Aldosterone Test

Aldosterone is one of the hormones produced by the adrenal glands, the small glands that sit atop each kidney. It belongs to a signaling system that helps the body hold on to or release sodium and water while balancing potassium. Because that balance shapes the amount of fluid in the bloodstream, aldosterone is closely tied to how blood pressure is regulated over time.

Aldosterone rarely acts alone. It sits within a chain that begins with a kidney signal and works through several steps, so clinicians frequently look at aldosterone together with a partner marker that reflects that upstream signal. Reading the two side by side gives a fuller picture than either one on its own, which is why the pairing is common in this kind of evaluation.

The test is done with a simple blood draw at a patient service center. A phlebotomist collects a sample from a vein, usually in the arm, and sends it to the laboratory. Aldosterone can shift with body position and time of day, so the timing of the draw and whether a person has been sitting, standing, or lying down can matter. People follow whatever preparation instructions their ordering clinician provides, since certain foods and medicines can also influence the result.

People who look into an aldosterone test are often working with a clinician on questions about blood pressure that has been difficult to manage, or about shifts in potassium noticed on other lab work. Symptoms such as muscle weakness, unusual fatigue, or frequent thirst sometimes prompt the conversation as well. The marker is a specialized one, so it is usually ordered as part of a considered workup rather than as a routine screen.

Because posture and timing influence the reading, this is a test people generally arrange with clinician guidance rather than on impulse. That guidance helps make sure the sample is collected in a way that gives the most useful result.

The aldosterone test measures how much of this adrenal hormone is present in the blood at the moment the sample is drawn. Aldosterone's role is to fine-tune the balance of sodium and potassium and, through that, the amount of fluid the body retains. When clinicians want to understand that salt-and-fluid conversation, aldosterone is one of the readings they turn to.

On its own, a single aldosterone value describes only part of the story. It reflects the hormone's output but not the upstream signal driving it, which is why a clinician often reads it against a partner marker to see whether the two are moving together or pulling in the opposite direction.

Aldosterone naturally rises and falls across the day and responds to whether a person is upright or lying down. Because of this, labs and clinicians pay attention to when the sample is taken and what position the body was in beforehand. Following the preparation notes an ordering clinician gives — about timing, posture, diet, and any medicines — helps the sample reflect what the clinician intends to measure.

Results will be emailed securely to you as a PDF.