What is the typical starting dose of Cytomel (liothyronine) for a patient?

Liothyronine (Cytomel) Dosing Guidelines

The typical starting dose of Cytomel (liothyronine) is 25 mcg daily for mild hypothyroidism, with gradual titration based on patient response and laboratory findings. 1

Initial Dosing Recommendations

• For mild hypothyroidism: Start with 25 mcg once daily, with increases of up to 25 mcg every 1-2 weeks as needed 1
• For severe hypothyroidism (myxedema): Start with 5 mcg daily, increasing by 5-10 mcg every 1-2 weeks; when 25 mcg daily is reached, may increase by 5-25 mcg every 1-2 weeks until therapeutic response is achieved 1
• For elderly patients or those with cardiovascular disease: Start with 5 mcg daily and increase only by 5 mcg increments at the recommended intervals due to increased risk of cardiac effects 1
• Maintenance dose typically ranges from 25-75 mcg daily for mild hypothyroidism and 50-100 mcg daily for myxedema 1

Administration Guidelines

• Liothyronine should be administered once daily 1
• The single daily dose can be taken at bedtime or with the main meal 1
• When switching from levothyroxine (T4) to liothyronine (T3), discontinue T4, start liothyronine at a low dose, and increase gradually according to patient response 1

Special Considerations

• Liothyronine has a rapid onset and offset of action compared to levothyroxine, which may lead to wider swings in serum T3 levels 1
• For patients previously on combination therapy, the therapeutic substitution ratio of liothyronine to levothyroxine is approximately 1:3 2
• When using liothyronine in combination with levothyroxine for patients who remain symptomatic on levothyroxine alone, reducing the levothyroxine dose by 25 mcg/day and adding 2.5-7.5 mcg liothyronine once or twice daily is an appropriate starting point 3
• Patients with coronary artery disease, elderly patients, or those with long-standing hypothyroidism should be started at lower doses with more gradual titration 1

Monitoring

• Monitor thyroid function tests regularly to ensure appropriate dosing
• Patients should be monitored for signs of hyperthyroidism, which may include tachycardia, anxiety, tremor, heat intolerance, and weight loss 1
• In patients with cardiovascular disease, monitor for exacerbation of angina or other cardiac symptoms 1

Important Precautions

• Liothyronine should not be used for weight loss in euthyroid patients as it is ineffective and potentially dangerous 1
• Severe and prolonged hypothyroidism can lead to decreased adrenocortical activity; supplemental adrenocortical steroids may be necessary in some cases 1
• Use with extreme caution in patients with cardiovascular disease, particularly coronary artery disease or in elderly patients 1
• Avoid overdosing, as thyrotoxicosis can occur with significant clinical consequences 4

Remember that liothyronine has a more rapid onset of action compared to levothyroxine, which requires careful dosing and monitoring to avoid adverse effects.