Reference range of serum calcitonin in pediatric population.

BACKGROUND: Children belonging to the multiple endocrine neoplasia type 2 (MEN 2) pedigree and carrying germline RET mutations are candidates for prophylactic thyroidectomy, the timing of which is based on the mutation-associated risk and the calcitonin (CT) levels. DESIGN: The aim of this study was to establish the reference range for serum CT in a pediatric population. The study included 2740 subjects (1339 females and 1401 males) ranging in age from 1 day to 16 years and undergoing blood testing for any medical condition not affecting serum CT. RESULTS: Overall, serum CT was undetectable in 61.5% of the samples and detectable in 38.5%. Detectable samples were more frequent in the first 2 years of life. Thereafter, undetectable samples became more frequent, particularly in females. Mean serum CT concentrations were higher in the first year of life (9.81 ± 8.8 pg/mL; range, 2.0-48.9 pg/mL) and the second year of life (4.56 ± 2.64 pg/mL; range, 2.0-14.7 pg/mL). A significant decrease of serum CT levels was observed thereafter (P < .001), and starting from the third year of life serum CT levels were similar to those found in adults. No gender difference was found in any age group. Based on these results, age-specific CT reference ranges are needed in the pediatric population, and especially in the first 2 years of life. CONCLUSIONS: This is the first study defining the reference range for serum CT in the pediatric population and large enough to be statistically meaningful. Our proposal may facilitate the process of decision making when dealing with gene carriers of MEN 2.

Long-term efficacy of modified-release recombinant human thyrotropin augmented radioiodine therapy for benign multinodular goiter: results from a multicenter, international, randomized, placebo-controlled, dose-selection study.

BACKGROUND: Enhanced reduction of multinodular goiter (MNG) can be achieved by stimulation with recombinant human thyrotropin (rhTSH) before radioiodine ((131)I) therapy. The objective was to compare the long-term efficacy and safety of two low doses of modified release rhTSH (MRrhTSH) in combination with (131)I therapy. METHODS: In this phase II, single-blinded, placebo-controlled study, 95 patients (57.2 ± 9.6 years old, 85% women, 83% Caucasians) with MNG (median size 96.0 mL; range 31.9-242.2 mL) were randomized to receive placebo (n=32), 0.01 mg MRrhTSH (n=30), or 0.03 mg MRrhTSH (n=33) 24 hours before a calculated (131)I activity. Thyroid volume (TV) and smallest cross-sectional area of trachea (SCAT) were measured (by computed tomography scan) at baseline, six months, and 36 months. Thyroid function and quality of life (QoL) was evaluated at three-month and yearly intervals respectively. RESULTS: At six months, TV reduction was enhanced in the 0.03 mg MRrhTSH group (32.9% vs. 23.1% in the placebo group; p=0.03) but not in the 0.01 mg MRrhTSH group. At 36 months, the mean percent TV reduction from baseline was 44 ± 12.7% (SD) in the placebo group, 41 ± 21.0% in the 0.01 mg MRrhTSH group, and 53 ± 18.6% in the 0.03 mg MRrhTSH group, with no statistically significant differences among the groups, p=0.105. In the 0.03 mg MRrhTSH group, the subset of patients with basal (131)I uptake <20% had a 24% greater TV reduction at 36 months than the corresponding subset of patients in the placebo group (p=0.01). At 36 months, the largest relative increase in SCAT was observed in the 0.03 mg MRrhTSH group (13.4 ± 23.2%), but this was not statistically different from the increases observed in the placebo or the 0.01 mg MRrhTSH group (p=0.15). Goiter-related symptoms were reduced and QoL improved, without any enhanced benefit from using MRrhTSH. At three years, the prevalence of permanent hypothyroidism was 13%, 33%, and 45% in the placebo, 0.01 mg, and 0.03 mg MRrhTSH groups respectively. The overall safety profile of the study was favorable. CONCLUSIONS: When used as adjuvant to (131)I, enhanced MNG reduction could not be demonstrated with MRrhTSH doses ≤ 0.03 mg, indicating that the lower threshold for efficacy is around this level.