This happens in about 10% to 15% of cases of primary hyperparathyroidism. It’s called parathyroid hyperplasia.

When I operate, I examine all four parathyroid glands. In most cases, there is just one bad one (a benign adenoma). In some cases I find multiple adenomas. And in other cases I find hyperplasia, when all four parathyroid glands are bad. If there is just one adenoma, I can remove that and leave in three normal glands. But with hyperplasia, I don’t want to remove all of the bad glands. You still need some parathyroid tissue to regulate your blood calcium level!

The treatment for hyperplasia is what we call a subtotal parathyroidectomy, meaning you take out most of the parathyroid tissue, but leave some behind. Usually this will be a remnant of the most normal-looking parathyroid. I choose the best looking gland (the smallest, or most normal-appearing) and leave a piece of this gland behind that is about the size of a normal parathyroid gland. Once I confirm that the remnant looks adequate, I remove the other parathyroid glands. I will also mark the area of the remaining parathyroid tissue with a bright blue marking suture, to allow me or another surgeon to find it again if necessary.

Primary hyperparathyroidism caused by hyperplasia acts just like primary hyperparathyroidism caused by an adenoma. It is the same disease. The symptoms are the same. The operation is just a little different. The outcomes are typically the same. Most people with hyperplasia are cured with a subtotal parathyroidectomy and do not require further surgery.

Note that it normally isn’t possible to diagnose hyperplasia before the operation. A negative scan does not automatically mean that you have hyperplasia!