How Surgeons Decide Which Parathyroid Glands to Remove
Once a decision for surgery has been made and the surgeon has selected the desired imaging prior to the surgery, what actually takes place during the operation? How does the surgeon determine which gland or glands are abnormal?
The answers to these questions are not quite as straightforward or consistent among surgeons as one might expect. There are a variety of gland characteristics that a surgeon can rely on to decide which glands to remove. These characteristics include:
- The findings on preoperative imaging
- The shape, size, and color of the individual glands
- Comparison of the four glands during the surgery
- Measurement of PTH drop following removal of one or more glands
- Pathologic assessment of the gland, either by frozen section (available during the surgery, but adds time) or permanent section (only available a few days after)
In practice, these five inputs tend to sort surgeons into two broad philosophies.
Philosophy 1: Trust the imaging, find the one gland
Some surgeons rely heavily on preoperative imaging to decide if they can select a single gland to locate and remove. These surgeons typically will not recommend surgery unless at least one, and preferably two, preoperative imaging tests point to a single gland as the culprit. Given this selectivity, the operation is focused on finding only one gland presumed to be abnormal.
Once it’s identified, the surgeon typically uses intraoperative PTH measurement to see if the level has dropped. If it hasn’t dropped enough, the operation is extended to look for the other glands, with PTH rechecked after any additional glands are removed until the level falls sufficiently.
Some surgeons in this camp also send every removed gland for frozen section to confirm it’s parathyroid tissue and to get the pathologist’s estimate of “hypercellularity.” That said, there’s no real consensus on whether hypercellularity correlates with PTH overproduction, so it’s debatable how useful that feedback actually is, and sometimes the pathologist can’t even confirm the tissue is parathyroid gland from the frozen section alone.
The tradeoff: if the preoperative imaging is accurate and the PTH level drops sufficiently, this can be the least invasive approach. But imaging can localize one abnormal gland while missing a second one that doesn’t show up and the PTH value might still drop enough to look like a cure even though an abnormal gland remains. Those patients sometimes aren’t discovered to have persistent hyperparathyroidism until lab work at six months shows the calcium is still high. And if the PTH doesn’t drop after the single gland comes out, relying on intraoperative measurements can significantly prolong the surgery, since each result takes about 20–30 minutes to come back.
There’s also a judgment call baked into this approach: what PTH level counts as evidence of cure? Historically, surgeons have accepted a level that’s 50% or less of the preoperative value but that criterion can be misleading, especially when the starting PTH was very high.
Philosophy 2: Find all four glands, every time
Other surgeons choose to identify all four glands at the initial operation regardless of what the preoperative imaging showed. The imaging becomes a roadmap rather than a limit; the surgeon incorporates it with what’s actually seen at surgery. The glands flagged by sestamibi scan, ultrasound, or other imaging are expected to appear abnormal and are removed; the remaining glands are exposed to confirm they look normal, or “dormant.”
Some patients have what’s called four-gland hyperplasia, where all four glands are contributing to the hyperparathyroidism to varying degrees. In these patients, all four glands may look similar, each with some abnormality, but not necessarily large. Here the surgeon must identify the most normal-appearing gland, leave a portion of it in place, and remove the other three completely.
Intraoperative PTH measurement isn’t routinely needed with this approach, since it’s a safe assumption that identifying and removing the abnormal gland(s) from all four will cure the patient. PTH is simply checked later, in recovery or at a follow-up visit.
The tradeoff: this approach doesn’t depend on positive preoperative imaging and skips the extra operating-room time for intraoperative PTH. But it’s more invasive, since dissection extends to all four glands, which raises the incidence of temporary hypocalcemia (and, rarely, prolonged or permanent hypocalcemia if the “normal” glands’ blood supply is compromised during dissection). More extensive dissection also means a higher chance of temporary hoarseness after surgery, though this is almost always transient.
Neither approach is simply right
Both philosophies are defensible, and the best surgeons choose deliberately based on the quality of their imaging, their patient population, and how much operative time they’re willing to spend chasing a PTH number. But deciding on a philosophy is only the first challenge. Once you’re actually in the neck, you still have to answer a much more concrete question: what does an abnormal gland actually look like? That’s the subject of the next post in this series.
