Does levothyroxine administration impact parathyroid localization?

Abstract

Background Proper localization is crucial in performing minimally invasive parathyroidectomy for primary hyperparathyroidism (PHPT). Ultrasonography (US) and Tc-99m sestamibi (MIBI) scintigraphy are common methods used for localization. As the appearance and activity of the thyroid gland may impact parathyroid localization, the purpose of this study was to determine how exogenous use of the thyroid hormone, levothyroxine (LT), affects parathyroid localization. Methods Adult patients with non-familial PHPT who underwent initial parathyroidectomy from 2000 to 2014 were retrospectively identified. Levothyroxine (+LT) and non-levothyroxine (-LT) patients were matched 1:3 based on age, gender, goiter status, and preoperative parathyroid hormone levels. Subgroup analysis was performed on patients previously treated with radioactive iodine and patients undergoing single adenoma resection. Results Of the 1,737 patients that met inclusion criteria, 286 were on LT at the time of their parathyroid localization scan. Use of LT not did impact the percentage of correct MIBI localization scans when compared to −LT patients (p=0.83). Interestingly, use of LT significantly hindered localization by US in comparison to the −LT group (48.4 vs 62.2%, p<0.01). When examining only patients where a single upper gland was removed, the +LT group was less likely to have a correct US compared to the −LT group (50 vs. 72.8%, p<0.01). However, there was no difference in US accuracy for patients who only had a single lower gland removed (p=0.51). Conclusions Exogenous levothyroxine is associated with impaired parathyroid localization with US but not MIBI. Surgeons should be aware of localization efficiency for this subset of patients in the era of personalized medicine and cost effectiveness.

Advances in the application of auxiliary imaging techniques in parathyroid diseases

“…Secondly, the gamma detector provides high-resolution radioactive images, allowing doctors to accurately locate and assess parathyroid tissue. Additionally, the real-time and non-invasive nature of 99mTc-MIBI imaging combined with a gamma detector allows for immediate imaging results without significant trauma to the patient’s body[ 13 ].…”