During normal pregnancy, thyroid function tests in a euthyroid woman typically show which pattern?

• A Decreased TBG, increased free T4, decreased TSH
• B Normal TBG, increased free T4, decreased TSH
• C Increased TBG, decreased free T4, increased TSH
• D Increased TBG, normal free T4, normal TSH ✓

Explanation

Estrogen increases thyroid-binding globulin (TBG) production, raising total T4 and T3. However, free T4 and TSH remain normal in euthyroid women because the hypothalamic-pituitary-thyroid axis compensates. hCG in early pregnancy can mildly suppress TSH due to structural similarity to TSH, but free T4 stays normal.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.