Introduction:
Hypoparathyroidism is characterised by symptoms of hypocalcaemia secondary to inadequate parathyroid hormone (PTH). Acquired hypoparathyroidism is most commonly seen after total thyroidectomy with or without dissection of the central neck nodes (CLND) (1). CLND is thought to confer higher rates of post operative hypoparathyroidism as the inferior parathyroids are at risk of devascularisation. Our aim was to determine institutional rates of temporary and permanent hypoparathyroidism in total thyroidectomy patients.
Methods:
Audit data for 275 consecutive patients undergoing total or completion thyroidectomy between November 2016 - May 2019 in the Department of Endocrine Surgery at Liverpool Hospital NSW, was retrospectively reviewed. Patients with parathyroid pathology to be treated concurrently were excluded. Serum PTH & corrected calcium levels were checked in recovery and on day 1 and 2 post operatively. Results were subdivided into 3 groups:
Normal (PTH in recovery >2.0 pmol/L ) [RR 2.0-6.0pmol/L]
Transient hypoparathyroidism (PTH Day 0 <2.0 pmol/L ; PTH Day 2 normal)
Hypoparathyroid (PTH Day 0 & 2 below normal).
The hypoparathyroid cohort had serial PTH and corrected calcium measured.
Clinicopathologic characteristics including extent of nodal surgery were compared between groups.
Results:
110 patients (40%) were hypoparathyroid at Day 0; one third (37 patients) had recovered by Day 2 and were considered transiently affected. 73/275 (26.5%) were discharged on treatment for hypoparathyroidism.
Follow-up data was available for 62/73 patients; 15 (5.7%) had persistent hypoparathyroidism over the following 3 months. 53% of these patients had undergone lymph nodes dissection compared to 19% in the normal group.
5/14 patients (35.7%) who had unilateral CLND and 2/3 who had bilateral CLND were hypoparathyroid at 3 months.
Conclusion:
Despite variable techniques employed for parathyroid preservation an overall low rate of chronic hypoparathyroidism is displayed. CLND is a strong risk factor for hypoparathyroidism.