From the Guidelines
Subclinical hypothyroidism should be treated with levothyroxine in patients with TSH levels above 10 mIU/L, and may be considered in those with TSH levels between 4.5-10 mIU/L who have symptoms, positive thyroid antibodies, or cardiovascular risk factors. The decision to treat subclinical hypothyroidism depends on several factors, including TSH level, symptoms, and individual patient characteristics. For patients with TSH levels above 10 mIU/L, treatment with levothyroxine is generally recommended 1.
Key Considerations
- TSH levels: Patients with TSH levels above 10 mIU/L should be treated with levothyroxine.
- Symptoms: Patients with symptoms of hypothyroidism, such as fatigue, weight gain, or cold intolerance, may benefit from treatment.
- Thyroid antibodies: Patients with positive thyroid antibodies may be at increased risk of progressing to overt hypothyroidism and may benefit from treatment.
- Cardiovascular risk factors: Patients with cardiovascular risk factors, such as high blood pressure or high cholesterol, may benefit from treatment to reduce their risk of cardiovascular disease.
Treatment
- Levothyroxine: The typical starting dose of levothyroxine is 25-50 mcg daily, taken on an empty stomach 30-60 minutes before breakfast.
- Dose adjustments: Dose adjustments are made based on TSH levels checked every 6-8 weeks until stabilized, then annually.
- Pregnant women: Pregnant women or those planning pregnancy should be treated even with mild elevation to prevent complications.
- Elderly patients: Elderly patients without symptoms may be monitored without treatment.
Goals of Therapy
- Normalize TSH levels: The goal of therapy is to normalize TSH levels, typically between 0.5-4.5 mIU/L.
- Alleviate symptoms: Treatment is also aimed at alleviating symptoms of hypothyroidism, such as fatigue, weight gain, or cold intolerance.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Definition and Diagnosis of Subclinical Hypothyroidism
- Subclinical hypothyroidism is characterized by elevated thyroid-stimulating hormone (TSH) levels with normal serum free thyroxine (fT4) and triiodothyronine (fT3) levels 2.
- 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 3.
Treatment of Subclinical Hypothyroidism
- Treatment is not necessary unless the TSH exceeds 7.0-10 mIU/L 3.
- Levothyroxine (T4) therapy is the preferred therapy in patients with definite and persistent TSH elevation 4.
- The biochemical treatment goal for T4 replacement in primary hypothyroidism is a TSH level within the reference range (0.4-4.0 mU/l) 2.
- T4/liothyronine (T3) combination therapy may be considered in patients with persistence of symptoms, despite optimal T4 treatment, based on expert opinion 2, 5.
Cardiovascular Disease Risk and Subclinical Hypothyroidism
- Subclinical hypothyroidism has been associated with risk factors for cardiovascular disease, such as hypertension and dyslipidemia 6.
- The use of levothyroxine in subclinical hypothyroidism to reduce cardiovascular disease risk is not clearly beneficial, and treatment decisions should be individualized based on patient age, degree of serum TSH elevation, symptoms, cardiovascular disease risk, and other co-morbidities 6.
- While cardiovascular events may be reduced in patients under age 65 with subclinical hypothyroidism who are treated with levothyroxine, treatment may be harmful in elderly patients with subclinical hypothyroidism 3.