Effects of Levothyroxine on Endothelial Function of Patients With Subclinical Hypothyroidism

Overview

Hypothyroidism is risk factor in atherosclerotic cardiovascular diseases, but there is a controversy in effect of subclinical hypothyroidism on cardiovascular diseases. We aim to estimate the relation between subclinical hypothyroidism and endothelial dysfunction and the effects of levothyroxine therapy on it. Patients with confirmed subclinical hypothyroidism by lab results will be randomized to two groups of treatment with one daily dose of 100 mg Levothyroxine or placebo. The flow-mediated dilation and intima media thickness are evaluated before and after the study.

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: Triple (Participant, Investigator, Outcomes Assessor)
  • Study Primary Completion Date: February 2014

Interventions

  • Drug: Levothyroxine
  • Drug: Placebo

Arms, Groups and Cohorts

  • Experimental: Levothyroxin
    • In the treatment group, daily doses of 100 mg of Levothyroxine will be administered every morning, half an hour before breakfast.
  • Placebo Comparator: Placebo
    • In the placebo group treatment regimen and advices are identical to that of the treatment group, except for using a pharmacologically neutral agent, with complete resemblance to the real treatment.

Clinical Trial Outcome Measures

Primary Measures

  • Change from baseline flow-mediated dilation at 2 months
    • Time Frame: At baseline and then 2 months after treatment
    • Flow-mediated dilation will be assessed using standard method with a radiologist unaware to the study arms at baseline and then 2 months after treatment.
  • Change from baseline intima-media thickness at 2 months
    • Time Frame: At baseline and then 2 months after treatment
    • Intima-media thickness will be assessed using standard method with a radiologist unaware to the study arms at baseline and then 2 months after treatment.

Participating in This Clinical Trial

Inclusion Criteria

  • age 18 to 65 – confirmed subclinical hypothyroidism Exclusion Criteria:

  • receiving of other treatments for hypothyroidism – patients with other major medical disorders – smoking – hyperlipidemia – obesity

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: 65 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Isfahan University of Medical Sciences
  • Provider of Information About this Clinical Study
    • Principal Investigator: Nasmi Niknam, Dr. – Isfahan University of Medical Sciences
  • Overall Official(s)
    • Nasmi Niknam, M.D., Principal Investigator, Isfahan University of Medical Sciences

References

Walsh JP, Bremner AP, Bulsara MK, O'Leary P, Leedman PJ, Feddema P, Michelangeli V. Subclinical thyroid dysfunction as a risk factor for cardiovascular disease. Arch Intern Med. 2005 Nov 28;165(21):2467-72. doi: 10.1001/archinte.165.21.2467.

Alibaz Oner F, Yurdakul S, Oner E, Kubat Uzum A, Erguney M. Evaluation of the effect of L-thyroxin therapy on endothelial functions in patients with subclinical hypothyroidism. Endocrine. 2011 Oct;40(2):280-4. doi: 10.1007/s12020-011-9465-2. Epub 2011 Apr 20.

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