Plasma Corticosteroid and Growth Hormone Response to Lysine-Vasopressin in Man

Abstract

Plasma 11-hydroxycorticosteroid values have been determined during continuous intravenous infusions of synthetic lysine-8-vasopressin and after its administration as single intravenous, intramuscular or subcutaneous injections, in an attempt to define the best procedure for investigating pituitary-adrenal function. The intramuscular injection of 10 pressor units (PU) proved most suitable. An adrenocortical response was obtained in all subjects studied when samples were taken 30 and 60 min after injection. The 3 criteria established for a normal response are: i) that the basal level should exceed 5 μg/100 ml, ii) the 30 and/or 60 min value should reach at least 16 μg/100 ml, and iii) the plasma 11-hydroxycorticosteroid increment should exceed 5 μg/100 ml. There was no advantage in prolonging the test beyond 1 hr. Side-effects were minimal with this procedure and there has been no clinical, electroencephalographic or electrocardiographic evidence of cerebral or myocardial ischemia. The plasma growth hormone response to lysine-8-vasopressin administration was variable. The presence, or absence, of a rise appeared to be related to the severity of sideeffects experienced.