From the FDA Drug Label
• Uncorrected adrenal insufficiency. The thyroid hormone levothyroxine is contraindicated in patients with uncorrected adrenal insufficiency 1.
From the Research
Thyroid hormone therapy is contraindicated in patients with untreated adrenal insufficiency, acute myocardial infarction (heart attack), and thyrotoxicosis (excessive thyroid hormone levels). When considering the management of hypothyroidism in patients with acute myocardial infarction, it is crucial to weigh the benefits of thyroid hormone replacement against the potential risks, as evidenced by a study published in 2020 2. This study highlighted that the management of hypothyroidism in the setting of acute myocardial infarction is largely guided by the patient's history of hypothyroidism and the degree of TSH elevation. However, the clinical effect of correcting hypothyroidism in this setting requires further evaluation.
Key considerations include:
- Untreated adrenal insufficiency: Thyroid hormone increases metabolic rate and can precipitate an adrenal crisis in these patients; adrenal function must be normalized before initiating thyroid replacement.
- Acute myocardial infarction: The increased cardiac demands from thyroid hormone can extend the infarct and worsen outcomes.
- Coronary artery disease: Thyroid hormone should be used with extreme caution as it can worsen angina or precipitate cardiac events by increasing heart rate and cardiac workload.
- Elderly patients and those with cardiovascular disease: Thyroid hormone should be used cautiously, starting with lower doses and gradually titrating upward.
In high-risk patients, when thyroid hormone is necessary, clinicians should start with lower doses (such as 25 mcg of levothyroxine) and increase gradually while monitoring for adverse cardiovascular effects, as suggested by various studies including one from 2002 3 and another from 2012 4. These studies, although not directly answering the question, provide insight into the complex relationship between thyroid hormones and cardiovascular health, emphasizing the need for cautious management.
Ultimately, the decision to initiate thyroid hormone therapy in patients with specific conditions should be made on a case-by-case basis, prioritizing the patient's overall morbidity, mortality, and quality of life.