Hyperthyroidism during pregnancy: Clinical manifestations, diagnosis, and causes
- Douglas S Ross, MD
Douglas S Ross, MD
- Section Editor — Thyroid Disease
- Professor of Medicine
- Harvard Medical School
- Section Editors
- David S Cooper, MD
David S Cooper, MD
- Editor-in-Chief — Endocrinology
- Section Editor — Pituitary Disease; Thyroid Disease
- Professor of Medicine and International Health
- Johns Hopkins University School of Medicine
- Charles J Lockwood, MD, MHCM
Charles J Lockwood, MD, MHCM
- Section Editor — Obstetrics
- Senior Vice President, USF Health
- Dean, Morsani College of Medicine
- Professor, Obstetrics and Gynecology
- University of South Florida
Overt hyperthyroidism (low thyroid-stimulating hormone [TSH], elevated free thyroxine [T4] and/or triiodothyronine [T3]) is relatively uncommon during pregnancy, occurring in 0.1 to 0.4 percent of all pregnancies [1,2]. The diagnosis of pregnant women with hyperthyroidism parallels that of nonpregnant women and men but presents some unique problems. The clinical manifestations, diagnosis, and causes of hyperthyroidism during pregnancy are presented here. The treatment of hyperthyroidism during pregnancy and other aspects of thyroid disease during pregnancy are discussed separately. (See "Hyperthyroidism during pregnancy: Treatment" and "Overview of thyroid disease in pregnancy".)
THYROID PHYSIOLOGY DURING NORMAL PREGNANCY
The diagnosis of thyroid disease during pregnancy requires an understanding of the changes in thyroid physiology and thyroid function tests that accompany normal pregnancy. These changes are reviewed briefly below and in more detail separately. (See "Overview of thyroid disease in pregnancy", section on 'Thyroid adaptation during normal pregnancy'.)
To meet the increased metabolic needs during a normal pregnancy, there are changes in thyroid physiology that are reflected in altered thyroid function tests. These changes include the following:
●Thyroid hormone-binding globulin (TBG) excess results in high serum total T4 and total T3 concentrations but not high serum free T4 or free T3 concentrations.
●High serum human chorionic gonadotropin (hCG) concentrations during early pregnancy and even higher concentrations in women with hyperemesis gravidarum or multiple pregnancies may result in transient subclinical or rarely overt hyperthyroidism.
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- THYROID PHYSIOLOGY DURING NORMAL PREGNANCY
- CLINICAL FEATURES
- Clinical manifestations
- Pregnancy complications
- Laboratory findings
- ESTABLISHING THE CAUSE
- Our approach
- Graves' disease
- hCG-mediated hyperthyroidism
- - Gestational transient thyrotoxicosis
- - Hyperemesis gravidarum
- - Trophoblastic hyperthyroidism
- - Familial gestational hyperthyroidism
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