Transient non-autoimmune hyperthyroidism of early pregnancy

Abstract

It is characterized by chemical and sometimes clinical hyperthyroidism, without evidence of thyroid autoimmunity that resolves spontaneously by 16 weeks gestation without significant obstetrical complications.

Figure 1

A representative example of transient hyperthyroidism of hyperemesis gravidarum. By week 6, vomiting begins and becomes severe by week 10. Serum-free thyroxine (T4) index is elevated and thyrotropin is suppressed. By weeks 16 to 18, vomiting subsides with marked improvement of the free T4 index value. During this period, the patient loses 3.6 kg. By week 18, the serum free T4 index returns to normal, but the serum thyrotropin remains suppressed until week 26. Patient regains and gains weight with a term delivery of a healthy infant. The gray band indicates reference range. LNMP: last normal menstrual period. Patil-Sisodia and Mestman [12].

Figure 2

Relation between peak nausea and vomiting symptoms and human chorionic gonadotropin (hCG) levels. Niebyl [10].

Figure 3

Serum hCG and TSH as a function of gestational age Glinoer et al. [1].

Figure 4

Relation between the severity of vomiting and serum concentrations of TSH, free T4, and hCG (mean + SE). Hormone concentrations differed significantly between each group of patients except as indicated by NS Goodwin et al. [13].

Figure 5

(a) Serum thyrotropic activity (measured as iodide uptake in cultured rat cells) in hyperemesis patients and pregnant controls, mean + SE, P < 0.001) (b) correlation of serum hCG versus serum thyrotropic activity in hyperemesis and pregnant controls, r = 0.50, P < 0.001 Goodwin et al. [13].