Aldosterone-to-renin ratio (ARR) is the mass concentration of

aldosterone Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays a c ...

divided by the

plasma renin activity Plasma renin activity (PRA), also known as the renin (active) assay or random plasma renin, is a measure of the activity of the plasma enzyme renin, which plays a major role in the body's regulation of blood pressure, thirst, and urine output. Me ...

or by serum renin concentration in blood. The aldosterone/renin ratio is recommended as screening tool for

primary hyperaldosteronism Primary aldosteronism (PA)'','' also known as primary hyperaldosteronism or Conn's syndrome, refers to the excess production of the hormone aldosterone from the adrenal glands, resulting in low renin levels and high blood pressure. This abnormalit ...

.
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Tests

There is more than one way to measure the ratio. Before sampling, the patient must have a high level of blood sodium. * 24-hour urinary excretion of aldosterone test: the patient eats a high-salt diet for a few days followed by urine collections over a 24-hour period * sodium infusion test: the patient has a blood infusion of a salt (sodium chloride) solution a few hours before blood collection

Interpretation

Aldosterone-to-renin ratio can be given in ng/dL per ng/(mL·h), that is,

nanogram To help compare different orders of magnitude, the following lists describe various mass levels between 10−59 kg and 1052 kg. The least massive thing listed here is a graviton, and the most massive thing is the observable universe. ...

per

deciliter The litre (international spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3). ...

of aldosterone per nanogram per (milliliter x hour) of renin. Also, it can be given in pmol/L per µg/(L·h), where aldosterone is given in

molar concentration Molar concentration (also called molarity, amount concentration or substance concentration) is a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solut ...

. The former can be converted to the latter by multiplying by 27.6. Also, the inverse value is occasionally given, that is, the ''renin-to-aldosterone ratio'', whose value is the

multiplicative inverse In mathematics, a multiplicative inverse or reciprocal for a number ''x'', denoted by 1/''x'' or ''x''−1, is a number which when Multiplication, multiplied by ''x'' yields the multiplicative identity, 1. The multiplicative inverse of a rat ...

of the ''aldosterone-to-renin ratio''. The cutoff normal individuals from those with primary hyperaldosteronism is significantly affected by the conditions of testing, such as posture and time of day. On average, an ARR cutoff of 23.6 ng/dL per ng/(mL·h), expressed in alternative units as 651 pmol/L per µg/(L·h), has been estimated to have a sensitivity of 97% and specificity of 94%.
Aldosterone-Renin Ratio in Primary Hyperaldosteronism
' by Allan S. Brett. Posted: 03/15/2005; Journal Watch. 2005;4(2) An ARR value in an individual that is ''higher'' than the cutoff indicates primary hyperaldosteronism. If the inverse ratio (i.e. renin-to-aldosterone) ratio is used, a value ''lower'' than the cutoff indicates primary hyperaldosteronism.

References

{{reflist Endocrinology

Tests

Interpretation

See also

References