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Thyroid hormone and cardiovascular disease
M Gomberg-Maitland1, W H Frishman
1Department of Medicine, New York Hospital-Cornell Medical Center, NY, USA.
Insights
Thyroid hormone impacts the cardiovascular system, affecting heart function and blood vessels. Supplementation shows benefits only for documented hypothyroidism, not other systemic conditions like euthyroid sick syndrome.
Area of Science:
- Cardiology
- Endocrinology
Background:
- Thyroid hormone influences myocardial contractility, heart rate, and peripheral vascular resistance.
- Thyroid hormone deficiency can lead to cardiovascular disease and exacerbate existing conditions.
- Severe illness or surgery can cause 'euthyroid sick syndrome,' characterized by altered thyroid hormone levels.
Purpose of the Study:
- To explore the potential benefits of thyroid hormone supplementation in conditions associated with euthyroid sick syndrome.
- To evaluate thyroid hormone as a therapeutic option for cardiovascular conditions like heart failure and hyperlipidemia.
Main Methods:
- Review of existing literature on thyroid hormone's cardiovascular effects.
- Analysis of studies investigating thyroid hormone supplementation in various systemic illnesses and cardiovascular diseases.
Main Results:
- Thyroid hormone supplementation has shown promise for patients with documented hypothyroidism.
- Evidence supporting thyroid hormone supplementation for euthyroid sick syndrome or other systemic conditions is currently lacking.
- Thyroid hormone's cardiovascular effects make it a theoretical consideration for hemodynamic support.
Conclusions:
- Current evidence does not support thyroid hormone supplementation for systemic conditions beyond documented hypothyroidism.
- Further research is needed to clarify the role of thyroid hormone in managing euthyroid sick syndrome and related cardiovascular issues.
Abstract:
Thyroid hormone directly affects the heart and peripheral vascular system. The hormone can increase myocardial inotropy and heart rate and dilate peripheral arteries to increase cardiac output. An excessive deficiency of thyroid hormone can cause cardiovascular disease and aggravate many preexisting conditions. In severe systemic illness and after major surgical procedures changes in thyroid function can occur, leading to the "euthyroid sick syndrome." Patients will have normal or decreased levels of T4, decreased free and total T3, and usually normal levels of thyroid stimulating hormone. This syndrome may be an adaptive response to systemic illness that usually will revert to normal without hormone supplementation as the illness subsides. Recently, however, many investigators have explored the benefits of thyroid hormone supplementation in those diseases associated with euthyroid sick syndrome. Thyroid hormone's effects on the cardiovascular system make it an attractive therapy for those patients with impaired hemodynamics and low T3. Thyroid hormone has also been considered a treatment for patients with congestive heart failure, for patients undergoing cardiopulmonary bypass and heart transplantation, and for patients with hyperlipidemia. At present there is no evidence suggesting a favorable treatment outcome using thyroid hormone supplementation for any systemic condition except in those patients with documented hypothyroidism.