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August 20, 2019

Thyroid Function Test Abnormalities During Pregnancy

Author Affiliations
  • 1Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia
  • 2Associate Editor, JAMA
  • 3Division of Maternal and Fetal Medicine, Department of Obstetrics and Gynecology, University of Alabama at Birmingham
JAMA. 2019;322(7):617-619. doi:10.1001/jama.2019.10159

Thyroid hormones affect the growth, metabolism, and function of multiple organs in the body. If adaptive mechanisms were not in place during pregnancy, physiological increases in the quantity of circulating thyroid hormone–binding proteins would result in lower concentrations of unbound (free) thyroid hormones and subsequent adverse maternal and fetal consequences.1 Fortunately, the hypothalamic-pituitary-thyroid axis compensates, matching thyroidal output to maternal requirements, and, as long as the thyroid has adequate reserves, thyrotropin (often referred to as thyroid-stimulating hormone or TSH) and free thyroxine are maintained at normal concentrations.