From the FDA Drug Label
The rapid onset and dissipation of action of liothyronine sodium (T3), as compared with levothyroxine sodium (T4), has led some clinicians to prefer its use in patients who might be more susceptible to the untoward effects of thyroid medication Liothyronine Sodium Tablets, USP may be used in preference to levothyroxine (T4) during radioisotope scanning procedures, since induction of hypothyroidism in those cases is more abrupt and can be of shorter duration. It may also be preferred when impairment of peripheral conversion of T4 to T3 is suspected.
Alternative thyroid medication: Liothyronine sodium (T3) may be considered as an alternative to levothyroxine (T4) in patients with no improvement on T4, particularly in cases where impairment of peripheral conversion of T4 to T3 is suspected 1.
From the Research
If levothyroxine (T4) isn't improving your symptoms, consider trying combination therapy with liothyronine (T3) added to your current levothyroxine, as this approach has been shown to be safe and effective in improving quality of life and cognition for some patients 2.
Key Considerations
- Before switching medications, ensure you've optimized your current levothyroxine regimen by taking it on an empty stomach, avoiding calcium/iron supplements within 4 hours, and checking for absorption issues.
- Verify that your dose is appropriate and that other conditions like adrenal problems, vitamin deficiencies, or autoimmune issues aren't causing persistent symptoms.
- Combination therapy with LT4+LT3 can restore euthyroidism while maintaining a normal serum TSH, and has not been associated with increased mortality or morbidity risk due to cardiovascular disease, atrial fibrillation, or fractures 3.
Alternative Options
- Natural desiccated thyroid (NDT) like Armour Thyroid or NP Thyroid may also be considered, but the consistency of T4 and T3 contents is monitored by the manufacturers only, and it remains outside formal FDA oversight 3.
- New slow-release LT3 formulations that provide stable serum T3 levels are being tested, and may offer an alternative option for patients who do not respond to traditional combination therapy 2.
Important Notes
- Any medication change should be done under medical supervision with regular thyroid function testing to monitor your response.
- The decision to start treatment with liothyronine should be a shared decision between patient and clinician, and individual clinicians should not feel obliged to start liothyronine or to continue liothyronine medication provided by other health care practitioners or accessed without medical advice, if they judge this not to be in the patient's best interest 4.