If you remember from last week’s post, hyperparathyroidism is a condition where the parathyroid glands are making too much hormone (PTH). Primary hyperparathyroidism is when one or more of the parathyroid glands goes haywire and makes too much hormone. Secondary (and tertiary) hyperparathyroidism are when an outside influence (usually kidney failure causing abnormal blood calcium levels) triggers the parathyroids to make too much hormone.
How are patients with hyperparathyroidism diagnosed? As stated in the last post, there are not obvious hallmark symptoms of hyperparathyroidism. Usually the first sign that something is awry is an elevated blood calcium level (frequently done on routine testing). As part of the diagnostic workup for elevated calcium, a PTH blood level will be ordered and will usually be elevated. At this point, a diagnosis of hyperparathyroidism can be made. If you don’t have kidney failure or another obvious trigger, we can presume you have primary hyperparathyroidism.
It should be noted that a normal PTH level with elevated calcium level is STILL diagnostic for hyperparathyroidism. If the parathyroid glands were functioning normally, the PTH level should be very low if the calcium is elevated.
We know that 80-90% of cases are when one of the 4 glands grows into an adenoma, or benign tumor. 10-20% of cases are multiple adenomas or enlargement (hyperplasia) of all four glands. Less than 1% of the time, there is a parathyroid cancer.
Once a patient has been diagnosed with high calcium and PTH levels, I like to try and localize an adenoma to one of the four parathyroid glands. A simple ultrasound of the lower neck is useful for this purpose. I also typically order a SPECT/CT scan- this is a nuclear medicine test which is also helpful for localizing an adenoma.
Normal parathyroid glands are typically not visible on radiologic imaging, so if there is a visible mass behind/around the thyroid on either of these scans, it is likely to be the parathyroid adenoma. Ultimately, the ultrasound and SPECT/CT are helpful but not definitive at identifying exactly where the problem is.
Once the imaging has been done, the patient is scheduled for surgery. Most of the time, there is visual evidence of an enlarged parathyroid on one or both of the preoperative scans. In this case, the exploration can be directed to the suspicious area (for example, the left inferior parathyroid).
Prior to the incision, I’ll send a blood sample for rapid PTH testing- this will let me know the patient’s PTH level within a few minutes. After removing the adenoma, the PTH level will drop rapidly in the blood (its half life is only about 10 minutes).
The enlarged adenoma is usually identified pretty easily. Once I remove it, I’ll send it to the pathology lab for confirmation that it is parathyroid tissue. After about 20 minutes, I’ll send another blood sample for rapid PTH testing. If the PTH level has dropped by more than 50%, the surgery is done. If it has not dropped that much, I will continue inspecting the other parathyroids to look for a second adenoma or hyperplasia of the other glands. In cases of hyperplasia, typically 3 1/2 of the 4 glands must be removed.
For patients with secondary and tertiary hyperparathyroidism due to kidney failure, a 3 1/2 gland resection is also performed as the standard treatment.
The risks and potential complications of parathyroid surgery are the same as thyroid surgery.
Parathyroid surgery can be quite challenging in some cases due to the variable anatomy/location of the parathyroid glands. There is always the low possibility that an adenoma is low down in the chest and a patient won’t be cured by the first surgery. Fortunately, most patients are easily cured by removal of a single adenoma.