Fluctuation of Corrected Serum Calcium Levels Following Partial and Total Thyroidectomy

Objectives: To identify any fluctuation of corrected serum calcium levels and to determine the presence of sub-clinical hypocalcaemia following partial and total thyroidectomy with preservation of at least two parathyroid glands. Design: A prospective study. Setting: Tertiary Head & Neck referral unit. Patients: Eighty five patients undergoing partial or total thyroidectomy with or without laryngectomy from April 2003 to April 2009 were included in the study. Corrected serum calcium levels (CCSL) were noted preoperatively and postoperatively on day 1, day 7 and 6 months. Results: Forty six patients underwent hemi-thyroidectomy (HT), 29 underwent total thyroidectomy (TT) and 10 underwent total thyroidectomy with laryngectomy (TTL). Nine (19.56%) patients in the HT group, 6 (24.14%) in the TT group and 3 (30.0%) in the TTL group developed hypocalcaemia postoperatively which was most significant on 1st postoperative day. This improved by 7th postoperative day in each group when the change in calcium levels became statistically insignificant. Six patients (3 patients had HT, 2 had TT and 1 had TTL) developed sub-clinical mild hypocalcaemia which was persistent at 6 months follow-up. Conclusion: The most significant changes in corrected serum calcium levels occur within first 24 hours after thyroid surgery. Thereafter most patients return to normocalcaemia within a seven-day period. Despite preservation of parathyroid glands there is a subgroup of patients who develop sub-clinical hypocalcaemia which persists even at six months but does not require treatment.