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Renin
minimum sample volume required ~ 4ml
Test Code: REN
Tube type: EDTA
Other acceptable tube types
Lithium heparin (pale green) also accepted but EDTA preferred
Special instructions
Samples must be transported to the lab at room temperature. DO NOT TRANSPORT CHILLED ON ICE.
MUST be received in lab within 4 hours of collection.
Sample time MUST be stated on form.
Serum potassium must be >3mmol/L.
Sent away
to Charing Cross Hospital, London
Reference range
0.5 - 3.5
Units
nmol/L/hr
Linked to
Aldosterone
Turnaround Time
28
days
Department: Biochemistry
Clinical Application
Aldosterone:Renin ratio is useful in the investigation of hypertension, especially if resistant, persistent hypokalaemia (but note 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.
Plasma renin activity is sometimes assayed in isolation in patients who are being monitored for adequacy of mineralocorticoid replacement.
Interpretation of Aldosterone/Renin ratio (ARR):
Conn's unlikely: <680
Possible Conn's: >850
Conn's very likely: >1700
Webpage updated: June 2024
Links:
» Aldosterone and renin: guidance for investigation of primary hyperaldosteronism
