Methods
This retrospective multicenter study analyzes pediatric patients, operated over a 11 year period (January 2009 - December 2019) at several institutions (Division of Paediatric Surgery and Division of Endocrine Surgery at University of Pisa, Division of Pediatric Surgery at “Regina Margherita Hospital” in Turin, General Pediatric and Thoracic Surgery at Bambino Gesù Children׳s Hospital-Research Institute in Rome, Pediatric Surgery at Department of Woman and Child Health in Padua and the National Cancer Institute in Milan).
The variables taken into consideration are: gender, age, tumor size, type of surgery performed (total thyroidectomy - TT or hemithyroidectomy - HT), autotransplantation into the ipsilateral sternocleidomastoid muscle in case of incidental parathyroidectomy, lymph node dissection, histology (papillary carcinoma, diffuse sclerosing variant, follicular carcinoma, medullary carcinoma within genetic forms, such as MEN2A, MEN2B and FMTC). The age range at the operation was 4 - 18, with a mean age of 13.6 years. The exclusion criteria were: primitive hypoparathyroidism, low levels of vitamin D, low calcium level measured preoperatively, previous parathyroidectomy due to hyperparathyroidism or patients who received supplementary calcium treatment due to other causes. Follow-up after surgery consisted of measuring serum calcium levels by blood sampling. Post-operative hypocalcemia was defined as a serum calcium level of less than 8 mg/dl. The first measurement was made within 24 hours after the operation. A serum level check was repeated once a day in the three days following discharge. Postoperative parathyroid hormone (PTH) levels were determined in case of persistent low serum calcium levels 33-34. In patients with serum calcium levels <8 mg/dl with or without associated symptoms, intravenous or oral calcium was administered. In case of persistent hypocalcemia, subsequent serum calcium samples were drawn, with a frequency ranging from one per week to one per month4. Calcium supplementation doses were adjusted during follow-up according to symptoms and serum calcium levels 35. TtHP was considered when patients received calcium supplementation and/or had a normalization in PTH levels within 6 months after surgical treatment. PtHP was defined as the need for calcium supplementation with or without active Vitamin D even 6 months after surgery 7.