How can subclinical hypothyroidism be managed to improve fertility?

From the Guidelines

Subclinical hypothyroidism should be managed with levothyroxine supplementation to improve fertility, particularly when TSH levels exceed 2.5 mIU/L in women attempting pregnancy. The goal of treatment is to normalize TSH levels, which can help regulate menstrual cycles, improve ovulation rates, and create a more favorable endometrial environment for implantation 1.

Key Considerations for Management

• The standard approach is to start with levothyroxine at 25-50 mcg daily, taken on an empty stomach 30-60 minutes before breakfast.
• Dosage adjustments are made based on TSH monitoring every 4-6 weeks until levels are maintained between 1-2.5 mIU/L, which is considered optimal for conception.
• Once pregnant, women should increase their levothyroxine dose by approximately 30% and have TSH levels checked each trimester, aiming to keep TSH below 2.5 mIU/L in the first trimester and below 3.0 mIU/L in later trimesters.

Additional Recommendations

• Lifestyle modifications including selenium supplementation (200 mcg daily) and vitamin D optimization may provide additional benefits alongside medication therapy.
• Reducing environmental goitrogens is also recommended to support thyroid health and fertility.
• It is essential to note that while the USPSTF did not identify any clinical trials that evaluated the causal relationship between treatment and subsequent cardiac events in persons with subclinical hypothyroidism, treatment is still recommended to improve fertility outcomes 1.

Monitoring and Adjustments

• Regular TSH monitoring is crucial to adjust levothyroxine doses and maintain optimal TSH levels for conception and pregnancy.
• Women with subclinical hypothyroidism should work closely with their healthcare provider to manage their condition and improve fertility outcomes.

From the Research

Subclinical Hypothyroidism and Fertility

• Subclinical hypothyroidism is defined as elevated thyroid-stimulating hormone (TSH) with normal levels of free triiodothyronine (FT3) and free thyroxine (FT4) 2.
• The condition is common in women and increases with age, with a prevalence of up to 10% in the adult population 3.
• Subclinical hypothyroidism has been associated with an increased risk of adverse pregnancy outcomes, and some studies suggest that levothyroxine treatment may be beneficial in reducing these risks 2, 4.

Management of Subclinical Hypothyroidism to Improve Fertility

• The decision to treat subclinical hypothyroidism should be individualized, taking into account the patient's age, symptoms, and cardiovascular disease risk 5, 6.
• Levothyroxine treatment may be considered for patients with subclinical hypothyroidism and serum TSH levels of 10 mU/L or higher, or for young and middle-aged individuals with symptoms consistent with mild hypothyroidism 3.
• Treatment goals should be tailored to the individual patient, with TSH goals dependent on age, ranging from 3.6 mIU/L for patients under 40 to 7.5 mIU/L for patients over 80 6.
• In some cases, combined treatment with levothyroxine and liothyronine may be preferred for patients who are dissatisfied with treatment 6.

Considerations for Treatment

• The potential benefits of levothyroxine treatment in reducing cardiovascular disease risk and adverse pregnancy outcomes should be weighed against the potential risks of iatrogenic thyrotoxicosis, particularly in elderly patients 5, 3.
• Treatment decisions should be made on a case-by-case basis, taking into account the patient's specific characteristics and risk factors 4, 6.