SHOULD INTRAOPERATIVE PARATHYROID HORMONE (IOPTH) BE MEASURED DURING MINIMALLY INVASIVE PARATHYROIDECTOMY ?
Minimally invasive parathyroidectomy (MIP) has become the procedure of choice in the treatment of primary hyperparathyroidism where a single adenoma can be localized preoperatively. Some surgeons recommend that measuring the drop in the levels of parathyroid hormone during surgery is a mandatory requirement for successful MIP in order to avoid missing multiple gland disease, or removing pathology that can mimic a parathyroid adenoma. However the test is very controversial and is not used in Australia. The problem is that it works best when needed least, that is in the 95% of cases where a solitary adenoma has already been resected, and is simply not all that accurate with multiple gland disease. It can also lead to a high rate of unnecessary conversion to an open parathyroidectomy. In an earlier study from the University of Sydney Endocrine Surgery Unit we performed “sham” IOPTH measurements on 100 consecutive patients undergoing MIP and showed that the use of IOPTH only changed the outcome 1% of the time, increasing the cure rate from 98% to 99%. However it came at a very significant cost with 9% of patients potentially being subject to an unnecessary open operation because of false negative results from the IOPTH tests. More recently we have reviewed over 1,000 MIP procedures performed in the unit without the use of IOPTH testing. The initial cure rate after the first operation was 98%, with all the remaining patients who then underwent a second operation being cured. Our preferred approach as the largest endocrine Surgical Unit in Australia therefore is that MIP is best performed without using IOPTH, accepting that up to 2% of patients will then require a second operation to deal with multiple gland disease or incorrect imaging leading to a missed adenoma.