Severity of hyperemesis gravidarum correlates with serum levels of reverseT-3

To investigate the possible physiological relevance of extra-thyroidal prod uction of reverse T-3 (rT(3)) in hyperemesis gravidarum, measurements of se rum rT(3), free T-3 (FT3), free T-4, (FT4), and nonesterified fatty acids ( NEFA) were correlated with weight loss of hyperemetic women. All the thyroi d hormones, NEFAs and weight loss were significantly higher in hyperemesis gravidarum than in control subjects, and also higher than in those with mil der symptoms of morning sickness (p < 0.05). Elevations of FT3, FT4 and NEF As correlated with the extent of weight loss, the latter taken as the index of the severity of hyperemesis gravidarum (p < 0.05). Only rT(3) correlate d with both weight loss and the rate of lipolysis, as reflected by elevatio ns of NEFAs (p < 0.05). The data are consistent with a shift from T-3 to rT (3) as products of 5'-monodeiodination of thyroxine in hyperemesis gravidar um. Because reverse T-3 is physiologically inactive a control mechanism may be postulated wherein T-3 production is minimized, thereby reducing weight loss and lipolysis in patients with hyperemesis gravidarum.