24-Hour Urine Aldosterone Test

The aldosterone urine test is a quantitative measurement of the level of the hormone aldosterone or its primary metabolite (usually aldosterone-18-glucuronide) in a 24-hour urine sample. This measurement reflects the amount of aldosterone secreted by the adrenal cortex, metabolized, and then excreted by the kidneys over a 24-hour period. It provides a more stable and comprehensive estimate of the hormone's overall activity compared to individual blood measurements, which are highly sensitive to position, timing, and rapid fluctuations.