Some degree of stimulation of the thyroid gland by chorionic gonadotropin (see 118860) is common during early pregnancy. When serum chorionic gonadotropin concentrations are abnormally high, e.g., in women with molar pregnancies (231090), overt hyperthyroidism may ensue. The ... Some degree of stimulation of the thyroid gland by chorionic gonadotropin (see 118860) is common during early pregnancy. When serum chorionic gonadotropin concentrations are abnormally high, e.g., in women with molar pregnancies (231090), overt hyperthyroidism may ensue. The pathophysiologic mechanism appears to be promiscuous stimulation of the thyrotropin receptor by the excess chorionic gonadotropin. The explanation for this stimulation is the close structural relations between chorionic gonadotropin and thyrotropin and between their receptors (Grossmann et al., 1997).
Hyperemesis gravidarum is characterized by excessive vomiting in early pregnancy, leading to the loss of 5% or more of body weight. It is usually self-limited and therefore of little clinical consequence. Some women with the disorder have high ... Hyperemesis gravidarum is characterized by excessive vomiting in early pregnancy, leading to the loss of 5% or more of body weight. It is usually self-limited and therefore of little clinical consequence. Some women with the disorder have high serum thyroid hormone concentrations, and a few have sufficient clinical manifestations of hyperthyroidism to warrant short-term treatment with antithyroid drugs. Many, but not all, women with hyperemesis gravidarum and hyperthyroidism have high serum chorionic gonadotropin concentrations. Rodien et al. (1998) described mother and daughter with hyperemesis gravidarum associated with hyperthyroidism and normal serum concentrations of chorionic gonadotropin. They demonstrated that the thyrotropin receptor gene in the 2 women carried a heterozygous mutation, K183R (603372.0024), which rendered the thyrotropin receptor hypersensitive to chorionic gonadotropin. The daughter was a 27-year-old woman who was 10 weeks' pregnant when referred for the evaluation and treatment of hyperthyroidism. This was her third pregnancy, the first and second having resulted in early miscarriage accompanied by severe nausea and vomiting. In the third pregnancy, she again suffered severe nausea and vomiting and had a weight loss of 5 kg. She had tachycardia, excessive sweating, and tremor of the hands with a small, diffuse goiter and no ophthalmopathy. She was treated with propylthiouracil for 8 weeks with good results. After delivery of a normal girl at 38 weeks' gestation, propylthiouracil was discontinued. After an asymptomatic period, she returned 18 months later with recurrence of hyperthyroidism associated with hyperemesis gravidarum and was found to be pregnant again. Treatment with propylthiouracil was accompanied by a good response and delivery of a normal boy at 38 weeks' gestation. The mother was 27 years old when she gave birth to her daughter, 2 years after having a miscarriage. Both pregnancies were complicated by nausea, vomiting, and weight loss. The same symptoms recurred during a subsequent pregnancy, and the woman was treated with carbimazole for what was believed to be hyperthyroidism due to Graves disease, despite the absence of goiter and ophthalmopathy. After a normal delivery, the medication was discontinued and the patient remained euthyroid and had no further pregnancies.