Hypocalcaemia from hypoparathyroidism post total thyroidectomy (TT) is a burdensome complication. Parathyroid auto fluorescence and ICG imaging is a valuable operative innovation for parathyroid identification and preservation but fails to demonstrate quantitative flow. This study explores the impact of intraoperative hypotension on post operative parathyroid hormone (PTH) levels.

Single centre retrospective study. PTH Day 1 ≥ or < 1.2pmol/L designated patient groups. Intraoperative cross-group differences analysed as Wilcoxon and Chi-squared: lowest mean arterial pressure (MAP) and systolic blood pressure (SBP), difference admission SBP to intraoperative SBP (∆ SBP), operative duration and blood loss. Pearson and Spearman Rank correlation for PTH to age, gender, BMI, hypertension, number of glands identified, gland weight and intraoperative parameters.

43 patients (84% female; age 50.7 yrs SD = 13.2) underwent TT. 25 had thyroiditis (58%) and median gland weight of 63g (10.2-252g). An average 2.49 parathyroid glands were identified (range 0-4). 10 patients (23%) had a PTH-D1 <1.2pmol/l and 20 (46.5%) low PTH <3pmol/l. No patients had permanent hypoparathyroidism. PTH <1.2pmol/l was not correlated to lowest intraoperative SBP (p = 0.96) or the ∆SBP (p = 0.66). Lower PTH values are more frequently recorded in patients with intraoperative hypotension (p=0.47). 15 patients had a MAP <60mmhg, but these patients did not have significantly lower PTH (4.43 vs 3.03pmol/l). Cross-group difference analysis identified lower PTH for increased number of glands identified (p=0.075).

This study has not shown intraoperative hypotension to significantly impact post operative PTH measurements albeit a trend between hypotension and lower post operative PTH.