Changes in TSH levels in athyreotic patients with differentiated thyroid cancer during levothyroxine therapy: influence on dose adjustments
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The aim of the study was to describe the spontaneous TSH level variations and levothyroxine dose adjustments in athyreotic patients with differentiated thyroid cancer (DTC) in real-life practice.
Patients with DTC were retrospectively evaluated at a tertiary referral center between October 2006 and November 2013. Hormone measurements (TSH and FT4 serum levels), L-T4 prescription information (dose per kg per day) and other medications were recorded at 1 month and 3, 12, 24, 36 and 48 months after primary treatment (surgery ± radioiodine therapy).
The cohort was composed of 452 patients; about 20% of patients with stable levothyroxine dose have clinically meaningful spontaneous TSH variations (defined as ΔTSH > 2 mcUI/mL) at yearly follow-up visit. Furthermore, about 25% of athyreotic DTC patients with stable dose have a ΔTSH > 1.5 mcUI/mL and about 40% a ΔTSH > 1 mcUI/mL during each follow-up visit. We further investigated whether this TSH variation would lead to subsequent dose changes. About 19.9–37.7% of DTC patients on stable LT4 dose on the previous visit had their levothyroxine dose reduced, while 7.8–14.9% increased due to TSH variations. We further evaluated the decision to change the dose in relation with the age-specific TSH range. Up to 77.2% of patients had their dose adjusted due to TSH falling below the age-specific range.
Spontaneous serum TSH variations determine levothyroxine replacement therapy in athyreotic patients with DTC, requiring multiple dose changes.
KeywordsThyroid cancer TSH variability Levothyroxine dose adjustment Real life Hypothyroidism
GG, VR and RF and contributed to this paper as part of their PhD studies in Biotechnologies and Clinical Medicine at the University of Rome, Sapienza. The study was supported by the Fondazione Umberto Di Mario ONLUS and Banca d’ Italia.
The study was supported by the Fondazione Umberto Di Mario ONLUS and Banca d’ Italia.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional ethics committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Thyroid cancer patient data were collected at our site, after obtaining the informed consent of the patients and approval of the local ethics committee.
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