Abstract | BACKGROUND: METHODS: RESULTS: While on vandetanib treatment, all 11 athyerotic patients exhibited significantly increased TSH levels. The baseline TSH level was 4.37 mclU/ml (0.08 - 23.30); in comparison, the first peak TSH concentration on vandetanib was 15.70 mclU/ml (12.50 - 137.00, p = 0.0010). The median time to reach the initial peak of elevated TSH was 1.8 months (0.3 - 9.3). Free T4 levels remained within the normal reference range. An increase from a baseline LT dose of 91 mcg/m(2)/day (±24) to 116 mcg/m(2)/day (±24) was required in order to resume normative TSH levels (p = 0.00005), equal to an increase of 36.6% (±16.56) in the dosage of LT in mcg/day. For the 2 patients with intact thyroid glands, free T4 and TSH remained normal over a combined 6 patient years of follow up. 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.
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Authors | Maya Lodish, Alexandra Gkourogianni, Ethan Bornstein, Ninet Sinaii, Elizabeth Fox, Meredith Chuk, Leigh Marcus, Srivandana Akshintala, Frank Balis, Brigitte Widemann, Constantine A Stratakis |
Journal | International journal of pediatric endocrinology
(Int J Pediatr Endocrinol)
Vol. 2015
Issue 1
Pg. 3
( 2015)
ISSN: 1687-9848 [Print] England |
PMID | 25972901
(Publication Type: Journal Article)
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