From the FDA Drug Label
Myxedema: Recommended starting dosage is 5 mcg daily. This may be increased by 5 to 10 mcg daily every 1 or 2 weeks. When 25 mcg daily is reached, dosage may be increased by 5 to 25 mcg every 1 or 2 weeks until a satisfactory therapeutic response is attained. Usual maintenance dose is 50 to 100 mcg daily
- The treatment protocol for patients with hypothyroidism using Cytomel (liothyronine) is to start with a dosage of 5 mcg daily, increasing by 5 to 10 mcg daily every 1 or 2 weeks.
- The dosage may be increased by 5 to 25 mcg every 1 or 2 weeks until a satisfactory therapeutic response is attained.
- The usual maintenance dose is 50 to 100 mcg daily 1
From the Research
Cytomel (liothyronine or T3) should be used as a second-line treatment for hypothyroidism, with the standard starting dose being 5-25 mcg daily, gradually increased by 5-25 mcg every 1-2 weeks until the patient reaches a maintenance dose of 25-75 mcg daily, as recommended by the most recent consensus statement 2.
Treatment Protocol
The treatment protocol for patients with hypothyroidism using Cytomel (liothyronine) involves:
- Starting with a low dose of 5-25 mcg daily, gradually increased by 5-25 mcg every 1-2 weeks until the patient reaches a maintenance dose of 25-75 mcg daily
- Dividing the medication into multiple doses throughout the day due to its short half-life of 1-2 days
- Laboratory monitoring with TSH and free T3 levels every 4-8 weeks during dose adjustments, then every 6-12 months once stabilized
Indications for Use
Cytomel is not typically used as first-line therapy for hypothyroidism; levothyroxine (Synthroid) remains the standard initial treatment. Cytomel is more commonly used in specific situations such as:
- T4 to T3 conversion disorders
- As adjunctive therapy with levothyroxine in patients with persistent symptoms despite normal TSH
- Temporarily when rapid onset of action is needed
Monitoring and Dose Adjustment
Patients should take Cytomel at the same time each day, preferably on an empty stomach, and should be monitored for signs of hyperthyroidism including palpitations, anxiety, insomnia, and weight loss, which may indicate the need for dose adjustment. According to a study published in 2020, reducing the LT4 dose by 25 mcg/day and adding 2.5-7.5 mcg liothyronine (LT3) once or twice a day is an appropriate starting point for combination therapy 3.
Key Considerations
It is essential to establish a diagnosis of overt hypothyroidism and optimize levothyroxine doses before considering Cytomel therapy, as recommended by the British Thyroid Association/Society for Endocrinology consensus statement 2. The decision to start treatment with Cytomel should be a shared decision between the patient and clinician, taking into account the potential benefits and risks of therapy.