Thyroid hormone in hyperemesis gravidarum

Several studies have suggested that nausea and vomiting in early pregnancy are related to the levels of thyroid hormones and human chorionic gonadotropin (hCG). To ascertain this relationship, we investigated 60 pregnant women (30 subjects each with morning sickness and hyperemesis gravidarum) and compared them with 30 control subjects (by enzyme immunoassay method).

Serum T3, T4 and TSH were determined in all the subjects while serum hCG was assayed in pregnant women only. Group comparison was done by applying Student's t-test and the relationship between various parameters was evaluated by calculating coefficient of correlation, "r".

Serum T4 and hCG levels were significantly increased in hyperemesis gravidarum while TSH demonstrated a significant decline in the same group. Correlation analysis showed a direct relationship between serum T4 and hCG and an inverse relationship between serum TSH and hCG in pregnancy with morning sickness.

Our results are suggestive of the involvement of these variables in the pathogenesis of morning sickness and hyperemesis gravidarum not only because their levels were significantly altered but the extent of increase or decrease in their level correlated well with the severity of symptoms in the study subjects.