What is the diagnosis for a 36-year-old female with severely elevated Thyroid-Stimulating Hormone (TSH) levels, indicating hypothyroidism?

From the Guidelines

This patient has severe hypothyroidism as indicated by the markedly elevated TSH level of 13,163 mUI/L, and treatment should begin immediately with levothyroxine (T4) at a dose of 1.6 mcg/kg/day, which for most adults is approximately 100-125 mcg daily, as recommended by the USPSTF 1. For this 36-year-old patient, assuming average weight, starting with levothyroxine 100 mcg daily taken in the morning on an empty stomach, 30-60 minutes before breakfast, would be appropriate. The medication should be taken with water only, avoiding calcium, iron supplements, and certain foods which can interfere with absorption. TSH and free T4 levels should be checked after 6-8 weeks of therapy to assess response and adjust dosing as needed. The goal is to normalize TSH (typically to 0.5-2.5 mUI/L). Given the extremely high TSH level, this patient should also be evaluated for symptoms of myxedema (severe hypothyroidism) including profound fatigue, cold intolerance, bradycardia, and mental status changes. Additional testing for thyroid antibodies would help determine if this is autoimmune thyroiditis (Hashimoto's), the most common cause of primary hypothyroidism, as stated in the USPSTF recommendation statement 1. Once stabilized, the patient will likely require lifelong thyroid hormone replacement with periodic monitoring of thyroid function tests. Some key points to consider in the management of this patient include:

• The principal treatment for hypothyroidism is oral T4 monotherapy (levothyroxine sodium) 1.
• The optimal screening interval for thyroid dysfunction is unknown, but multiple tests should be done over a 3- to 6-month interval to confirm or rule out abnormal findings 1.
• The effects of treatment of thyroid dysfunction on important clinical outcomes may be independent of any known intermediate outcomes, and long-term randomized, blinded, controlled trials of screening for thyroid dysfunction would provide the most direct evidence on any potential benefits of this widespread practice 1.

From the FDA Drug Label

Thyroid hormone drugs are indicated: As replacement or supplemental therapy in patients with hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute thyroiditis This category includes cretinism, myxedema and ordinary hypothyroidism in patients of any age (pediatric patients, adults, the elderly), or state (including pregnancy); primary hypothyroidism resulting from functional deficiency, primary atrophy, partial or total absence of thyroid gland, or the effects of surgery, radiation, or drugs, with or without the presence of goiter; and secondary (pituitary) or tertiary (hypothalamic) hypothyroidism

The patient has a high TSH level (13,163 mUI/L), indicating hypothyroidism.

• The patient's condition falls under the category of ordinary hypothyroidism.
• Liothyronine (PO) can be used as replacement or supplemental therapy for this condition 2.
• The patient is an adult, which is included in the indicated age range for this treatment.

From the Research

Patient Profile

• Age: 36 years old
• TSH level: 13,163 mUI/L, indicating severe hypothyroidism

Treatment Considerations

• According to 3, newly diagnosed hypothyroid patients should be treated with levothyroxine (LT4)
• For patients who remain symptomatic on LT4 therapy, clinical guidelines recommend a trial of combination therapy with LT4 and liothyronine (LT3) 3
• The LT4/LT3 ratio should be considered, with a recommended ratio of 13:1-20:1 4
• Desiccated thyroid extract (DTE) is another form of combination therapy, but its use is not formally regulated by the FDA 3

Dose Titration

• Many LT4 preparations have limited tablet strengths, which can make it difficult to achieve the optimal dose 5
• The availability of intermediate tablet strengths of LT4 may facilitate more precise dose titration 5
• LT4 doses should be adjusted based on TSH levels, with the goal of achieving a normal TSH level 6, 7

Combination Therapy

• Combination therapy with LT4 and LT3 may be beneficial for patients who remain symptomatic on LT4 alone 3, 4, 7
• The use of LT3 in primary hypothyroidism is still being studied, and more clinical trials are needed to determine its effectiveness 4
• A recent feasibility trial found that LT4/LT3 combination therapy may prevent changes in weight and cholesterol associated with LT4 replacement alone 7

Monitoring and Adjustments

• Patients on LT4 therapy should be monitored regularly for TSH levels, free T4, and total T3 6, 7
• LT4 doses should be adjusted as needed to achieve a normal TSH level and prevent over- or under-treatment 6, 5