NCT06647602

Thyroid Hormone Replacement After Radio Iodine: Value and Efficacy

• Status: Not Yet Recruiting
• Phase: —
• Study type: Observational
• Enrollment: 40 (estimated)
• Sponsor: University Medical Center Groningen · Academic / Other
• Sex: All
• Age: 18 Years – 75 Years
• Healthy volunteers: Not accepted

Summary

This study will be a multicentre prospective cohort study on TH-substitution after thyroid hormone withdrawal preceding radioiodine treatment.

Detailed description

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

Conditions

• Differentiated Thyroid Cancer
• Thyroid Cancer
• Levothyroxine
• Liothyronine
• Thyroid Hormones

Interventions

Type	Name	Description
DRUG	Euthyrox (levothyroxine)	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.
DRUG	Cytomel (liothyronine)	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.

Timeline

• Start date: 2026-09-01
• Primary completion: 2028-03-31
• Completion: 2028-12-31
• First posted: 2024-10-18
• Last updated: 2026-02-10

Locations

2 sites across 1 country: Netherlands

Regulatory

• FDA-regulated drug study