Posterior Pituitary Disorders: Anatomy and Physiology, Central Diabetes Insipidus (CDI), and Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

Arginine vasopressin (AVP) is vital in the maintenance of the body’s osmolality and water balance. Deficiency and excess of this hormone result in diabetes insipidus and the syndrome of inappropriate antidiuretic hormone (SIADH), respectively. In this chapter, we describe the physiology of fluid balance abnormalities in these disorders and our approach to evaluating and treating children with these conditions. Oxytocin, another hormone secreted by the posterior pituitary gland, plays a role in energy balance, and the physiology and possible future clinical roles of this hormone are also reviewed.