[Estimation of the urinary aldosterone (author's transl)]

Area of Science:

• Endocrinology
• Clinical Chemistry
• Assay Development

Background:

• Aldosterone (ALD) is a key hormone in regulating blood pressure and electrolyte balance.
• Accurate measurement of urinary ALD is crucial for diagnosing and managing various endocrine and renal conditions.
• Existing RIA kits for urinary ALD often use specific diluents, impacting assay performance.

Purpose of the Study:

• To evaluate the use of a 10% bovine serum albumin (BSA) solution as a diluent in urinary aldosterone radioimmunoassay (RIA).
• To compare the measurement of free, HCl-conjugated, and beta-glucuronidase-conjugated aldosterone in urine.
• To investigate potential differences in urinary ALD levels across different health statuses.

Main Methods:

• Urinary aldosterone levels were measured using a radioimmunoassay (RIA) kit.
• Urine samples were diluted with a 10% solution of bovine serum albumin (BSA).
• Measurements included free ALD, HCl-ALD, and beta-glucuronidase ALD, with analysis of their correlations.

Main Results:

• The upper limits for free, HCl-ALD, and beta-glucuronidase ALD in BSA-diluted urine were 1.6, 9.0, and 9.5 µg/dL, respectively.
• Urinary conjugated forms (HCl-ALD and beta-glucuronidase ALD) were significantly higher than free ALD, approximately 3.5 and 4 times, respectively.
• A good correlation was observed among the three measurement methods (free ALD, HCl-ALD, beta-glucuronidase ALD).

Conclusions:

• A 10% BSA solution is a suitable diluent for urinary aldosterone RIA, enabling accurate measurement of different ALD forms.
• Urinary ALD levels showed no significant differences between healthy subjects and patients with essential hypertension, kidney diseases, or acute liver diseases.
• The findings support the utility of BSA-diluted RIA for assessing urinary aldosterone and its conjugates in clinical settings.