INTERRELATION BETWEEN PREOPERATIVE TESTS, INTRAOPERATIVE FINDINGS AND OUTCOMES OF 99M-TECHNETIUM-SESTAMIBI SCAN IN PRIMARY HYPERPARATHYROIDISM.

Context: Primary hyperparathyroidism is one of the most common endocrinological disorder and surgery of parathyroid glands is the main therapy of this disease. Minimally invasive surgery is getting more prominent in these days and its success in parathyroid surgery mostly depends on accuracy of the localization studies.

Objective: The aim of this study is to understand the relationship between preoperative biochemical tests, intraoperative findings and Technetium-99m-methoxyisobutylisonitrile (MIBI) scan results.

Design: Retrospective clinical study.

Subjects and methods: A total of 185 patients, who have been diagnosed with primary hyperparathyroidism (PHPT) and operated between January, 2010 and October, 2018, were included to the study. Patients with less than 6 months of follow up are excluded from the study.

Results: Patients were divided into two groups according to their scintigraphy results; with positive scintigraphy findings as group 1 (n:135) and negative scintigraphy findings as group 2 (n:50). Mean preoperative serum parathyroid hormone (PTH) values were significantly different between the two groups (p<0.02). Mean preoperative serum calcium, creatinine, magnesium, phosphorus, alkaline phosphatase, 25-OH Vitamin D3 levels of both groups were analyzed and there were no statistical differences between the two groups considering these parameters. Also, mean diameter and mean volume of parathyroid adenomas were significantly higher in group 1 (2.1±1.0 cm vs. 1.55±0.72 cm, respectively, p<0.0001; 2.66±5.35 cm³ vs. 1±1.9 cm³, respectively, p<0.0001). Optimal cut-off values of parathyroid adenoma diameter for MIBI scan positivity were 1.55 cm, parathyroid volume for MIBI scan positivity were 0.48 cm³, preoperative serum PTH for MIBI scan positivity were 124.5 ng/L.

Conclusions: Preoperative serum PTH levels, diameter and volume of adenomas might be helpful for the prediction of MIBI scan accuracy and possible need of another localization studies.