Is it normal to have normal ultra sounds of my thyroid and a normal sestamibi but abnormal blood work?

Yes: An ultrasound checks for anatomical defect. The blood work checks for functional defect. You can have a normal looking thyroid (no nodules, normal anatomy) but can be hypo or hyperthyroid on blood work (abnormal function).

Yes: Sestamibi scan should have been ordered if you had high serum calcium and high PTH and urine calcium is not low. It shows the abnormal parathyroid only 85 % of the time. The ultrasound is less likely to show an abnormal parathyroid and very dependent upon the person performing the ultrasound.