IS DEVELOPMENT OF HYPOCALCAEMIA A SURROGATE MARKER FOR EXPERIENCE OF OPERATING SURGEON IN THYROIDECTOMIES? A SINGLE CENTRE RETROSPECTIVE ANALYSIS OVER 10 YEARS AND REVIEW OF LITERATURE ON HYPOCALCAEMIA FOLLOWING TOTAL THYROIDECTOMIES

Abstract

Introduction: Incidence of post thyroidectomy Hypocalcaemia ranges from 5.4% to 83%. We propose that the rate of change in serum calcium measurements (Calcium slope) in the first few hours after surgery is a good predictor of development of subsequent hypocalcaemia. We also analysed the incidence of hypocalcaemia over the years correlating with increasing experience of the surgeon.

Methods: Patients undergoing Thyroid Surgery from 2001-2012 under two thyroid surgeons were identified from a prospectively maintained database. Known Risk factors for hypocalcaemia were identified and recorded for each patient. Serum calcium was measured pre-operatively and post operatively at 6hrs, and 24hrs. Serum Calcium slope values (rate of fall of calcium levels) were calculated for time 0- 6hrs, and for time 0 -24hrs. Patients were divided into those who developed hypocalcaemia and those who did not, and risk factors compared between the two groups. Rates of hypocalcaemia were compared over 10 years as biannual cohorts and as 2 groups 2001 to 2006 Vs. 2007 to 2012 Results:

• From the 237 patients identified from database, 31.22% patients developed hypocalcaemia at 24hrs.
• There was a trend in fall in hypocalcaemia rates each year corresponding to the increased operative experience.
• Calcium slope levels at 6hrs are a good predictor of further hypocalcaemia.

Conclusion: There is a trend towards reduced rates of hypocalcaemia with increasing surgical experience, which may be another risk factor for hypocalcaemia. The magnitude of the early serum calcium slope may be a more useful means for identification of those at risk of developing hypocalcaemia after thyroidectomy.