Since a “normal” PTH level is typically between 20 and 50 pg/ml, your parathyroid hormone level is definitely high. But we don’t yet have enough information yet to know why.

To figure out why your PTH level is high, we need to know your calcium level. Parathyroid glands are designed to respond to blood calcium levels. When the calcium level is low, they make more hormone (PTH) in order to bring the calcium up. When your calcium level goes too high, the parathyroid glands make less PTH so that the calcium can drop back down. If your calcium level is in the normal range (i.e. in the mid to high 9s mg/dl for adults over 40) then your PTH should also be in the normal range.

If your calcium is low or low-normal (e.g. in the 8s or low 9s in mg/dl), then we would expect the parathyroid glands to make more PTH. In this case, a PTH of 91 pg/ml is actually appropriate. This is called secondary hyperparathyroidism. You can read more about it here: https://www.southwestparathyroid.com/secondary-hyperparathyroidism

On the other hand, if your calcium level is high (above 10.0 mg/dl for adults over 40), then a PTH of 91 is not appropriate. A high calcium with a PTH of 91 indicates primary hyperparathyroidism. You can read more about that here: https://www.southwestparathyroid.com/disease

It is better to think of PTH in terms of “appropriate” vs. “not appropriate” rather than “normal” vs. “abnormal.” A PTH of 91 is appropriate for a low calcium, but inappropriate for a normal or high calcium. It’s important to distinguish primary hyperparathyroidism from secondary hyperparathyroidism, because the treatments are very different. The only cure for primary hyperparathyroidism is surgery, but secondary hyperparathyroidism is treated with supplements and sometimes medications.