From the Guidelines
Thyroid hormone is crucial for maintaining normal bodily functions, and its imbalance can lead to significant morbidity and mortality, emphasizing the need for proper management and treatment. The importance of thyroid hormone is highlighted by its role in regulating metabolism, energy production, and growth throughout life 1. Produced by the thyroid gland, primarily as thyroxine (T4) and triiodothyronine (T3), these hormones control how quickly cells convert nutrients into energy. Thyroid hormone influences virtually every organ system, regulating heart rate, body temperature, digestive function, muscle control, brain development, and bone maintenance.
During childhood, adequate thyroid levels are critical for proper brain and physical development. In adults, thyroid hormone maintains proper metabolic rate, cardiovascular function, and cholesterol metabolism. Deficiency (hypothyroidism) can cause fatigue, weight gain, cold intolerance, and depression, while excess (hyperthyroidism) leads to weight loss, anxiety, heat intolerance, and rapid heartbeat. Treatment for hypothyroidism typically involves levothyroxine (synthetic T4) at individualized doses, usually taken daily on an empty stomach 1. Regular blood tests measuring thyroid-stimulating hormone (TSH) help determine proper dosing.
Key aspects of thyroid hormone management include:
- Screening for thyroid dysfunction, as recommended by the U.S. Preventive Services Task Force 1
- Treatment of hyperthyroidism with antithyroid medications or nonreversible thyroid ablation therapy 1
- Consideration of treatment for patients with a TSH level that is undetectable or less than 0.1 mIU/L, particularly those with overt Graves disease or nodular thyroid disease 1
- Importance of long-term randomized, blinded, controlled trials to provide direct evidence on the potential benefits of screening for thyroid dysfunction 1
From the FDA Drug Label
Thyroid hormones exert their physiologic actions through control of DNA transcription and protein synthesis. The physiological actions of thyroid hormones are produced predominantly by T3, the majority of which (approximately 80%) is derived from T4 by deiodination in peripheral tissues.
The importance of thyroid hormone is that it exerts physiologic actions through control of DNA transcription and protein synthesis, and its actions are produced predominantly by T3, which is derived from T4.
- Key functions: control of DNA transcription and protein synthesis
- Main action: produced predominantly by T3
- Source of T3: derived from T4 by deiodination in peripheral tissues 2
From the Research
Importance of Thyroid Hormone
The importance of thyroid hormone is evident in its role in regulating various bodily functions. Thyroid hormones play a crucial role in:
- Regulating metabolism and energy production
- Influencing growth and development
- Controlling heart rate and blood pressure
- Affecting mood and cognitive function
Consequences of Thyroid Hormone Imbalance
An imbalance of thyroid hormones can have significant consequences, including:
- Hyperthyroidism, which can cause cardiac arrhythmias, heart failure, osteoporosis, and adverse pregnancy outcomes 3
- Hypothyroidism, which can lead to fatigue, weight gain, and dry skin
- Thyrotoxicosis, which can cause anxiety, insomnia, palpitations, and unintentional weight loss 3
Treatment Options for Thyroid Hormone Imbalance
Treatment options for thyroid hormone imbalance include:
- Antithyroid medications, such as methimazole and propylthiouracil, for hyperthyroidism 4, 5
- Levothyroxine replacement therapy for hypothyroidism 6, 5
- Radioactive iodine ablation and surgical thyroidectomy for hyperthyroidism 4, 6, 3
- Combination therapy, such as levothyroxine combined with methimazole, for hyperthyroidism 7
Individualized Treatment Approach
An individualized treatment approach is recommended, taking into account the underlying pathology, age, sex, patient preference, and availability of expert thyroid surgical care 6, 3. This approach can help optimize treatment outcomes and minimize adverse effects.