What is the optimal strategy to taper down Armor Thyroid (thyroid desiccated) 90 mg and combine with Levothyroxine (T4) in a patient with a low Thyroid-Stimulating Hormone (TSH) level of 0.078?

From the Guidelines

To address a TSH of 0.078 in a patient taking Armour Thyroid 90 mg, I recommend gradually transitioning to a combination therapy or to levothyroxine alone, as the current suppressed TSH indicates excessive thyroid hormone, which can lead to bone loss, atrial fibrillation, and other complications of hyperthyroidism. The patient's low TSH level suggests that they are at risk for hyperthyroidism-related complications, and adjusting their medication regimen is necessary to achieve a normal TSH range (typically 0.4-4.0 mIU/L) and prevent these complications 1.

Tapering Strategy

The tapering strategy should involve reducing the Armour Thyroid dose while introducing levothyroxine.

• First, reduce the Armour Thyroid to 60 mg daily for 2 weeks,
• then to 30 mg daily for another 2 weeks. During this taper, introduce levothyroxine 50 mcg daily when the patient reaches the 60 mg Armour dose. After completing the taper, adjust the levothyroxine dose based on follow-up TSH levels, typically checking 6-8 weeks after each dose change.

Rationale

This approach is supported by the US Preventive Services Task Force (USPSTF) recommendation that the principal treatment for hypothyroidism is oral T4 monotherapy (levothyroxine sodium) 1. Additionally, the USPSTF found that treatment is generally recommended for patients with a TSH level that is undetectable or less than 0.1 mIU/L, particularly those with overt Graves disease or nodular thyroid disease 1.

Monitoring and Adjustments

The patient's TSH levels should be closely monitored during the tapering process, and adjustments to the levothyroxine dose should be made as needed to achieve a normal TSH range. Some patients may benefit from continuing a small dose of Armour Thyroid alongside levothyroxine for symptom control, but this should be guided by both lab values and clinical response.

Key Considerations

• The serum TSH test is the primary screening test for thyroid dysfunction, and multiple tests should be done over a 3- to 6-month interval to confirm or rule out abnormal findings 1.
• The optimal screening interval for thyroid dysfunction is unknown, but follow-up testing of serum T4 levels in persons with persistently abnormal TSH levels can differentiate between subclinical and overt thyroid dysfunction 1.
• The goal of treatment is to achieve a TSH within normal range and prevent complications of hyperthyroidism, such as bone loss and atrial fibrillation.

From the Research

Tapering Down Armor Thyroid and Combining with Levothyroxine

To taper down Armor Thyroid (thyroid desiccated) 90 mg and combine with Levothyroxine (T4) in a patient with a low Thyroid-Stimulating Hormone (TSH) level of 0.078, consider the following:

• The optimal strategy is not explicitly stated in the provided studies, but a trial of combination therapy with LT4+LT3 can be considered for patients who have not benefited from LT4 monotherapy 2.
• 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 2.
• Desiccated thyroid extract (DTE) is a form of combination therapy with an LT4/LT3 ratio of ∼4:1, and the mean daily dose needed to normalize serum TSH contains ∼11 mcg T3 2.
• Patients who have undergone any weight or hormonal changes may require dose adjustments, and the majority of pregnant women require increased doses of levothyroxine 3.
• TSH goals are age-dependent, with a 97.5 percentile (upper limit of normal) of 3.6 mIU/L for patients under age 40, and 7.5 mIU/L for patients over age 80 4.
• Combined treatment with levothyroxine and liothyronine may be preferred in some hypothyroid patients who are dissatisfied with treatment, especially those with a polymorphism in type 2 deiodinase 4.

Key Considerations

• The diagnosis of subclinical hypothyroidism should be confirmed by repeat thyroid function tests ideally obtained at least 2 months later, as 62% of elevated TSH levels may revert to normal spontaneously 4.
• Treatment is not necessary unless the TSH exceeds 7.0-10 mIU/L, and treatment may be harmful in elderly patients with subclinical hypothyroidism 4.
• DTE therapy may be relevant for some hypothyroid patients, as it caused modest weight loss and nearly half of the study patients expressed preference for DTE over L-T4 5.
• Combined therapy with T4 and T3 or DTE leads to higher T3 and lower T4 levels compared to T4 monotherapy in hypothyroidism, but no significant effects on heart rate, lipid profile, or quality of life were noted 6.