[Kok! Health] "Preparing for Pregnancy... Should I Treat Subclinical Hypothyroidism?"

The prevalence of subclinical hypothyroidism in adult women is known to be around 3-8%. In this condition, blood thyroid hormone levels are normal, but thyroid-stimulating hormone (TSH) is elevated above the normal range. It is often asymptomatic and therefore referred to as asymptomatic hypothyroidism.

Thyroid reference photo.

This condition is common in women and its prevalence increases with age, with reports indicating it is found in 15-20% of women over 60 years old. Because there are no symptoms, it is often discovered incidentally during comprehensive health check-ups or diagnosed at obstetrics and gynecology clinics when preparing for pregnancy, leading patients to visit hospitals.

For those not considering pregnancy, treatment of subclinical hypothyroidism depends on the degree of TSH elevation and the presence of thyroid autoantibodies (anti-TPO antibodies, anti-Tg antibodies).

Dr. Oh Eun-sook, Head of Endocrinology at Mizmedi, explained, "Thyroid hormone (Synthroid or Euthyrox) supplementation is started when TSH levels are above 10 mIU/L. Even if TSH is in the range of 4.5-10 mIU/L, treatment is given if the patient is preparing for pregnancy, or if symptoms such as fatigue, constipation, or goiter are present, or if thyroid autoantibodies are positive. If treatment is not started, hormone levels are rechecked after 2-3 months."

Eun-sook Oh, Head of Endocrinology Department at Mizmedi Hospital.
[Photo by Mizmedi Hospital]

If pregnancy is being considered, thyroid function must be regulated more delicately and strictly because thyroid hormones are important for fetal brain neurodevelopment. The fetal thyroid function matures around 18-20 weeks of gestation, and before that, the fetus depends on thyroid hormones supplied by the mother.

Especially during pregnancy, the demand for thyroid hormones increases, and the presence of autoantibodies is associated with miscarriage, preterm birth, and postpartum thyroid dysfunction, so regular monitoring of TSH levels during pregnancy is necessary.

Dr. Oh stated, "Subclinical hypothyroidism during pregnancy is associated with an increased risk of pregnancy complications such as miscarriage and preterm birth, and studies also show a higher frequency of neurocognitive developmental disorders in the fetus. We recommend measuring TSH concentration and maintaining it within the normal range."

This content was produced with the assistance of AI translation services.