[Is there a relationship between hyperemesis gravidarum and hyperthyroidism?]

This retrospective study evaluates the incidence and degree of thyroidal stimulation in patients with hyperemesis, and the correlation between thyroid function, the hCG level and the severity of the hyperemesis gravidarum. The role of antithyroidea is discussed in patients with a gestational hyperthyroidism. The degree of thyroid stimulation on the outcome of the pregnancy was studied. At admission hCG, TSH, FT4, FT3, TSI, anti-TPO and anti-Tg were determined. The severity of the hyperemesis gravidarum was evaluated by the degree of ketonuria, % weight loss, and the electrolytes and the liver function disorders. An ultrasound to confirm the gestational age and to exclude a multiple pregnancy or a trophoblastic disease was carried out.

In a period of 1 January '91 to 31 January '94, 48 hyperemesis gravidarumpatients were admitted at the maternity. 22.9% of the hyperemesispatients had thyroid stimulation; 4 patients had a decreased TSH and an increased FT4 (group 2) and 7 patients had a decreased TSH, an increased FT4 and FT3 (group 3). The age of the mother, the parity and the gestational age at admission are comparable, and do not differ from the patients without thyroid disorders (group 1). Parameters, determining the severity of hyperemesis gravidarum, are not significantly different in the 3 groups. Treatment with antithyroidea in the group with proven hyperthyroidism (decreased TSH, increased FT4 and FT3) does not only lead to normalisation of the thyroid tests, but also to an improvement of the symptomatology. The gestational age at delivery and the birthweight of the babies are comparable in the 3 groups.

In patients admitted with hyperemesis gravidarum, we found 23% of the women to present a thyroid stimulation. This hyperthyroidism differs from the auto-immune hyperthyroidism, i.e. the patients have no thyroid antibodies, no classic clinical signs of thyrothoxicosis. Probably, the absolute hCG concentration and its biological activity plays a crucial role in the thyroid stimulation. This degree of thyroid stimulation has no influence on the severity of the hyperemesis gravidarum, neither on the outcome of the pregnancy.