Pitfalls in the assessment of gestational transient thyrotoxicosis

Abstract

Gestational transient thyrotoxicosis (GTT) is associated with direct stimulation of the maternal thyroid gland by human chorionic gonadotropin (hCG). It is characterized by slightly higher thyroid hormone and lower thyroid-stimulating hormone (TSH) levels in early pregnancy and mild or no symptoms. While GTT must be distinguished from Graves’ disease (GD), which is associated with maternal and fetal complications, treated GD and new-onset GD in pregnancy are occasionally challenging to distinguish. Evaluating serum hCG levels and TSH receptor antibody (TRAb) titers can help, but the results are not irrefutable due to pregnancy-related immunosuppression. Moreover, GTT can follow unusual clinical courses in relation to some pregnancy complications. Excessive hCG production can cause severe GTT symptoms in patients with hyperemesis gravidarum, trophoblastic disease, or multiple pregnancies. Thyrotoxicosis can emerge beyond the second trimester in patients with gestational diabetes mellitus and mirror syndrome, because of delayed elevations in the hCG levels. Detailed knowledge about GTT is necessary for correct diagnoses and its appropriate management. This review focuses on the diagnosis of GTT, and, particularly, its differentiation from GD, and unusual clinical conditions associated with GTT that require comprehensive management.

摘要

妊娠期一过性甲状腺毒症(GTT)与人绒毛膜促性腺激素(HCG)直接刺激母体甲状腺有关。它的特点是怀孕早期甲状腺激素略高, 促甲状腺激素(TSH)水平较低, 轻微症状或没有症状。然而, GTT必须与Graves病(GD)相区别, Graves病与母婴并发症有关, 但妊娠期已经经过治疗的GD和新发的GD有时很难区分。评估血清hCG水平和TSH受体抗体(TRAb)效价可能会有所帮助, 但由于与妊娠有关的免疫抑制, 结果并不是完全准确的。此外, 可以由于妊娠相关的并发症而对GTT施行一些非常规的临床措施。有妊娠剧吐、滋养细胞疾病或多胎妊娠的患者由于hCG的产生过多会导致出现严重的GTT症状。由于妊娠期糖尿病和镜像综合征患者的hCG水平升高延迟, 甲状腺功能亢进症可能会出现在妊娠中期以后。对GTT的正确诊断和处理必须具备GTT的相关知识。这篇综述主要针对于GTT的诊断, 特别是它与GD的鉴别, 以及与GTT相关的需要综合治疗的非常规临床情况。

The Chinese abstracts are translated by Prof. Dr. Xiangyan Ruan and her team: Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China.

Keywords:

• Gestational transient thyrotoxicosis
• Graves’ disease
• human chorionic gonadotropin
• pregnancy
• thyroid-stimulating hormone receptor antibody

Acknowledgement

The author received no specific funding.

Disclosure statement

No potential conflict of interest was reported by the author(s).