Levothyroxine Replacement With Liquid Gel Capsules vs Tablets Post-thyroidectomy

Levothyroxine Replacement With Liquid Gel Capsules or Tablets in Post-thyroidectomy Stage in Low Risk Differentiated Thyroid Cancer Patients

In some patients, levothyroxine liquid gel capsules may demonstrate superior absorption than the tablet option. Impaired absorption of thyroid hormone directly correlates to higher and more unpredictable TSH (thyroid stimulating hormone) levels. The investigators therefore hypothesize that following thyroidectomy for Stage I/II differentiated thyroid cancer the gel capsule levothyroxine formulation will provide more predictable TSH results and in turn require fewer dose adjustments to achieve optimal hormone levels in the postoperative period. The aim of this investigation is to compare the use of levothyroxine in liquid gel capsules to tablet form for TSH suppression following thyroidectomy for presumed stage I/II differentiated thyroid cancer.

Ten patients will be randomized prior to surgery to receive levothyroxine in tablet form and ten patients will be randomized to receive in gel capsule form. Both forms will be encapsulated in order to allow double-blinding of the study. The postoperative goal TSH will be between 0.1 and 0.5 mU/L (milli units per litre) in both arms. Patients will be seen at weeks 6, 12 and 18 postoperatively and have TSH and Free T4 measured. The primary outcome is the number of patients at each visit that are at goal range TSH. A secondary analysis will compare the dose changes required between the two groups in order to achieve goal TSH. Another secondary analysis will investigate the patients' quality of life. Two different surveys (see secondary outcomes below) will be performed at both study entry and completion to compare the two groups.

Patients post-thyroidectomy will receive either levothyroxine in tablet form or in gelcaps. Initial dose 1.5-1.8 mcg per kg, orally and daily

The target TSH (Thyroid stimulating hormone) range will be 0.1 to 0.5 mU/L. The number of patients in each arm (gelcaps or tablets) who are in this range at the completion of the study (18 weeks) will be assessed and the data compared at completion of the study.

The number of dose adjustments required to attain TSH target range for each formulation will be tabulated and the data compared at the end of the study

Patients will be administered survey (Thyroid-Dependent Quality of Life ) to assess their quality of life (at the beginning of the study and again at study completion). The results of these scores will be tabulated and compared between the two arms. Possible score range from 0 to 450; lower score means improved quality of life.

The Thyroid Treatment Satisfaction Questionnaire Measures the treatment satisfaction. Possible measure 0 to 42; Higher the score, better the outcome (more satisfied the patient)

Inclusion Criteria: Age > 18 years Presumed AJCC (American Joint Committee on Cancer) tumor Stage I or II Planned total or near-total thyroidectomy Planned goal TSH suppression 0.1-0.5 mU/L for at least 18 weeks postoperatively Normal serum TSH within 12 months preceding surgery Exclusion Criteria: AJCC Stage III or greater Undifferentiated, Anaplastic or Medullary Thyroid Cancer Planned postoperative TSH goal other than 0.1-0.5 mU/L History of gastrointestinal malabsorption or gastric bypass surgery Pregnancy Use of medications that alter the absorption or metabolism of levothyroxine Prior use of levothyroxine

Vita R, Fallahi P, Antonelli A, Benvenga S. The administration of L-thyroxine as soft gel capsule or liquid solution. Expert Opin Drug Deliv. 2014 Jul;11(7):1103-11. doi: 10.1517/17425247.2014.918101. Epub 2014 Jun 4.

McMillan CV, Bradley C, Woodcock A, Razvi S, Weaver JU. Design of new questionnaires to measure quality of life and treatment satisfaction in hypothyroidism. Thyroid. 2004 Nov;14(11):916-25. doi: 10.1089/thy.2004.14.916.