Discussion
Hypocalcemia is one of the most frequent complications of thyroid surgery, due to decreasing PTH levels following surgery associated with intraoperative ischemia and/or reduction in volume of parathyroid glands or incidental parathyroidectomy 36. To date, few studies focused on hypocalcemia following thyroid surgery in children and adolescents, analyzing the possible predictive factors of this complication5, 36-42. In reported case-series TtHP incidence ranges from 13.6% to 34% 43-44 following total thyroidectomy in pediatric age. Nordenstrӧm et al. 45report that out of 274 patients, below 18 years of age undergoing thyroidectomy, 7.3% developed PtHP, while Klein Hesselink et al.30, analyzed 105 patients aged ≤18 years operated for differentiated thyroid cancer and reported that 23.8% of patients developed PtHP. Our data demonstrated that both TtHP and PtHP incidences are in line with current literature 30,43-46. Scholtz et al. 47 mention the existence of a female prevalence for postoperative hypoparathyroidism, linked to greater susceptibility to thyroid diseases. On the contrary, in our study, gender was not a determining factor in predicting the risk of developing these complications. De Groot JW et al. 48, confirmed by Kluijfhout WP 49 et al. and Moley JF et al50, showed that the smaller the age of the patients, the greater is the probability of developing postoperative hypoparathyroidism, due to the difficulty in identifying parathyroid glands during surgery or due to the greater fragility of the anatomical structures. The data we analyzed are in agreement with what was discussed above: patients with age ≤15 years have a significantly greater risk of developing TtHP; with regard to PtHP, data do not suggest any age-based difference. Younger children have a greater ability to recover from TtHP; in fact, in our series, two thirds of patients affected by postoperative hypocalcemia completely recovered. Patients between 16 and 18 years of age are less likely to recover, since all patients with TtHP developed PtHP. In our study, tumor size is associated with postoperative hypocalcemia: TtHP is more frequent in tumors ≥ 2 cm and size seems to be even more relevant for PtHP. TT behaves as a positive predictive factor for hypocalcemia with regards to low volume surgeons, as shown by Hauch et al. 51confirmed by Sosa 9. In our series, this complication occurred only in patients who underwent TT, we report no hypocalcemia related to HT; however Newman et al. 52 reported 9 cases (11%) of hypoparathyroidism out of 82 patients analyzed aged ≤21 years, who underwent lobectomy. In the present study, lymph node dissection seems to assume a fundamental role for PtHP; the reasons behind this might reside in the wider resection performed or the prolonged duration of surgery, which is in line with current literature53. With reference to the histotype as a predictor for the development of hypocalcemia in children, Scholz et al.47 identify PTC to be the most common, but in our experience this data does not reach significance. During surgery it is crucial to carry out a meticulous dissection aimed at preserving parathyroid glands and keeping their vascularization intact; a fundamental factor for post-operative normocalcemia is the preservation of at least three parathyroid glands in situ after surgery54. In order to prevent postoperative hypoparathyroidism, in case of inadvertent parathyroidectomy, parathyroid autotransplantation may be performed55,56, even though its effective utility has been questioned 57. We did not report any significant difference for what concerns parathyroids autotransplantation in TtHP and PtHP groups.