Is Subclinical Hypothyroidism in Pregnancy Diagnosed Too Often?

Variations inherent in the secretion and measurement of TSH will always make diagnosis uncertain.

Despite disagreement about the threshold for identifying first-trimester subclinical hypothyroidism, most organizations view a thyroid stimulating hormone (TSH) value >2.5 mIU/L in the presence of normal thyroxine (T4) levels as diagnostic. But how often is this diagnosis erroneous, resulting in prescription of supplemental thyroxine for the rest of the pregnancy? Investigators in Poland assessed baseline serum concentrations of free T4, free triiodothyronine (T3), and TSH at 30-min intervals for a 2-hour morning period in 110 pregnant women (mean gestation, 9.9 weeks) and 19 nonpregnant women of similar mean age (range, 29–30) and body-mass index (range, 25–28 kg/m²).

TSH levels in pregnant women averaged 1.6 ± 1.2 mIU/L but varied by almos…

Reviewing Author

Robert W. Rebar, MD

Disclosures

Consultant/Advisory BoardMyovant Sciences, Inc.

Editorial BoardsEndoText; Clinical OB/GYN Alert

Leadership Positions in Professional SocietiesAmerican Society for Reproductive Medicine (Member, Ethics Committee)

Robert W. Rebar, MD

Disclosures

Consultant/Advisory BoardMyovant Sciences, Inc.

Editorial BoardsEndoText; Clinical OB/GYN Alert

Leadership Positions in Professional SocietiesAmerican Society for Reproductive Medicine (Member, Ethics Committee)

Is Subclinical Hypothyroidism in Pregnancy Diagnosed Too Often?

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Reviewing Author