Risk factors for the development of hypocalcemia in pediatric patients after total thyroidectomy – A systematic review

Objectives Post-thyroidectomy hypocalcemia is a common complication that causes increased morbidity. This review aims to identify the factors that predict occurrence of hypocalcemia after total thyroidectomy in children and adolescents. Methods Comprehensive searches of English language pediatric (≤18 years of age) articles were performed in Medline, CINAHL, EMBASE, Web of Science and the Cochrane Library. Studies published between January 1, 1970 to August 20, 2020 regarding risk factors and strategies to prevent hypocalcemia were included if the study: 1. included only pediatric patients who were ≤18 years of age, 2. included only patients who had total, subtotal or completion thyroidectomy, 3. defined hypocalcemia as serum total calcium of <2.0 mmol/L (8 mg/dL) or ionized calcium of <1.0 mmol/L. The quality of included papers was assessed using the Newcastle-Ottawa scale. Results of all included studies were summarised. Meta-analyses were performed if appropriate. Results Five studies with a total of 477 patients between 0 and 18 years, who had total/subtotal/completion thyroidectomy, were included. Overall rates of transient hypocalcemia were higher than permanent hypocalcemia (transient n = 104, 22%; permanent n = 48, 10%). Two studies found intraoperative parathyroid hormone (PTH) useful in predicting hypocalcemia. While two single institution cohort studies reported that neck dissection, male sex and a lower Parathyroid Gland Remaining In Situ score were associated with hypocalcemia, two other studies, including one population-based cohort study, reported that age at surgery, patient sex, hospital volume, type of thyroid disease, number of identified parathyroid glands, parathyroid auto-transplantation, operation time, thyroid specimen weight, and lymph node dissection were not risk factors for hypocalcemia. Conclusion Intraoperative PTH may be useful in predicting hypocalcemia in children after total thyroidectomy. No consistent clinical risk factors or preventative methods were identified in the pediatric literature. High-quality pediatric research is urgently required to address this knowledge gap.