How are elevated Thyroid-Stimulating Hormone (TSH) levels treated?

From the Guidelines

Elevated TSH levels are primarily treated with synthetic thyroid hormone replacement therapy, most commonly levothyroxine (T4), with a treatment threshold of a TSH level greater than 10.0 mIU/L, as recommended by expert opinion 1.

Treatment Overview

The treatment approach for elevated TSH levels involves providing the synthetic version of the thyroid hormone that the body is not producing in sufficient quantities, which helps normalize metabolism and reverse symptoms of hypothyroidism.

• The typical starting dose for adults is 1.6 mcg/kg body weight daily, taken on an empty stomach 30-60 minutes before breakfast or 3-4 hours after dinner.
• Treatment is lifelong for most patients with hypothyroidism.
• Dosage adjustments are made based on follow-up TSH tests, usually checked 6-8 weeks after starting therapy or changing doses, with the goal of bringing TSH into the normal range (typically 0.4-4.0 mIU/L) 1.

Special Considerations

• Elderly patients or those with heart disease usually start at lower doses (25-50 mcg daily) with gradual increases.
• Patients should take the medication consistently at the same time each day and avoid taking it with calcium supplements, iron, antacids, or certain foods that can interfere with absorption.
• Regular monitoring is essential as both under-replacement and over-replacement can cause health problems.

Decision to Initiate Therapy

The decision of whether and when to begin therapy in patients with TSH levels between 4.5 and 10.0 mIU/L is more controversial, and it is not possible to differentiate persons who will have advancing thyroid dysfunction of clinical importance from those whose TSH levels will remain biochemically stable or even normalize 1.

• A large magnitude of overdiagnosis and overtreatment is a likely consequence of screening for thyroid dysfunction, particularly because the disorder is defined by silent biochemical parameters rather than a set of reliable and consistent clinical symptoms.
• The high variability of TSH secretion levels and the frequency of reversion to normal thyroid function without treatment underscore the importance of not relying on a single abnormal laboratory value as a basis for diagnosis or the decision to start therapy 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

The causes of high TSH levels are not directly stated in the provided drug label. However, the label does provide information on the treatment of elevated TSH levels.

• The treatment goal is to normalize the serum TSH level.
• Hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormones, leading to high TSH levels.
• In utero hypothyroidism can cause a resetting of pituitary-thyroid feedback, making it difficult to normalize TSH levels in some patients.
• Inadequate therapy can also lead to high TSH levels, which may be due to poor compliance, abnormal absorption, or drug interactions 2.

From the Research

Causes of High TSH

• High TSH levels can be caused by primary hypothyroidism, which is a common disorder due to inadequate thyroid hormone secretion 3
• TSH levels increase with age, and between 30% and 60% of high TSH levels are not confirmed on a second blood test 3
• Subclinical hypothyroidism, characterized by high blood TSH levels and normal free T4 levels, is usually asymptomatic but can progress to overt hypothyroidism at a rate of about 3% to 4% per year overall 3

Treatment of Elevated TSH Levels

• Levothyroxine therapy is the standard treatment for hypothyroidism, and the goal is to normalize serum TSH levels 3, 4
• The initial dose of levothyroxine is usually around 1.5 microg/kg per day, taken on an empty stomach, but may be lower for elderly patients or those with coronary artery disease 3
• Treatment monitoring is based mainly on blood TSH assay, and dose adjustment should only be considered after 6 to 12 weeks, given the long half-life of levothyroxine 3
• Some studies suggest that combination therapy with levothyroxine and liothyronine may be beneficial for some patients, particularly those with persistent symptoms or metabolic abnormalities despite normalization of serum TSH levels 5, 6, 7

Considerations for Treatment

• The risk of progression to overt hypothyroidism and the presence of symptoms should be taken into account when deciding on treatment 3
• Certain drugs, such as iron and calcium, can reduce the gastrointestinal absorption of levothyroxine, and enzyme inducers can reduce its efficacy 3
• Watchful waiting is an alternative to routine levothyroxine prescription in cases of TSH elevation, especially if the elevation is slight and the patient is asymptomatic 3