Gestational diabetes insipidus and intrauterine fetal death of monochorionic twins.

Gestational diabetes insipidus (GDI) is a rare disorder. The onset is usually in the third trimester of pregnancy. We present a 24-year-old primigravida in her 35th week of a monochorionic-diamniotic twin pregnancy. The patient presented with intrauterine death of both twins accompanied by HELLP syndrome, hypernatremia and hemoconcentration. Urine osmolality below that of the plasma suggested GDI. 1-deamino-8D-arginine vasopressin (dDAVP) treatment was started with a quick response. GDI is probably the result of excessive activity of placental vasopressinase. In cases of liver dysfunction, the clearance rate of vasopressinase decreases, explaining the association of GDI with acute fatty liver and HELLP syndrome. Alert to this diagnosis, its evaluation and treatment is important.