Intraoperative Parathyroid Hormone Testing
UW Health endocrine surgeons in Madison, Wisconsin, monitor the parathyroid hormone levels for patients undergoing minimally-invasive parathyroidectomy to determine if there are additional, hyperfunctioning glands.
Using the Parathyroid Hormone to Assess Glands
While the majority of patients with primary hyperparathyroidism have a single abnormal gland, up to 20 percent of patients will have either multiple adenomas or hyperplasia of all four glands.
Pre-operative imaging is not very good at identifying when patients have multiple abnormal glands. Therefore, when all of the parathyroid glands are not identified during surgery (as in a minimally invasive parathyroidectomy) it is important to have a method other than visual inspection to confirm that all of the abnormal glands have been removed.
Parathyroid hormone (PTH), which is produced by the parathyroid glands, is cleared from the blood stream very quickly, within a few minutes. Hence within five to 10 minutes of removing an abnormal gland over half of the PTH in the bloodstream will have been cleared.
By testing PTH levels pre-operatively and then again after removal of the abnormal gland you can determine if there are additional hyperfunctioning glands present.
More About PTH Testing
Endocrine surgeons look for at least a 50 percent drop in the PTH in order to consider the patient cured. If the PTH levels do not drop by 50 percent then they know that there is additional abnormal tissue and will proceed to identify the other glands to ensure that all abnormal glands are removed4.
PTH levels are typically drawn at the beginning of your operation and five, 10, and 15 minutes after the abnormal gland is removed. It can take anywhere between 10 and 40 minutes to get the results back from the PTH testing.
You are kept in the operating room while you surgeon waits for the results. The goal is to not end the operation until they have confirmation that you are cured of your hyperparathyroidism.