Aldosterone

Ranges depend on whether the person was lying down or upright, on salt intake, the time of day and the assay (for example 100 to 450 pmol/L lying and 100 to 800 upright on older assays, lower on newer mass spectrometry methods), so the printed range and posture matter.

Aldosterone is a hormone from the outer layer of the adrenal glands that tells the kidneys to hold on to salt and water and to let go of potassium. It is one of the main controls on blood pressure and blood volume. It rises when the body is short of salt or fluid and falls when there is plenty.

It is requested, nearly always with renin, when high blood pressure is difficult to control, starts at a young age or comes with low potassium, to look for the adrenal condition called primary aldosteronism. It is also used when adrenal failure or unusual salt and potassium results are being looked into.

• Standing up, being short of fluid or eating little salt, which are normal responses
• Diuretic (water) tablets and some blood pressure tablets
• Primary aldosteronism, where an adrenal nodule or both glands make too much
• Heart failure, liver cirrhosis and kidney artery narrowing, through high renin
• Pregnancy and the second half of the menstrual cycle
• Morning sampling

• A high-salt diet and lying flat
• Adrenal gland failure (Addison's disease)
• Some blood pressure tablets, particularly beta-blockers
• Liquorice and some steroid medicines
• Older age, slightly, in the general population
• Rare inherited conditions

• Posture, salt intake and the time of day change it two- or three-fold
• Most blood pressure tablets and water tablets move it, so doctors often change medicines for a few weeks before the test
• The second half of the cycle and pregnancy raise it
• Different assays give quite different numbers

Usually a morning sample after being up and about for two hours, on a normal-salt diet, with potassium in range, and often after certain blood pressure tablets have been paused under medical supervision. Renin is taken at the same time. The posture and the medicines being taken should be recorded.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.