Higher Levothyroxine Requirements After Right-side Hemithyroidectomy

Higher Post-operative Levothyroxine Substitution Dose Needed in Right Compared to Left Lobe Hemithyroidectomy - a Retrospective Cohort Study

459 adult patients who received a hemithyroidectomy at the Department of General Surgery, Division of Endocrine Surgery and a follow-up visit (3-12 months post-surgery) at the thyroid outpatient clinic of the Department of Endocrinology and Metabolism, Medical University of Vienna between 1994 and 2018 were identified and investigated in this retrospective study. The aim of this study was to investigate whether patients post right side hemithyroidectomy require a higher mean levothyroxine dosage than patients after left lobe hemithyroidectomy as the right thyroid lobe is bigger than the left lobe. Further, we aimed at developing a better post-surgery thyroid dosage prediction model.

Study Overview

• Status: Completed
• Conditions: Hypothyroidism; Hemithyroidectomy
• Intervention / Treatment: Procedure: Hemithyroidectomy

Detailed Description

In most patients, the right lobe of the thyroid gland is larger than the left lobe. After a hemithyroidectomy, the remaining lobe grows by up to 30% to compensate for the loss. However, thyroxine replacement is still necessary for 22% to 60% of all patients. The aim of this study is to investigate whether a right-lobe hemithyroidectomy predisposes to a higher postoperative dose of levothyroxine.

Patients and Methods In a retrospective cohort study, 459 patients over the age of 18 years who underwent a hemithyroidectomy at the Department of General Surgery, Division of Endocrine Surgery and a follow-up (3-12 months post-surgery) visit at the thyroid outpatient clinic of the Department of Endocrinology and Metabolism between 1994 and 2018 were investigated. The study was approved by the local ethics committee and performed in accordance with the Declaration of Helsinki. The work has been reported in line with the STROCSS criteria. The patients were identified via data extraction from a university hospital-wide Research, Documentation and Analysis (RDA) database. In a second step, further information necessary for the analysis (ultrasound data on pre-surgery thyroid volume, pre-surgery TSH, side and date of hemithyroidectomy, surgery protocol, underlying thyroid disease, type and dosage of treatment, age, weight, height, thyrotropin (TSH), free T4 (fT4), free T3 (fT3)) were extracted from the internal electronic health record system. Patients who had either received radiation therapy had undergone previous thyroid surgery, surgery on the contralateral lobe, had pre-existing hypothyroidism, an autoimmune disease of the thyroid or were pregnant were excluded from the analysis. 33 patients were excluded due to additional surgery on the contralateral lobe resulting in a total of 426 patients. Pre-surgery ultrasound thyroid volume was calculated with the volumetric ellipsoid method (height × width × depth × correction factor 0.524).

• Study Type: Observational
• Enrollment (Actual): 459

Contacts and Locations

Study Locations

• Austria
  • Vienna, Austria, 1090
    • Medical University of Vienna

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 14 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

All patients who received a hemithyroidectomy at the Department of General Surgery, Division of Endocrine Surgery and a follow-up visit (3-12 months post-surgery) at the thyroid outpatient clinic of the Department of Endocrinology and Metabolism, Medical University of Vienna between 1994 and 2018 were identified and investigated in this retrospective study.

Description

Inclusion Criteria:

• 18 years
• Males and females
• St.p. hemithyroidectomy

Exclusion Criteria:

• Radiation therapy
• Pregnancy
• Previous thyroid surgery (e.g. nodule removal surgery)

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Retrospective

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Left-side hemithyroidectomy; Patients who received a hemithyroidectomy of the left thyroid lobe since 1994	Procedure: Hemithyroidectomy; We investigated patients who received a hemithyroidectomy at the Department of General Surgery, Division of Endocrine Surgery and a follow-up visit (3-12 months post-surgery) at the thyroid outpatient clinic of the Department of Endocrinology and Metabolism, Medical University of Vienna between 1994 and 2018.
Right-side hemithyroidectomy; Patients who received a hemithyroidectomy of the right thyroid lobe since 1994	Procedure: Hemithyroidectomy; We investigated patients who received a hemithyroidectomy at the Department of General Surgery, Division of Endocrine Surgery and a follow-up visit (3-12 months post-surgery) at the thyroid outpatient clinic of the Department of Endocrinology and Metabolism, Medical University of Vienna between 1994 and 2018.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Levothyroxine dosage	dosage of levothyroxine needed post surgery, compared between left and right side hemithyroidectomy	within 3 to 12 months post surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hypothyroidism	Incidence of hypothyroidism post surgery compared between left and right side hemithyroidectomy	within 3 to 12 months post surgery

Collaborators and Investigators

• Sponsor: Medical University of Vienna
• Investigators: Principal Investigator: Lana Kosi-Trebotic, Medical University of Vienna

Study record dates

Study Major Dates

• Study Start (Actual): May 5, 2020
• Primary Completion (Actual): June 12, 2020
• Study Completion (Actual): June 12, 2020

Study Registration Dates

• First Submitted: November 22, 2020
• First Submitted That Met QC Criteria: November 28, 2020
• First Posted (Actual): December 1, 2020

Study Record Updates

• Last Update Posted (Actual): December 1, 2020
• Last Update Submitted That Met QC Criteria: November 28, 2020
• Last Verified: November 1, 2020

More Information

Terms related to this study

• Keywords: Levothyroxine; Thyroid; Lobectomy; Hemithyroidectomy; Postoperative levothyroxine requirements
• Additional Relevant MeSH Terms: Endocrine System Diseases; Thyroid Diseases; Hypothyroidism
• Other Study ID Numbers: Hemithyreoidectomy

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No