Potential pitfalls in the radioimmunoassay of physiological plasma levels of atrial natriuretic peptide.

Certain aspects of current radioimmunoassay methodology are presented which may restrict accurate measurement of physiological changes in circulating plasma levels of atrial natriuretic peptide. These include the method of sample collection and time of storage, sample extraction, concentration and reconstitution, the homogeneity of tracer and standards, separation of bound from free ligand and the assessment of blank values. If left unchecked, inaccuracies at each of these stages may cumulatively result in unreliable assessment of changes in circulating ANP levels and limit further understanding of its physiological role.