Abnormal stimulation of the thyrotrophin receptor during gestation.
Pregnancy induces physiological alterations in thyroid function which may make difficult the interpretation of results of thyroid hormone measurement. A state of hyperstimulation of the thyroid gland is common in early pregnancy. In a few cases, thyroid hormone values will deviate from the normal range, which corresponds to the gestational transient thyrotoxicosis. This syndrome is closely associated with hyperemesis gravidarum. The relationship between the two syndromes, demonstrated by epidemiological studies, has been illustrated by an exceptional case of familial recurrent gestational thyrotoxicosis presenting as hyperemesis gravidarum due to hypersensitivity of the thyrotrophin receptor to hCG. However, the exact mechanisms of hyperemesis gravidarum have not yet been identified. Gestational transient thyrotoxicosis has to be distinguished from Graves' disease, because the latter is associated with potential maternal and fetal complications when thyrotoxicosis is not controlled, whereas the former has usually a favourable outcome. The existence of other cases of thyroid hypersensitivity or hCG endowed with abnormal thyrotrophic activity is suspected. They may be identified only by assessment of the thyroid function in cases of hyperemesis gravidarum. The identification of these cases would be helpful to understand the mechanisms of specificity of glycoprotein hormone receptors.
Rodien
Patrice
P
Service d'Endocrinologie, INSERM EMI U0018, Centre Hospitalier Universitaire d'Angers, Angers, France. PaRodien@chu-angers.fr
Jordan
Nicola
N
Lefèvre
Anne
A
Royer
Julien
J
Vasseur
Claudine
C
Savagner
Frédérique
F
Bourdelot
Aline
A
Rohmer
Vincent
V
D000595:Amino Acid Sequence; D006063:Chorionic Gonadotropin / Q000502:physiology; D005260:Female; D005865:Gestational Age; D006111:Graves Disease / Q000628:therapy; D006801:Humans; D006939:Hyperemesis Gravidarum / Q000209:etiology / Q000235:genetics; D006980:Hyperthyroidism / Q000209:etiology / Q000628:therapy; D008969:Molecular Sequence Data; D009154:Mutation; D011247:Pregnancy / Q000378:metabolism*; D011248:Pregnancy Complications / Q000209:etiology* / Q000628:therapy; D011989:Receptors, Thyrotropin / Q000502:physiology*; D012016:Reference Values; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000502:physiology; D013971:Thyrotoxicosis / Q000378:metabolism
D006063:Chorionic Gonadotropin; D011989:Receptors, Thyrotropin