Determination of calcium and parathyroid hormone levels following hemithyroidectomy

Abstract

Background and objective: Hypocalcemia is one of the main complications of thyroid surgery. We hypothesized that hemithyroidectomy may have an impact on serum parathyroid hormone (PTH) and calcium levels despite only one thyroid lobe is manipulated. The objective of this study was to analyze changes in serum PTH and calcium levels following hemithyroidectomy.

Methods: This is a prospective study of 53 patients who underwent thyroid lobectomy. The serum PTH level was determined in the preoperative period, 15 min after extraction of the surgical specimen, and 24 h and 3 weeks after surgery. Serum ionized calcium was also measured in the preoperative period and at 6 h, 24 h and 3 weeks after surgery. We assessed the postoperative calcium value and its relationship with the extent of fall in PTH levels in the postoperative period.

Results: None of the patients had the postoperative serum ionised calcium level less than 4 mg/dl. The decrease in postoperative calcium was statistically significant at 6 and 24 h after surgery; there was no difference at 3 weeks post-surgery. The change in post-operative serum PTH levels followed a similar trend to postoperative serum calcium levels.

Conclusions: Although serum calcium level decreased after a lobectomy, it always remained above 4 mg/dl. We conclude that hypocalcaemia is rare following hemithyroidectomy.

Keywords: Hemithyroidectomy; Hypocalcemia; Intraoperative PTH.

Fig. 1

Longitudinal profiles in calcium and PTH

Fig. 2

Pearson’s correlation for percentage decrease in PTH and calcemia obtained 6 h after the intervention

Fig. 3

Parathyroid glands identified in surgery and their characteristics