From the Guidelines
Levothyroxine is contraindicated in patients with untreated adrenal insufficiency, acute myocardial infarction not caused by hypothyroidism, uncorrected thyrotoxicosis, and known hypersensitivity to levothyroxine or its inactive ingredients. According to the U.S. Preventive Services Task Force recommendation statement published in the Annals of Internal Medicine in 2015 1, levothyroxine therapy can have adverse effects on bone mineral density and the cardiovascular system, such as angina, arrhythmia, and increased cardiac wall thickness.
Some key points to consider when prescribing levothyroxine include:
- Patients with cardiovascular disorders, including angina, coronary artery disease, and hypertension, should be treated with caution as levothyroxine can exacerbate these conditions 1.
- Elderly patients and those with long-standing hypothyroidism require careful dosing, typically starting at lower doses with gradual increases.
- Pregnant women may need dose adjustments as thyroid requirements often increase during pregnancy.
- Regular monitoring of thyroid function tests is essential when using this medication to ensure proper dosing and avoid complications.
It is also important to note that overtreatment with levothyroxine can lead to iatrogenic hypothyroidism, osteoporosis, fractures, abnormal cardiac output, or ventricular hypertrophy 1. Therefore, it is crucial to carefully evaluate the risks and benefits of levothyroxine therapy in each patient and to monitor them closely for potential adverse effects.
From the FDA Drug Label
Levothyroxine sodium tablets are contraindicated in patients with uncorrected adrenal insufficiency [see Warnings and Precautions Error! Hyperlink reference not valid.].
Levothyroxine contraindications include:
- Uncorrected adrenal insufficiency 2
No other direct contraindications are mentioned in the provided drug labels.
From the Research
Levothyroxine Contraindications
- Levothyroxine is contraindicated in patients with acute myocardial infarction (AMI) and uncontrolled adrenal insufficiency, as well as in patients with thyrotoxicosis or adrenal crisis 3.
- Patients with a history of hypothyroidism and those with high TSH levels may require careful management when initiating levothyroxine therapy, especially in the setting of AMI 4.
- Comorbidities such as gastroesophageal reflux disease, irritable bowel syndrome, lactose intolerance, and history of gastric bypass surgery or bowel resection may affect levothyroxine absorption 5.
- Concomitant medications, dietary supplements, and certain foods/beverages may also interfere with levothyroxine therapy, including:
- Prescription medications for gastrointestinal conditions
- Over-the-counter medications for gastrointestinal conditions
- Dietary supplements such as calcium and iron
- Foods/beverages high in fiber, iodine, or soy
- It is essential to consider these factors when initiating or adjusting levothyroxine therapy to ensure optimal treatment outcomes 5.
Special Considerations
- In patients with AMI, levothyroxine therapy may need to be initiated at a lower dose and gradually increased to avoid exacerbating cardiac disease 6, 4.
- Patients with hypothyroidism and AMI may require close monitoring of their thyroid function and cardiovascular status to minimize the risk of adverse outcomes 6, 4.
- Levothyroxine is the treatment of choice for hypothyroidism, but its use requires careful consideration of potential contraindications and interactions 7.