Bedeutung der intraoperativen Parathormonbestimmung für Reoperationen wegen Hyperparathyreoidismus

Patients with Hyperparathyroidism awaiting secondary procedure after failed initial operations are facing increased morbidity. Preoperative localisation of missing adenomas can reduce the extend and thus morbidity of the operation. The potential of intraoperative parathyroid hormone assaying to complete localisation workup and the prognostic value for postoperative normocalcaemia has not yet been examined and was the aim of this prospective observational clinical trial. Patients and Methods A consecutive series of 20 patients with reoperations for persistent or recurrent Hyperparathyroidism (primary and secondary) was studied. All patients underwent preoperative MRI, a Technetium 99m SestaMIBI scan, cervical Ultrasound and selective venous catheterisation for PTH sampling. Intraoperative approach included PTH sampling from the internal jugular veins and determination of post excisional systemic PTH levels using Quick-IntraOperative™ Intact PTH Assay by Nichols Institute Diagnostics. Follow up of patients took place at least six months after surgery. Results 18 out of 20 patients were followed up six months after surgery. 13 were cured, five patients were still hypercalcemic. In 15 of the 18 Patients (83.3 %) postoperative normo- or hypercalcaemia was predicted by obtaining postexcisional PTH levels. The accuracy of this test was 80.8 %. Accuracy of Technetium 99m SestaMIBI scans was 79 %. There were no false positive test results. Only SestaMIBI scans were able to detect all ectopic mediastinal glands in this survey. Four times SestaMIBI scans did not indicate an enlarged parathyroid gland. In all four cases bilateral disease was found during the operation. MRI, with an accuracy of 70 %, and Ultrasound of the neck, with an accuracy of 69 %, were of less diagnostic value in this survey. MRI was able to detect four out of six ectopic mediastinal parathyroid glands and could thus be relied upon to verify inconclusive previous test results. Intraoperative venous sampling from the internal jugular veins was found to be more helpful than preoperative selective venous catheterization with an accuracy of 89,6 % vs. 65,4 %. Conclusion 1 Neck exploration should begin at the site of an enlarged parathyroid gland shown by the SestaMIBI scan. If the Technetium 99m SestaMIBI scan does not reveal an enlarged parathyroid gland it is safe to assume bilateral disease. 2 If available intraoperative PTH sampling from the internal jugular veins should be obtained. Surgery should start on the side where this test indicates an enlarged parathyroid gland. 3 Post excisional systemic PTH levels should be obtained during surgery. If systemic PTH levels show a 50 % decline five Minutes or a 60 % decline 15 minutes after excision of an enlarged parathyroid gland cure of the patient can be assumed and the operation can be ended. If post excisional PTH levels fall within the range of physiologic PTH values, i.e. beneath 65 pg/l, cure can also be assumed and surgery can be ended. If no such a decline of PTH levels can be found one should assume another enlarged parathyroid and neck exploration should continue.