Patterns of thyroid hormone levels in pediatric medullary thyroid carcinoma patients on vandetanib therapy

Conclusions: In our cohort of pediatric MTC patients, athyreotic patients with preexisting hypothyroidism developed increased TSH and reduced free T4 during the first few months of treatment with vandetanib, necessitating an increase in LT dosage. Additional patients with normal thyroid function before treatment and intact glands (n = 2) maintained normal thyroid function tests during treatment. Elevated TSH in athyreotic patients may be due to an indirect effect of vandetanib on the metabolism of thyroid hormone, or to altered TSH sensitivity at the pituitary. Proper recognition and management of abnormal thyroid hormone levels is critical in growing children on TKIs.Trial registration: ClinicalTrials.gov Identifier: NCT00514046
Source: International Journal of Pediatric Endocrinology - Category: Endocrinology Authors: Source Type: research