From the Guidelines
For women with Hashimoto's thyroiditis attempting to conceive, optimal thyroid function is crucial, with target levels of TSH below 2.5 mIU/L, free T4 in the upper half of the normal range, and total T3 within normal limits, as evidenced by guidelines for diagnosis and management of subclinical thyroid disease 1. When attempting to conceive, it is essential to normalize not only thyroid function but also other critical labs, including:
- Vitamin D levels above 30 ng/mL
- Iron studies with ferritin above 50 ng/mL
- B12 levels above 400 pg/mL
- Folate levels within normal range Abnormal thyroid function during pregnancy can increase the risks of:
- Miscarriage
- Preterm birth
- Preeclampsia
- Gestational hypertension
- Placental abruption
- Neurodevelopmental issues in the baby While the patient prefers compounded thyroid medications, it is crucial to note that these lack the consistent potency, quality control, and evidence base of FDA-approved medications like levothyroxine, as highlighted in the guidelines for managing subclinical thyroid disease 1. If using compounded formulations, such as compounded T4/T3 combinations, more frequent monitoring is necessary to ensure stable thyroid levels. Regardless of medication choice, thyroid function should be checked:
- Before conception
- Immediately upon confirming pregnancy
- Every 4-6 weeks during the first trimester
- Less frequently thereafter The dose typically needs to be increased by 25-50% during pregnancy as requirements naturally increase, emphasizing the need for close monitoring and adjustment of thyroid medication during this critical period 1.
From the Research
Optimal Thyroid Hormone Levels for Conception
- The optimal TSH level for conception is not explicitly stated in the provided studies, but it is generally recommended to be within the normal range 2.
- Free T4 and total T3 levels should also be within normal ranges, but the exact optimal levels are not specified 2.
- It is essential to note that the presence of antithyroid antibodies (ATAs) alone, even with normal TSH levels, can have adverse effects on pregnancy 2.
Important Labs to be Normal Before Attempting Pregnancy
- TSH levels should be within the normal range 2.
- Free T4 and total T3 levels should be within normal ranges 2.
- Antithyroid antibody (ATA) levels, including thyroid peroxidase antibodies (TPOAbs), should be monitored as their presence is associated with an increased risk of recurrent miscarriages and preterm birth 3.
Risks to Pregnancy with Abnormal Thyroid Hormone Levels
- Abnormal TSH levels, even with normal free T4 and total T3 levels, can increase the risk of difficulty in conception, recurrent miscarriages, anemia, preeclampsia, and abruption 2.
- The presence of ATAs alone can also increase the risk of adverse pregnancy effects, including recurrent miscarriages and preterm birth 2.
- Hashimoto's disease can cause difficulty in conception, miscarriages, growth retardation, and preterm birth 2.
Alternative Treatment Options
- The use of IVIG (intravenous immunoglobulin) has been shown to be effective in improving obstetric outcomes in patients with Hashimoto's disease or the presence of ATAs alone 2.
- Compound medications may be considered as an alternative to traditional thyroid hormone replacement therapy, but their effectiveness and safety in pregnancy are not well established [no direct evidence provided].
- Levothyroxine (LT4) is the recommended treatment for hypothyroidism in pregnancy, and the dose should be based on the degree of preserved thyroid functionality and lean body mass 3.