Assessment of a plasma ADH radioimmunoassay in experimental and physiologic or pathologic conditions

A radioimmunoassay of ADH has been applied to the study of plasma ADH levels in various conditions. The validity of the assay has been evaluated by the usual quality control parameters of RIA and by the measure of plasma levels in 12 upright water deprived normal volunteers (mean 9.5 pg/ml, SEM +/- 1.5) in 8 resting and hydrated normal volunteers (1.3 +/- 0.4 pg/ml), in a case of diabetes insipidus (1.6 pg/ml), in 8 cases of SIADH Syndrome (range 13-77 pg/ml) and in 4 anesthetized dogs before (33.7 +/- 9.2 pg/ml) and after acute haemorrhage (66 +/- 9.5 pg/ml, p less than 0.02). The osmotoic challenge to ADH secretion has been studied in 8 patients with no overt endocrine pathology by salt perfusion and showed a significant rise (p less than 0.05) of plasma ADH from 6.3 +/- 3.1 pg/ml before, to 20.6 +/- 7.9 pg/ml during salt infusion corresponding to the significant (p less than 0.0001) rise of plasma osmolality from 273 +/- 2.8 to 288.2 +/- 1.1 m Osm/kg.