Do I have just one parathyroid gland with disease?

Maybe. 80% of patients with primary hyperparathyroidism have single gland disease. But it is important to prove that. Find an experienced endocrine surgeon. You might look at the american association of endocrine surgeons website to find someone in your area.
Why you say that? What is wrong with you Do you have HYPERPARATHYROIDISM OR parathyroid ADENOMA if that is the case,yes most of the time it is one gland involved Askl your doctor or endocrinologist.
Most of the time. 85% to 90% of patients with hyperparathyroidism have a single parathyroid adenoma. The remainder of the time this is due to two or more glands.