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Renin Activity and Aldosterone:Renin ratio (ARR)

Chemical Pathology

Notes

Aldosterone:Renin Ratio (ARR)

  • ARR is useful in the investigation of hypertension, especially in resistant hypertension, persistent hypokalaemia (but note that 50% patients with aldosterone producing adenomas are reportedly normokalaemic), or if no obvious cause is found for hypertension in a younger patient.
  • The renin-aldosterone axis is primarily regulated by renal blood flow. Patients under investigation should therefore not be taking any drugs that interfere with fluid balance or potassium.
  • Patients should be normally hydrated and have an adequate oral intake of sodium. Significant hypokalaemia must be avoided since this suppresses aldosterone secretion (note that the effect on increasing oral sodium will be to considerably increase urinary potassium excretion).
  • Please contact the duty biochemist for details of required patient preparation prior to performing this investigation.

Plasma Renin Activity

  • Plasma Renin Activity is sometimes assayed in isolation, usually in patients with known congenital adrenal hyperplasia or Addison's who are being monitored for adequacy of mineralocorticoid replacement.

Sample requirements

Please note that all samples must remain at room temperature (do not chill) and be delivered immediately to the laboratory.

For adults, blood taken into a 4ml EDTA Tube

EDTA with cap


For children, blood taken into a 2ml EDTA tube

2ml EDTA tube


For neonates, blood taken into a 1mL EDTA minicollect tube

1.0ml minicollect EDTA tube


Storage/transport

Do not store samples for either Aldosterone:Renin Ratio and Plasma Renin Activity. Deliver immediately to the laboratory at room temperature (do not chill).

Required information

For both Aldosterone:Renin Ratio and Plasma Renin Activity, please include relevant clinical details, including current anti-hypertensive medication. If current medication is not provided, analysis may be delayed as this is required before samples can be referred.

Turnaround times

Samples for Aldosterone:Renin Ratio are sent once a week by courier for analysis at Kings College Hospital London, with results expected back within 3 weeks.

Samples for Plasma Renin Activity are sent once a week by courier for analysis at Charing Cross, with results expected back within 5 weeks.

Reference ranges

Aldosterone:Renin Ratio

Renin (mU/L): Upright 5.4 - 60, Supine 5.4 - 30

Aldosterone (pmol/L): Upright 100 - 800, Supine 100 - 450

ARR: <80: Conn’s unlikely, ≥200: Conn’s likely, 80-200: Conn’s not excluded

Renin Activity

Adult (random) = 0.5-3.5 nmol/L/h

For paediatric patients, appropriate range will be given with the test results

Further information

To learn more about aldosterone and renin visit Lab Tests Online

Page last updated: 02/06/2023

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