ESTIMATION OF URINARY ALDOSTERONE USING THIN-LAYER CHROMATOGRAPHY ANDFLUOROMETRY

Aims-To develop a fluorimetric method for the estimation of urinary al dosterone; to establish a normal range in 24 hour and overnight urine samples; and to investigate the use of overnight urines for detecting hyperaldosteronism. Methods-Essential steps include hydrolysis of the 18 conjugate to release aldosterone and its oxidation with Benedict's solution, followed by thin-layer chromatography on silica gel and deve lopment of fluorescence on the plate with sulphuric acid. Results-Ther e was a linear correlation between the amount of aldosterone and the a rea under the peak on the chromatogram. The mean intra-assay and inter assay coefficients of variation were 4.4% and 6.8%, respectively. The mean aldosterone excretion in 67 adults was 15.7 (SD 8.1) nmol/24 hour s. The mean overnight excretion in 65 adults was 2.6 (1.4) nmol/8 hour s. The method detected raised concentrations in patients with primary and secondary aldosteronism. Conclusions-This technique provides an ac curate means of assaying urinary aldosterone. Overnight estimations se em to be as effective as 24 hour assays for identifying patients with hyperaldosteronism.