Treatment of TSH 2.78 When Trying to Conceive
Women who are trying to conceive with a TSH level of 2.78 mIU/L should be treated with levothyroxine to lower TSH into the optimal range for pregnancy.
Rationale for Treatment
A TSH level of 2.78 mIU/L falls within the general population reference range (0.45-4.5 mIU/L) 1, but requires special consideration in women attempting to conceive due to:
Pregnancy-specific thyroid requirements: The thyroid has increased demands during pregnancy, and untreated subclinical hypothyroidism is associated with adverse pregnancy outcomes.
Evidence-based recommendations: The ACOG practice bulletin specifically recommends treating elevated TSH in women planning pregnancy 1.
Potential benefits: Treatment may reduce the risk of pregnancy loss, which has been shown to be significantly lower in women whose levothyroxine dose was adjusted early in pregnancy (2.4% vs 36.4%) 2.
Treatment Algorithm
Step 1: Confirm the diagnosis
- Repeat TSH measurement along with Free T4 to confirm results
- Check for anti-TPO antibodies (optional but helpful for prognosis) 1
Step 2: Initiate treatment
- Start levothyroxine at appropriate dosage (typically 50-75 mcg daily)
- Target TSH level should be within the reference range, ideally in the lower half for women trying to conceive 1
Step 3: Monitoring
- Recheck TSH every 4-6 weeks until stable
- Once pregnant, check TSH every trimester 1
- Adjust dosage as needed to maintain optimal levels
Clinical Considerations
Why treat a "normal" TSH?
While 2.78 mIU/L is within the general population reference range, some experts suggest that the upper limit of normal for TSH should be 2.5 mIU/L in a rigorously screened population 1. More importantly, women planning pregnancy represent a special population where treatment is justified based on:
- Higher risk of progression to overt hypothyroidism during pregnancy
- Potential adverse pregnancy outcomes including increased fetal wastage
- Possible neuropsychological complications in offspring 1
Potential benefits of treatment
- Reduced risk of pregnancy loss 2
- Prevention of progression to overt hypothyroidism during pregnancy
- Optimization of maternal thyroid function during critical periods of fetal development
Important Caveats
Monitoring is essential: Once pregnant, thyroid requirements typically increase, necessitating dose adjustments every 4-8 weeks during pregnancy 1.
Avoid overtreatment: Excessive levothyroxine can lead to subclinical hyperthyroidism, which occurs in 14-21% of treated individuals 1.
Post-conception care: If conception occurs, continue treatment and inform the obstetrician about thyroid status to ensure proper monitoring throughout pregnancy.
Long-term considerations: After pregnancy, reassess the need for continued therapy based on postpartum thyroid function tests.
By treating a TSH of 2.78 mIU/L in women trying to conceive, you're taking a proactive approach to optimize thyroid function before and during pregnancy, potentially improving both fertility and pregnancy outcomes.