Endocrine Abstracts

Iatrogenic remission of Primary Hyperparathyroidism (PHPT) is a rare phenomenon. We report a unique case of PHPT remission post FNAC. A 64-year-old gentleman was referred to endocrine clinic with incidental finding of hypercalcemia (Adjusted calcium 2.77 mmol/l and PTH 8 pmol/l). He was diagnosed with PHPT and was a candidate for surgical intervention. Sestamibi scan and ultrasound parathyroid were done to localise the adenoma. However, these two scans had conflicting results. Sestamibi scan showed two parathyroid adenomas postero-inferiorly, in contrast, ultrasound parathyroid showed thyroid nodule postero-inferiorly with benign features. Ultrasound guided FNAC of the probable thyroid nodule was done in the same setting by the radiologist, however the cytology was inconclusive. His calcium and PTH levels subsequently normalised (Adjusted calcium 2.5 mmol/l and PTH 3 pmol/l) for the first time in a year. The repeated Sestamibi scan 8 months post FNAC, surprisingly showed no scintigraphy evidence of parathyroid adenoma. Serial monitoring of calcium and PTH levels has been normal. In literature, 7 cases of PHPT remission post FNAC have been reported. Parathyroid adenoma could undergo haemorrhage or infarction post FNAC. Of these cases, three patients had recurrence of PHPT from 45 days to 4 months post procedure. Although this patient is currently in remission, he will require long term monitoring of bone profile due to the risk of recurrence. It is reported that FNAC of suspected parathyroid lesion has low sensitivity if it is done without PTH washout. Hence, in this unique instance of conflicting results of Sestamibi scan & Ultrasound Parathyroid, we suggest not to routinely perform FNAC for the diagnosis of PHPTH as patient may require long term monitoring post procedure. If FNAC is considered, then it should be done with PTH washout to improve sensitivity.