Human chorionic gonadotropin: a secretory hormone.

There are several physiological and pathophysiological situations where there is an apparent fluid flux across plasma membranes at the time when human chorionic gonadotropin (hCG) levels are high. These fluxes may take the form of a fluid loss from gastrointestinal tract (e.g. emesis/hyperemesis gravidarum) or accumulations in enclosures (e.g. amniotic fluid or hydatidiform mole). What is not obvious though is whether hCG is the cause of these fluid fluxes. Although glycoprotein hormones like hCG are mainly hormonogenic, their action in the latter process involves the efflux or conductance of halide ions. Since the basis of fluid secretion is an active efflux of ions such as chloride stimulated by a humoral agent, accompanied by a passive diffusion of water across a cell wall, I hypothesize that hCG is also a secretory hormone and responsible for fluid fluxes in the above and other clinical situations.