I have had calcium levels of 11.00, 11.1, and 10.6 over the last three months. The PTH level was 66 one month ago. Now my PTH is 36. My only symptoms are fatigue, apathy, and "feeling old". I'm 61 and otherwise in very good health. I was originally diagnosed with mild hyperparathyroid, but now the endocrinologist says that it might be something else and wants to re-test everything in months. What would cause the PTH to fluctuate like this?