The Impact of Subclinical Hypothyroidism on Cardiovascular System

January 17, 2020 updated by: Randa Mahrous Roushdy, Assiut University

The Impact of Subclinical Hypothyroidism on the Cardiovascular System

This research aims to evaluate the relation between SCH and cardiovascular System by assessment of lipid profile and carotid intima-media thickness (CIMT), as a marker of atherosclerosis, and endothelial function.

Study Overview

Status

Unknown

Conditions

Intervention / Treatment

Detailed Description

Subclinical hypothyroidism (SCH) is defined as a condition that characterized by elevated serum thyroid-stimulating hormone (TSH) concentrations (TSH: >4.5 mu/l), while circulating thyroxine (T4) and tri- iodothyronine (T3) levels remain within the normal range.

Depending on the extent of serum TSH elevation, SCH can be divided into Mild (where the concentration of serum TSH is in the range of 4.5-9 mU/l) Severe (TSH≥10 mU/l) SCH. Mild SCH constitutes ~75% of the total number of patients with SCH. The incidence of SCH varies between 5 and 10 % depending upon the gender, age, more frequent in women than in men, with increasing prevalence with advanced age in both sexes The consequences of SCH are variable at several levels and may depend on the duration and the degree of increasing level of the serum TSH. However, a number of important questions about SCH remain, including whether it increases cardiovascular (CVS) risk or not.

SCH has many causes the most common (60% to 80%) is chronic autoimmune thyroiditis associated with the presence of circulating anti-thyroid peroxidase antibodies(TPOAb) that are the most sensitive serological test for thyroid autoimmunity and/or antithyroglobulin Antibodies(TgAb).

The association between subclinical hypothyroidism (SCH) and cardiovascular disease has received increasing attention in recent years.

Thyroid hormones exert a direct effect on the heart and blood vessels. The deficit of these hormones leads to functional disorders of the Cardiovascular System (CVS) such as changes in cardiac frequency, cardiac output, left ventricular diastolic dysfunction, and reduced resting and exceptional systolic function.

Vascular abnormalities, such as increased vascular resistance, arterial stiffness, endothelial dysfunction, that is considered to be an early step in the development and progression of atherosclerosis.

The early changes in patients with SCH is alteration in lipid profile that could be a contributing factor for the risk of atherosclerosis, hyperlipidemia is one of the common causal factors of endothelial dysfunction.

Elevation of TSH has a positive correlation with serum total cholesterol (TC), triglycerides, LDL cholesterol (LDL-C), and a negative correlation to HDL cholesterol.

Some studies found significant lipid profile changes in patients with SCH, some others did not.

Atherosclerosis is a diffuse, degenerative disease of the arteries that results in the formation of porridge-like lipid deposit plaques in the great arterial wall, and accounts for the majority of cardiovascular disease incidence. Therefore, this association is the first to be assessed for the link between SCH and cardiovascular disease.

Progression of atherosclerosis features a chronic unresolved inflammatory response, leading to stenosis, embolization and thrombosis, since atherosclerosis is a chronic disease, to observe the whole pathogenesis in one single investigation would require a long time of study .Thus, endothelial dysfunction, as one of the earliest signs for atherosclerosis, could be most frequently observed in clinical investigation Assessment of endothelial dysfunction, being an early biomarker, is helpful in predicting cardiovascular risk by Carotid artery intima-media thickness (CIMT) measurement that has increasingly been used as a marker of atherosclerosis in many studies.

Evidence supporting the correlation between SCH and atherosclerosis has been accumulating:

The first study regarding the associated cardiovascular risk in patients with SCH was the long-time large cross-sectional Rotterdam study in the Netherlands, which showed an increased risk for atherosclerosis and prevalence of myocardial infarction among female patients with SCH aged >55 years. Velkoska and his colleagues who reported that SCH is associated with increase in CIMT and presence of carotid plaques independent of traditional atherosclerosis risk factors, Onder et al. who showed lack of a significant difference in CIMT between over and subclinical hypothyroid, indicating that the inflammation leading to increased CIMT starts in the subclinical phase .

Study Type

Observational

Enrollment (Anticipated)

100

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 55 years (ADULT)

Accepts Healthy Volunteers

N/A

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

patients who will be diagnosed as SCH, will present to Outpatient clinic of Assiut University hospitals

Description

Inclusion Criteria:

  • All healthy adult who will be diagnosed as SCH along with age ≥18 & gender-matched healthy relatives with normal thyroid function will be screened for evidence of high cardiovascular risk.

Exclusion Criteria:

  • Hypo or hyper-thyroidism, Diabetes, Hypertension, cardiovascular disease, smokers, pregnant and lactating women.

Patients who had been treated with anti-thyroid drugs, radio iodine therapy or thyroxin hormone supplement or who had under gone thyroid surgery, those with a history of thyroid cancer or head and neck malignancies.

Those with history of drug use such as Contraceptive pill, Anti-depressant drugs, Corticosteroids, Anti arrhythmic drugs.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Patients who will be diagnosed as Subclinical Hypothyroidism
50 pt who will be diagnosed as Subclinical Hypothyroidism by elevated level of TSH (TSH: >4.5 mu/l) and normal T4
Diagnostic test: Thyroid function
Thyroid function,Lipid Profile, systolic Blood pressure ,diastolic blood pressure .Body Mass Index ,CRP,Echocardiography،ECG, Ultrasonography of Carotid artery
Other Names:
  • Thyroid function,Lipid Profile, systolic Blood pressure ,diastolic blood pressure .Body Mass Index ,CRP,Echocardiography،ECG, Ultrasonography of Carotid artery
Patients with normal thyroid function
50 pt with normal thyroid function (TSH &T4)
Diagnostic test: Thyroid function
Thyroid function,Lipid Profile, systolic Blood pressure ,diastolic blood pressure .Body Mass Index ,CRP,Echocardiography،ECG, Ultrasonography of Carotid artery
Other Names:
  • Thyroid function,Lipid Profile, systolic Blood pressure ,diastolic blood pressure .Body Mass Index ,CRP,Echocardiography،ECG, Ultrasonography of Carotid artery

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Our data will reveale that SCH is associated with increase in CIMT and presence of carotid plaques,and these patients have an increased risk of cardiovascular disease compared with healthy patients.
Time Frame: Baseline
The study Will include 50 patients with newly diagnosed SCH, and 50 healthy controls. Body mass index (BMI), TSH, fT4, lipids, blood pressure, mean and maximum carotid intima-media thickness (CIMT) will be determined in all participants.
Baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Assiut University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (ANTICIPATED)

February 1, 2020

Primary Completion (ANTICIPATED)

May 1, 2021

Study Completion (ANTICIPATED)

June 1, 2021

Study Registration Dates

First Submitted

September 24, 2019

First Submitted That Met QC Criteria

January 17, 2020

First Posted (ACTUAL)

January 22, 2020

Study Record Updates

Last Update Posted (ACTUAL)

January 22, 2020

Last Update Submitted That Met QC Criteria

January 17, 2020

Last Verified

January 1, 2020

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Subclinical Hypothyroidism

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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