Determinants of plasma arginine-vasopressin in children.

Plasma concentration of arginine-vasopressin (AVP) was measured in 145 healthy subjects aged one day to 18 years of age. AVP decreased with age immediately after birth. Above one year of age values of children did not significantly differ from those in adults. AVP significantly correlated with plasma and urine osmolality after water deprivation during 16 h. Plasma AVP rose during exercise and fell after volume expansion. Nausea and vomiting are potent nonosmotic determinants of AVP release in children. Nonosmotic factors of AVP release should be controlled when sampling blood for measuring AVP in children for diagnostic and investigational purposes.