Intraoperative serum parathyroid hormone level is an indicator of hypocalcaemia in total thyroidectomy patients

Abstract

Postoperative hypocalcaemia is the most frequent and common complication after total thyroidectomy. It is necessary to diagnose or to predict hypocalcaemia immediately after total thyroidectomy for minimizing complications. A prospective observational study was carried out in the Department of Clinical Pathology in collaboration with Department of Microbiology & Immunology, Department of Surgery, Department of Otolaryngology, Bangabandhu Sheikh Mujib Medical University (BSMMU) and Department of Otolaryngology, Dhaka Medical College & Hospital (DMC&H), Dhaka, during the period of September 2010 to August 2011 to evaluate intraoperative (20 minutes after total thyroidectomy) parathyroid hormone (PTH) measurement as a predictor of post thyroidectomy hypocalcaemia. Total 65 patients were enrolled in this study those came for total thyroidectomy. Postoperative hypocalcaemia developed in 25 cases. Intraoperative PTH was assessed and significant correlation was found between intraoperative PTH level and development of hypocalcaemia. The sensitivity, specificity, accuracy, positive predictive value, negative predictive value of intraoperative serum PTH for prediction of post total thyroidectomy hypocalcaemia were 84.0%, 85.0%, 84.6%, 77.8%, and 89.5% respectively. Because of the high sensitivity, specificity and accuracy of intraoperative serum PTH of this study, the early prediction of hypocalcaemia could be made by single assay of intraoperative serum PTH level at 20 minutes after total thyroidectomy.

Predictors of post-thyroidectomy hypocalcaemia: a systematic and narrative review

“…Low post-operative PTH was found to have a statistically significant association with transient biochemical hypocalcaemia in 24 studies, 10–33 compared with 3 studies where there was not a statistically significant result 34–36 . Low intra-operative PTH levels and a larger differential PTH from the pre-operative to post-operative stage were also seen to have statistically significant associations in 2 studies 37,38 and 13 studies 10,12,14,15,22,23,27,29,31,36,39–41 , respectively. Pre-operative PTH showed a non-significant association with transient biochemical hypocalcaemia in the majority of studies.…”

“…Low post-operative calcium was the only other commonly assessed biochemical factor that showed a statistically significant positive association with transient biochemical hypocalcaemia in the majority of studies. 12,13,22–24,27,28,31,32,36,37,39,44,45 Positive associations were shown with post-operative calcitonin and post-operative albumin but in only one study. 18 Pre-operative vitamin D, magnesium, phosphate, creatinine, calcitonin and thyroid-stimulating hormone levels showed non-significant associations in the majority of studies where investigated.…”

“…Pre-operative PTH showed a non-significant association with transient biochemical hypocalcaemia in the majority of studies. 10,12,15,19,22,23,29,31,34–37,39,40,42,43…”

Parathyroid hormone assay in total thyroidectomy

“…17 8 where male was 35 (22%) and female 125 (78%), the mean age was 49.4 ± 14 years, ranged 18 to 86 years. Islam 9 reported mean age was 39 ± 13.18 with ranged 15 to 75 years and in his study also found female predominant; with male 22.5% and female 77.5%. In a review of the literature, there are different definitions of postoperative hypo-parathyroidism after thyroidectomy, mostly based on serum calcium levels.…”

“…Among them 16 hypocalcaemia were developed after 24 hours and 45 were developed after 48 hours of total thyroidectomy. Islam et al 9 in their study, the incidence of hypocalcaemia found 38.5% and post-operative hypocalcaemia found in 25 cases. Simon Grodski 8 found 26% hypocalcaemia in his study.…”