Recombinant thyrotropin use in children and adolescents with differentiated thyroid cancer: a multicenter retrospective study.

Context: Although recombinant human TSH (rhTSH) is widely used in differentiated thyroid cancer (DTC) to aid diagnostic follow-up procedures and radioiodine thyroid remnant ablation, almost all clinical investigation was in adults.

Objective: The aim of this study was to characterize rhTSH clinical safety and peak TSH response in DTC patients 18 yr old or younger.

Design And Setting: We conducted a retrospective study involving 23 tertiary referral centers in 12 European, Asian, and Oceanian countries.

Patients: One hundred DTC patients (69% female, 31% male, 84% papillary, 61% N1, 18% M1) ages 4.9-18 yr at first rhTSH administration were studied.

Interventions: A total of 181 rhTSH courses were administered (range, one to eight per patient; 42% of patients received two or more courses), 92% using the approved adult regimen (one 0.9 mg im injection daily on two consecutive days), 34% including thyroid hormone withdrawal for less than 7 d ("mini-THW").

Main Outcome Measures: Clinical adverse event (AE) incidence, type, and severity, and peak post-rhTSH serum TSH concentrations were assessed.

Results: No clinical AEs occurred in 88% of rhTSH courses. Most common clinical AEs were nausea (5% of courses) and vomiting (3%). Multiple or severe AEs were rare (0.6% and 2.8% of courses, respectively); serious AEs were absent. Peak TSH concentration post-rhTSH exceeded 25 mU/liter in approximately 98% of courses. In logistic regression analyses, the rhTSH regimen, "mini-THW," peak TSH concentration, body mass index (BMI), or peak TSH concentration/unit of BMI were not associated with clinical AE occurrence. In analyses of covariance, higher BMI was associated with lower peak TSH concentrations.

Conclusions: rhTSH was clinically well tolerated in pediatric DTC patients although courses preponderantly comprised the adult regimen, and repeated courses were frequent. Both the adult and reduced-dose regimens almost always sufficiently elevate TSH in children and adolescents.