My calcium levels have been normal (around 9.5 mg/dl) but my PTH is consistently elevated, between 60 to 80 pg/ml (normal range up to 65 pg/ml). Do I have parathyroid disease?
Most of the time, this clinical picture does not indicate primary hyperparathyroidism. The PTH is a little bit over the “normal” range, but with calcium levels that remain in the normal range, a parathyroid tumor is unlikely. If your calcium level were high (that is, over around 10.0 mg/dl for adults over age 40), then I would diagnose primary hyperparathyroidism. But with normal calcium levels that is not likely (we would want to check the calcium a few times and make sure it stayed normal).
If your calcium level is always normal, then the most likely explanation is that your parathyroid glands are working hard to keep the calcium in normal range (a form of mild secondary hyperparathyroidism). This could be a result of problems with absorbing calcium or not having enough calcium in the diet. A chronically low Vitamin D level will make it difficult to absorb enough calcium, which could produce these lab results also.
I would want to check the Vitamin D level to see if Vitamin D deficiency was the cause. I would also want to get more of your medical history. A history of a gastric bypass would account for these labs - with a gastric bypass, the intestines will always have a little trouble with absorbing calcium, and thus the PTH level will often be a little higher than normal (lifelong).
Overall, we need a little more information: more calcium and PTH levels, Vitamin D levels, and medical history (specifically gastric bypass or any other intestinal problem).