From the Guidelines
Watchful waiting is not recommended for a TSH level of 2.78 when trying to conceive, as treatment with levothyroxine is advised to restore the serum TSH concentration to the reference range, even in the absence of overt hypothyroidism, due to the potential association between high TSH and increased fetal wastage or subsequent neuropsychological complications in the offspring 1.
Key Considerations
- The normal reference range for TSH is typically considered to be between 0.4-4.0 mIU/L, but some guidelines suggest that TSH levels should be below 2.5 mIU/L for women trying to conceive or undergoing fertility treatments.
- A TSH level of 2.78, although within the normal range, may still pose risks to fertility and pregnancy outcomes, particularly if it indicates subclinical hypothyroidism.
- Treatment with levothyroxine is generally recommended for women with elevated TSH levels, even if they are not overtly hypothyroid, to minimize potential risks to the fetus and support optimal fertility outcomes.
Monitoring and Treatment
- Regular monitoring of thyroid function every 6-12 months is reasonable while trying to conceive, but more frequent monitoring may be necessary for women with a history of thyroid disease or those undergoing fertility treatments.
- The requirement for levothyroxine in treated hypothyroid women frequently increases during pregnancy, so serum TSH concentration should be monitored every 6 to 8 weeks during pregnancy and the levothyroxine dose modified as needed 1.
- The risks of appropriately managed levothyroxine therapy in pregnancy are minimal, and the potential benefits of treatment outweigh the risks, particularly in terms of reducing the risk of fetal wastage and neuropsychological complications in the offspring.
From the Research
Thyroid-Stimulating Hormone (TSH) Levels and Conception
- A TSH level of 2.78 may not be considered optimal for conception, as guidelines recommend a preconception serum TSH level of <2.5 mU/l for hypothyroid infertile women 2.
- However, some studies suggest that variation in thyroid function within the normal range in women free of thyroid disease may not be associated with altered pregnancy outcomes 3.
- It is essential to note that the American Thyroid Association recommends an upper limit reference interval of TSH of 2.5 mIU/L in the first trimester of pregnancy and 3.0 mIU/L in subsequent trimesters 4.
Watchful Waiting Approach
- There is no clear evidence to support a watchful waiting approach for a TSH level of 2.78 when trying to conceive, as the optimal TSH range for conception is still debated.
- Some studies suggest that thyroxine therapy may enhance fertility in infertile women with clinical and subclinical hypothyroidism, but the evidence is not directly relevant to the watchful waiting approach 2, 5.
- In the absence of clear guidelines, it is crucial to consult with a healthcare provider to determine the best course of action for individual cases.
Considerations for Thyroid Function and Conception
- Thyroid function can impact fertility, and abnormal TSH levels may be associated with increased risk of infertility 2, 6.
- Women with hypothyroidism may require an increase in their levothyroxine dose during pregnancy to maintain optimal TSH levels 5.
- Trimester- and assay-specific thyroid reference intervals may vary, and it is essential to consider these factors when evaluating thyroid function during pregnancy 4.