Radioimmunoassays of Tetrahydroaldosterone (Th-Aldo) in Human Urine

Abstract

Specific antisera against tetrahydroaldosterone (TH-Aldo) were raised in two white New Zealand rabbits. 3\g=a\,5\g=b\-TH-aldo-20-oxime-bovine-serum albumin complex was used as antigen. The resulting titers were 1:18 000 and 1:16 000. Except tetrahydrocortisol (THF) (0.23%) and tetrahydro\x=req-\ 18-hydroxy-11-dehydrocorticosterone (18-OH-THA) (3.2 %), all steroids and steroid metabolites gave negligible cross-reactions. Immunograms of the paper chromatograms made from the n-butanol-extract of the urines, as well as after \g=b\-glucuronidase treatment and dichlormethane extraction, were studied to further define the specificity of the antiserum. Antibody H1 (used in this study) reacted with aldosterone-18-gluc., a TH-aldosterone-glucuronide (probably the 21-glucuronide) and an unidentified less polar material. Two methods were developed: a) TH-Aldo-glucuronidc(s) estimation after ethylacetate pre-extraction as a rapid screening test of endogenous aldosterone production.b) estimation of TH-aldosterone using one chromatographic system. The results of method a) showed a significant correlation with the values obtained by technique b). Normal values (method b) were 25.88 \m=+-\16.50 \g=m\g/24h(range 9.5\p=n-\64.8 \g=m\g/24h). A significant correlation was also shown between the TH-aldo (technique b) and 18-gluc. values.TH-Aldo is the major metabolite of aldosterone isolated from human urine (Ulick 8c Liebermann 1957; Ulick 8c Vetter 1962). It is formed in the liver and excreted as glucuronide. 15-40°/o of the secreted aldosterone is excreted in the Partly presented at the

The effect of chronic ACTH treatment on blood pressure and urinary excretion of steroids in the rat

“…From 5 untreated rats (body weight 322.7+ 12.9 g), urine was collected for 15 consecutive days. In the urine samples, radioimmunological determinations of the 24-h excretion of the following steroids was performed: corticosterone, 18-OH-corticosterone, aldosterone, TH-aldosterone, and 18-OH-DOC [3, 8,9]. Blood pressure was measured by tail plethysmography under light ether anesthesia.…”

Role of Intestinal Bacteria in the Metabolism of Aldosterone in Man

“…The measurement of urinary aldosterone metabolites has been postulated to be of diagnostic value [10]. How ever, it is important to avoid the administration of non absorbable antibiotics when measuring 2 1-deoxy metab olites in the urine.…”

“…Details of the assay procedures were as reported by Kohl et al [ 10] for THAldo, by Lewicka et al [ 11 ] for 2 1 -deoxy-THAldo and by Connolly et al [9] for free aldosterone. Urinary free aldosterone and unconjugated 21 -deoxy-Aldo were measured by RIA after extraction with dichloromethaldone and subsequent chromatography on silica gel-ethyl alcohol microcolumns for free aldosterone and paper chro matography using a solvent system of benzene:isooctane/methaldonol: water, 4:1/3:2 (v/v), for 2 1-deoxy-Aldo.…”

21-Deoxytetrahydroaldosterone Excretion in Primary Hyperaldosteronism

“…Interassay variation was ± 5.2%(n = 11), intraassay variation ± 4.7%(n = 18). The details of the determinations of tetrahydroal dosterone and aldosterone-18-glucuronide were pub lished previously [4,8].…”

“…However, this hy pothesis could not be proved because assays for 21-deoxytetrahydroaldosterone were not available. Using the antibody raised to tetrahydroaldosterone-20-oxime bovine serum albumin [4], which cross-reacts strongly with 21-deoxytetrahydroaldosterone, our group has developed a fairly sensitive and specific assay for the latter compound [5], The devel opment of a radioimmunoassay (RIA) was followed by an attempt to evaluate the diag nostic value of the measurement of urinary 21-deoxytetrahydroaldosterone in primary aldosteronism.…”