Study of different factors affecting arginine-vasopressinradioimmunoassay

Since Robertson et al’s description of a radioimmunoassay (RIA) method [l] for the deter~nation of ar~nine-vasopressin (AVP) in human plasma, there have been several reports on the same subject. Some of the methods are not sensitive enough [2-81 for the detection of low levels of AVP in plasma, while others, although sensitive enough to detect these levels [9-161, use extraction methods which are too laborious. In addition, there is no general agreement on the stability of the samples ]7,9,10,13]. In this paper, we describe a sensitive method for plasma AVP measurement using a commercial antiserum and a simple method for extraction [7]. To obtain a labelled hormone with adequate specific activity and purity, most of the experimental work was dedicated to a detailed study of the purification procedure. The consequences of using metabisulphite in the iodination are discussed. We also report the results of a study on stability of AVP values in freeze-dried samples.