This study will be a multicentre prospective cohort study on TH-substitution after thyroid hormone withdrawal preceding radioiodine treatment.
While treatment with L-T4 after TH-withdrawal is widely used in DTC patients to suppress TSH and improve hypothyroid symptoms, the value of L-T3 addition in initiation of TH treatment has not been evaluated in this context. Lifelong monotherapy with L-T3 should not be preferred over L-T4 yet, short-term use of L-T3 to initiate TH-supplementation can be safely implemented. We hypothesize that initial treatment with L-T4+L-T3 combination treatment can have a more direct effect on TSH-levels and earlier relieve of hypothyroid symptoms resulting in a better QoL. We will conduct a prospective cohort study comparing the initiation of TH-supplementation after TH-withdrawal in two cohorts of DTC patients: patients receiving L-T4+LT3 with a gradually decrease of L-T3 dose in time, and patients receiving L-T4 only. We will compare potency to suppress TSH, effect on QoL and effects on thyroid- and cardiovascular parameters. Patients (18-75 years) diagnosed with high-risk DTC after TH-withdrawal will be eligible for inclusion. The primary objective is to compare the proportion of patients reaching target TSH-levels after two weeks of substitution with L-T3 or L-T4. Secondary objectives are to compare the effects of L-T4+L-T3 or L-T4 in the first 3 months of treatment on serum thyroid parameters TSH and Tg, quality of life, and cardiovascular parameters
Study Type
OBSERVATIONAL
Enrollment
40
Euthyrox (levothyroxine sodium tablets; L-T4) is a thyromimetic synthetic drug identical to T4. Patients will recieve levothyroxine (euthyrox) in a dose of 2 μg × kg body weight / day.
Cytomel (liothyronine sodium tablets; L-T3) is a thyromimetic synthetic drug identical to T3. The patients in this cohort recieve L-T4+L-T3 combination therapy. The L-T4 dose will be 2 μg × kg body weight / day, equal to the dose in the other interventional arm. L-T3 will be added twice daily from the first day of combination treatment, in dosages gradually decreasing from 25 ug 2/day to 5 ug 2/day over a time span of 3 weeks after which L-T3 is stopped.
University Medical Center Groningen (UMCG)
Groningen, Provincie Groningen, Netherlands
Radboud University Nijmegen
Nijmegen, Netherlands
TSH after two weeks of TH substitution
The percentage of patients reaching target TSH (\<0.5 mU/L) after two weeks of L-T3+L-T4 substitution compared to patients with L-T4-substitution.
Time frame: Before and after 2 weeks of TH-substitution
TSH (mU/L)
The % of decrease of serum thyroid parameters TSH after 1, 2, 4, 6, and 12 weeks of TH-substitution.
Time frame: Before and after 1, 2, 4, 6, and 12 weeks of TH-substitution.
Thyroglobulin (Tg; ng/mL)
The % of decrease of serum thyroid parameters Tg after 1, 2, 4, 6, and 12 weeks of TH-substitution. Tg is a precursor of T3 and T4 and is a measurement for remaining thyroid (cancer) cells. Tg-levels are affected by TSH and therefore, we expect by reducing TSH-levels to also reduce Tg levels. Consecutive Tg-measurements in this study act as a secondary measure for TH substitution. Since Tg-values between patients variable, we will use the % decrease instead of absolute values.
Time frame: Before and after 1, 2, 4, 6, and 12 weeks of TH-substitution
QoL in patients treated with L-T3 or L-T4
Quality of life will be assessed using standardized QoL questionnaires for thyroid- and thyroid cancer patient reported outcome. Our aim is to compare improvement of hypothyroid symptoms after initiation of therapy, and evaluate whether sings of hyperthyroidism and possible overtreatment are present. We will use the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 (core measure QoL questionnaire) in combination with the THYCA-QoL (additional thyroid cancer-specific part).
Time frame: Before and after 2, 6, and 12 weeks of TH-substitution
Heart rate (HR; bpm)
Cardiovascular parameters will be assessed during visits to the outpatient clinic before initiation of TH-substitution (during hypothyroidism) and after 6 weeks of TH-treatment. Patients will be compared intra- and interindividually.
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Time frame: Before and after 6 and 12 weeks of TH-substitution
Blood pressure (BP; mmHg)
Cardiovascular parameters will be assessed during visits to the outpatient clinic before initiation of TH-substitution (during hypothyroidism) and after 6 and 12 weeks of TH-treatment. Patients will be compared intra- and interindividually.
Time frame: Before and after 6 and 12 weeks of TH-substitution