Fluctuation of Corrected Serum Calcium Levels Following Partial and Total Thyroidectomy

Vikas Malik,Prad Murthy,Glen J Watson,Chu Q Phua

doi:10.4236/ijcm.2011.24069

Abstract

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.

Highlights

Calcium regulation is critical for normal cell function, neural transmission, membrane stability, bone structure, blood coagulation, and intracellular signalling
The aim of this paper is to identify the fluctuation of Corrected serum calcium level (CSCL) over a six month period after thyroid surgery as well as to highlight the presence of sub-clinical hypocalcaemia despite preservation of parathyroid glands (PTG) and their blood supply
Despite there being no significant difference in CSCL over the medium term in each group, 3 patients (6.52%) who underwent hemi-thyroidectomy, 2 patients (6.89%) who underwent total thyroidectomy and 1 patient (10%) who had total thyroidectomy with laryngectomy had mild sub-clinical hypocalcaemia at 6 months postoperatively

Summary

Introduction

Calcium regulation is critical for normal cell function, neural transmission, membrane stability, bone structure, blood coagulation, and intracellular signalling. 99% of calcium is found in bone, and 1% is found in extra-cellular fluid Of this extra-cellular calcium, 50% is in the free (active) ionized form (1 mmol/L - 1.15 mmol/L), 40% is bound to protein (predominantly albumin), and 10% is complexed with anions (e.g. citrate). It is this 1% extra-cellular calcium that is essential for normal physiological function. Changes in the extra-cellular serum calcium levels after thyroid surgery leading to hypocalcaemia have frequently been reported [1,2,3,4,5]. The exact cause of transient and permanent hypocalcaemia post thyroidectomy is multi-factorial and has been linked to 1) hypoparathyroidism caused by iatrogenic damage to the parathyroid glands or their blood supply, 2) haemodilution, 3) hypoalbuminaemia, and 4) changes in peripheral sensitivity to parathyroid hormone

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