Transient postpartum diabetes insipidus in twin pregnancy associated with HELLP syndrome.

Diabetes insipidus during pregnancy is an uncommon medical problem, and its cause is not entirely clear. We present a woman with twin pregnancy associated with HELLP syndrome, who developed diabetes insipidus during postpartum period. A hypertonic saline infusion study with measurement of plasma arginine vasopressin concentrations confirmed the diagnosis. She had mild response to 1-desamino-8-d-arginine-vasopressin (dDAVP) during the immediate postpartum period. On the 3rd postpartum day two doses of 100 microliters of dDAVP were administered, and her urinary volume gradually decreased. We could stop dDAVP on the 30th postpartum day. This exacerbation may result from increased vasopressinase activity caused by the excessive production in the placenta due to twin pregnancy, together with the insufficient degradation in the liver due to HELLP syndrome.