Intraoperative measures of parathyroid hormone (ioPTH) level show high accuracy in the prediction of outcomes from parathyroid surgery for primary hyperparathyroidism (pHPT), Swedish scientists have shown.
They suggest that overlooked mutations in the multiple endocrine neoplasia gene should be suspected in patients who have false-positive ioPTH findings and later go on to show surgical failure.
Reporting in the Archives of Surgery, the authors explain that "during surgery for sporadic pHPT, a sufficient decline in ioPTH findings has been shown to be associated with excellent early results."
They continue that, despite this, there is still debate surrounding the benefits of this measure of surgical outcome, as error rates of as much as 16% have been reported due to false-negative and false-positive results.
To investigate this issue further, Johan Westerdahl and Anders Bergenfelz, from Lund University, conducted a case study on 269 patients with sporadic pHPT who received first-time pHPT surgery with accompanying ioPTH measurement.
The patients were followed up for 10 years after surgery, with an average follow-up of 3.6 years.
The researchers found that the overall cure rate was 96%, and that ioPTH levels correctly predicted long-term outcomes of 248 (92%) patients.
However, Westerdahl and Bergenfelz discovered that six of the participants had a false-positive ioPTH result.
Moreover, five of these individuals with false-positive ioPTH findings had germline mutations in the MEN1 and MEN2 genes, which encode for multiple endocrine neoplasia. The remaining patient did not undergo genetic testing.
"Although somatic mutations in the MEN1 gene have been found in as many as nearly 20% of parathyroid adenomas, to our knowledge the association between unobserved germline MEN mutations and a false-positive ioPTH finding has never been presented before," the scientists state.
"Among the late surgical failures with false-positive ioPTH findings, a high incidence of overlooked MEN mutations can be suspected, and we suggest that genetic analyses in these patients are of great importance."