What is the treatment for hypothyroidism (underactive thyroid)?

From the Guidelines

Hypothyroid treatment primarily involves thyroid hormone replacement therapy with levothyroxine (T4), typically starting at 1.6 mcg/kg/day for most adults, as recommended by the USPSTF 1.

Key Considerations

• Elderly patients or those with heart disease should begin with lower doses (25-50 mcg/day) and gradually increase.
• The medication should be taken on an empty stomach, 30-60 minutes before breakfast or 3-4 hours after the last meal of the day, avoiding calcium, iron supplements, and certain foods that can interfere with absorption.
• TSH levels should be checked 6-8 weeks after starting treatment or changing doses, with a target TSH of 0.5-2.5 mIU/L for most adults.
• Once stabilized, annual TSH monitoring is recommended.
• Some patients may benefit from combination therapy with liothyronine (T3) if symptoms persist despite normal TSH levels.

Treatment Goals

• Treatment is typically lifelong for permanent hypothyroidism.
• Proper treatment restores normal metabolism by replacing the thyroid hormones that regulate numerous bodily functions, including heart rate, body temperature, and energy production.
• Untreated hypothyroidism can lead to fatigue, weight gain, cold intolerance, and more serious complications like heart problems and myxedema coma.

Important Notes

• The USPSTF found no direct evidence that treatment of thyroid dysfunction based on risk level alters final health outcomes 1.
• Overdiagnosis and overtreatment are concerns, as they can lead to unnecessary treatment and potential harms 1.

From the FDA Drug Label

The general aim of therapy is to normalize the serum TSH level TSH may not normalize in some patients due to in utero hypothyroidism causing a resetting of pituitary-thyroid feedback. Failure of the serum T4 to increase into the upper half of the normal range within 2 weeks of initiation of levothyroxine sodium therapy and/or of the serum TSH to decrease below 20 IU per litre within 4 weeks may indicate the patient is not receiving adequate therapy In adult patients with primary hypothyroidism, monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dosage. In patients on a stable and appropriate replacement dosage, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient’s clinical status Hypothyroidism treatment involves the use of levothyroxine sodium to normalize serum TSH levels.

• The goal of therapy is to normalize the serum TSH level.
• Monitoring of serum TSH levels is necessary to adjust the dosage of levothyroxine sodium.
• The dosage of levothyroxine sodium may need to be increased during pregnancy.
• Patients with hypothyroidism should be closely monitored for signs of overdosage, such as hyperthyroidism. 2

From the Research

Hypothyroidism Treatment Overview

• Hypothyroidism is a common condition that affects up to 5% of the global population, with incidence increasing with age and being more common in women 3.
• The treatment of hypothyroidism with levothyroxine is effective and simple, but recommendations for the starting dose vary considerably 4.

Levothyroxine Treatment

• A full starting dose of levothyroxine in cardiac asymptomatic patients with primary hypothyroidism is safe and may be more convenient and cost-effective than a low starting dose regimen 4.
• Many hypothyroid patients start levothyroxine treatment at a low dose, especially the elderly, those with residual thyroid function, those with low body weight, and those with significant comorbidities 5.
• The availability of intermediate tablet strengths of levothyroxine may facilitate precise and effective dose titration and enable convenient maintenance regimens based on a single tablet daily 5.

Diagnosis and Treatment Considerations

• Diagnosis of hypothyroidism relies on simple-to-obtain, fairly inexpensive testing of thyroid-stimulating hormone (TSH) levels and confirmation with levels of thyroxine 3.
• Management of hypothyroidism usually involves monotherapy with levothyroxine taken on an empty stomach, with follow-up involving regular assessment of TSH levels and symptom relief 3.
• Levothyroxine monotherapy is the standard treatment for hypothyroidism, but 10% of patients have persistent symptoms of ill health despite normalization of thyroid function tests biochemically 6.

Laboratory Testing and Pitfalls

• Laboratory tests are integral in the management of thyroid conditions, but there are possible pitfalls and caveats in the use of these tests that need to be considered 7.
• TSH and free thyroid hormone tests are frequently used to assess the functional status of the thyroid, while TPO-Ab and TRAb tests are used to diagnose Hashimoto's thyroiditis and Graves' disease, respectively 7.