Clinical analysis of 65 cases of hyperemesis gravidarum with gestational transient thyrotoxicosis.

Aim: We investigated thyroid function and the impact of gestational transient thyrotoxicosis (GTT) on pregnancy outcome in patients with hyperemesis gravidarum (HG; n = 143) who were hospitalized for rehydration.

Methods: Serum thyroid-stimulating hormone (TSH), free T3 (FT3), free T4 (FT4), thyroid globulin antibody (TgAb), thyroid peroxidase antibody (TPOAb) and hCG were measured after admission.

Results: The total prevalence of thyrotoxicosis in HG was 48.3%; GTT was the main form (45.5%). The total incidence of GTT increased significantly if serum hCG was more than 80,000 IU/L, subclinical GTT if serum hCG was 80,000-140,000 IU/L and clinical GTT if serum hCG was more than 180,000 IU/L. GTT did not require antithyroid therapy. The course of TSH, FT3 and FT4 were followed in 34 cases of GTT; thyroid function normalized by the second trimester. Of 65 patients with GTT, two underwent abortions due to unplanned pregnancies, two delivered prematurely and two infants had macrosomia. There were no other complications. All newborns (n = 63) of mothers with GTT had normal TSH levels.

Conclusion: GTT is common in HG. The severity of GTT is related to serum hCG levels. In patients with HG and GTT, thyroid function normalized by the second trimester without antithyroid treatment. GTT did not affect pregnancy outcomes.