability. It is not unusual to have surgical drains placed during the first several days to prevent a hematoma from forming if extensive dissection was performed. Routine wound care to the incision with bacitracin ointment application is required for 1-2 weeks.
Final pathology results take about 1 week at which time a definitive diagnosis of adenoma or cancer can be made if present and subsequent care can be pursued. Click here to see why it takes so long to get a final diagnosis.
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