Aldosterone and renin

Alternative names, keywords

Renin activity, PRA, aldosterone: renin ratio, ARR

Samples required

● EDTA blood (purple cap/ yellow cap ring, 4 mL tube). Smaller tubes are available for paediatric samples.

Bring to lab for immediate attention (plasma must be separated within 4h). Renin and aldosterone can both be done on the same EDTA sample.

State drug treatment (see below), BP, recumbency if known.

Test indications

Aldosterone:  moderate/severe hypertension, hypertension with spontaneous / diuretic-induced hypokalaemia, especially if sodium ≥140 mmol/L, hypertension refractory to 3 or more drugs, young hypertensives, hypertension in presence of incidental adrenal adenoma, hypertension with obstructive sleep apnoea.

PRA: diagnosis of and differentiation between primary and secondary hyper- and hypo-aldosteronism, monitoring mineralocorticoid replacement therapy, management of renal artery stenosis, diagnosis and location of renin-secreting tumour.

Test information

Guidance on medication provided by the analysing laboratory:

• If clinically safe to do so, the minimal recommended medication removal is to stop beta-blockers, central α2-agonist and NSAID therapy for two weeks as these may cause false positive results.
• Samples for suspected primary aldosteronism should be tested before mineralocorticoid receptor antagonists are started (or stopped for at least four weeks, preferably six along with K-sparing diuretics).
• It may also be helpful to remove ACEi/A2RB, CCB and diuretics for two weeks, K-wasting diuretics for four.
• Antihypertensives that have minimal effect on aldosterone and renin include the alpha blockers (e.g. doxazosin) or non-dihydropyridine calcium channel blockers (e.g. verapamil).
• Whilst aldosterone/renin mass ratios are affected by oestrogens and menstrual cycle, aldosterone/renin activity ratios are less affected.

Reference range

Turnaround time

Referral lab quotes turnaround time of 22 working days, however additional time must be allowed for packing, dispatch and delivery of sample, and return and processing of results.

Enquiries

Biochemistry (Referrals)