Methodological simplifications in radioimmunoassay of urinary aldosterone

• Published in: Clinica chimica acta Vol. 66; no. 3; pp. 331 - 343
• Main Authors: Malvano, R., Orlandini, S., Cozzani, P., Duranti, P., Simonini, N., Salvetti, A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 02.02.1976
• Subjects: Aldosterone - urine; Animals; Cross Reactions; Glucuronates - urine; Humans; Hydrogen-Ion Concentration; Hydrolysis; Rabbits - immunology; Radioimmunoassay - methods; Sodium - urine
• ISSN: 0009-8981; 1873-3492
• DOI: 10.1016/0009-8981(76)90232-1

Simplification of radioimmunoassay procedures of urinary aldosterone-18-glucuronide was attempted, taking into consideration the aspects implied by the hydrolysis of urine and the assay itself. The procedure standardized for the hydrolysis step (samples diluted with a two-fold volume of 0.2 N HC1 and incubated at 30°C for 16–24 h) proved suitable in terms of practicability and accuracy. Aldosterone antisera, raised m the rabbit against an aldosterone-3-bovine albumin conjugate, were selected according to their specificity towards competing steroids. Depending on the characteristics of the antisera used, an assay of extracts, or even direct measurements of hydrolyzed urines excluding any extraction, were found to yield reliable results. In the case of a high-quality antiserum, evidence for the adequacy of assay of non-hydrolyzed urine extracts for the measurement of the excretion of unconjugated aldosterone was provided by some preliminary data. The results of the experiments, directed at the methodological and clinical validation of the simplified procedures, are reported and discussed in this paper.