Predictors of post-thyroidectomy hypocalcaemia: a systematic and narrative review

Abstract

<jats:title>Abstract</jats:title><jats:sec id="S0022215120001024_sec_a1" sec-type="other"><jats:title>Objective</jats:title><jats:p>Hypocalcaemia is the most common complication after total or completion thyroidectomy. This study assesses recent evidence on predictive factors for post-thyroidectomy hypocalcaemia in order to identify the patients affected and aid prevention.</jats:p></jats:sec><jats:sec id="S0022215120001024_sec_a2" sec-type="methods"><jats:title>Method</jats:title><jats:p>Two authors independently assessed articles and extracted data to provide a narrative synthesis. This study was an updated systematic search and narrative review regarding predictors of post-thyroidectomy hypocalcaemia using the Ovid Medline, Embase, Cochrane and Cinahl databases. Results were limited to papers published from January 2012 to August 2019.</jats:p></jats:sec><jats:sec id="S0022215120001024_sec_a3" sec-type="results"><jats:title>Results</jats:title><jats:p>Sixty-three observational studies with a total of 210 401 patients met the inclusion criteria. The median incidence was 27.5 per cent for transient biochemical hypocalcaemia, 12.5 per cent for symptomatic hypocalcaemia and 2.2 per cent for permanent hypocalcaemia. The most frequent statistically significant predictor of hypocalcaemia was peri-operative parathyroid hormone level. Symptomatic hypocalcaemia and permanent hypocalcaemia were seen more frequently in patients undergoing concomitant neck dissection.</jats:p></jats:sec><jats:sec id="S0022215120001024_sec_a4" sec-type="conclusions"><jats:title>Conclusion</jats:title><jats:p>Many factors have been studied for their link to post-thyroidectomy hypocalcaemia, and this study assesses the recent evidence presented in each case.</jats:p></jats:sec>

Risk Factors for Low Levels of Parathyroid Hormone after Surgery for Thyroid Cancer: A Single Center Study

“…Because postoperative calcium levels may be confounded by prophylactic calcium and calcitriol administration, or by low preoperative vitamin D levels, many groups preferred the measuring of intraoperative or postoperative intact PTH levels drawn at various time points in the early post-thyroidectomy period [ 10 , 14 , 20 ]. A recent statement on hypoparathyroidism of the American Thyroid Association found that the timing of PTH measurements in published studies has ranged from 10 min to 24 h post-thyroidectomy [ 14 ], and that a postoperative PTH level < 15 pg/mL is usually predictive of hypocalcemia [ 6 , 8 , 9 , 10 , 11 , 13 , 20 , 21 ]. However, serum PTH levels may remain stable within the first days after thyroidectomy and day 1 PTH levels may be accurate enough to predict hypocalcemia and direct the initiation of calcium supplementation [ 4 , 21 ].…”

“…Total thyroidectomy is one of the most frequently performed endocrine surgical procedures, and it can lead to serious complications, including temporary or permanent cordal palsy or postoperative bleeding, although hypoparathyroidism is the most frequent complication [ 4 , 5 , 6 ]. Hypoparathyroidism with hypocalcemia may affect 3–49% of patients undergoing thyroid surgery [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Many risk factors have been associated with an increased incidence of post-operative hypocalcemia.…”

“…Many risk factors have been associated with an increased incidence of post-operative hypocalcemia. Post-thyroidectomy hypocalcemia may arise from an incidental parathyroid removal, but the risk is also increased when a larger number of parathyroid glands are left in situ due to a compromised blood supply as a result of their dissection [ 6 , 9 , 13 ]; this risk could be further increased when a neck dissection is associated with a total thyroidectomy [ 6 , 8 , 9 , 10 , 11 , 13 ]. Parathyroid hormone (PTH) levels are the most frequently evaluated biochemical factor in the development of post-operative hypocalcemia, but the association between PTH levels and postoperative hypocalcemia has been reported with conflicting results [ 9 , 15 , 16 ].…”

“…Post-thyroidectomy hypocalcemia may arise from an incidental parathyroid removal, but the risk is also increased when a larger number of parathyroid glands are left in situ due to a compromised blood supply as a result of their dissection [ 6 , 9 , 13 ]; this risk could be further increased when a neck dissection is associated with a total thyroidectomy [ 6 , 8 , 9 , 10 , 11 , 13 ]. Parathyroid hormone (PTH) levels are the most frequently evaluated biochemical factor in the development of post-operative hypocalcemia, but the association between PTH levels and postoperative hypocalcemia has been reported with conflicting results [ 9 , 15 , 16 ]. Moreover, there is no consensus on the most useful predictive cut-off point for post-operative PTH levels and the appropriate time of PTH measurement after surgery: 1 h PTH level after skin closure may be predictive of postoperative hypocalcemia [ 6 , 8 , 9 , 10 , 11 , 13 ], while other studies suggested that a reduction in postoperative PTH of more than 44% [ 17 ] or more than 60% [ 18 ] is predictive of temporary biochemical hypocalcemia [ 7 , 14 , 19 ].…”

“…Parathyroid hormone (PTH) levels are the most frequently evaluated biochemical factor in the development of post-operative hypocalcemia, but the association between PTH levels and postoperative hypocalcemia has been reported with conflicting results [ 9 , 15 , 16 ]. Moreover, there is no consensus on the most useful predictive cut-off point for post-operative PTH levels and the appropriate time of PTH measurement after surgery: 1 h PTH level after skin closure may be predictive of postoperative hypocalcemia [ 6 , 8 , 9 , 10 , 11 , 13 ], while other studies suggested that a reduction in postoperative PTH of more than 44% [ 17 ] or more than 60% [ 18 ] is predictive of temporary biochemical hypocalcemia [ 7 , 14 , 19 ].…”