Case report: Transient diabetes insipidus in pregnancy – a consequence of enhanced placental clearance of arginine vasopressin

We report a patient who presented with transient diabetes insipidus in pregnancy on a background of previous postoperative diabetes insipidus following surgical excision of a prolactinoma. The patient illustrates how the complex changes in water homeostasis occurring during normal pregnancy may unmask latent diabetes insipidus. The major factors operating appear to be a physiological reduction in the thresholds for thirst and arginine vasopressin secretion coupled with a substantial increase in placental clearance of arginine vasopressin. Reversal of these changes after delivery results in normalization of the disordered water homeostasis, with consequent resolution of the diabetes insipidus.