In most cases, persistently high calcium levels indicate primary hyperparathyroidism. But we need more information to confirm the diagnosis. To diagnose primary hyperparathyroidism, we check the calcium and PTH together. If something else (not parathyroid disease) is causing the high calcium, then the normal parathyroid glands will be suppressed - that is, they will make very little hormone. The PTH would be below 20 mg/dl, in the suppressed (low) range. If the PTH is in the normal range, that is inappropriate for a high calcium. This would indicate that at least one parathyroid gland was not acting appropriately – it wasn’t “turning off” with the high calcium, like it should.

There is an aspect of this presentation that is unusual, though, and points against primary hyperparathyroidism. It would be very unusual to have primary hyperparathyroidism for 30 years and have no health effects. It’s not impossible, just not typical. I would want to know if you had any family members who also had high calcium, or if you could find any normal calcium levels in your past. There are rare familial conditions (e.g. FHH, or familial hypocalciuric hypercalcemia) that cause lifelong high calcium levels that are unrelated to the parathyroids.

Your situation is not straightforward. The next step would be to check calcium, PTH, and Vitamin D levels, ask family members about high calcium, and look for your old lab results, if available. A formal consultation with a physician is also warranted, to help figure this out.