Aldosterone and Renin Activity

Blood Sciences Test

SPECIMEN

EDTA (must be received within 6 hr of sample collection). Do not send sample on ice.

Instructions

Taken From:

Endocrinology Handbook

Endocrine Unit

Imperial College Healthcare NHS Trust

Charing Cross, Hammersmith and St. Mary’s Hospitals

Updated: March 2010

INDICATIONS

Accelerated hypertension.
Drug resistant hypertension
Hypertension and adrenal incidentaloma
Hypertension with hypokalaemia, spontaneous or easily provoked, i.e. by diuretics or sodium loading – consider if plasma potassium is <3.6 mmol/L. As the treatment of hyperaldosteronism is far more effective in correcting hypokalaemia rather than the hypertension extensive investigation in normokalaemic patients is not justified.

FIRST LINE INVESTIGATION OF PRIMARY HYPERALDOSTERONISM (CASE DETECTION):

It is important to remember that normokalaemic hypertension constitutes the most common presentation of this disease. Therefore, hypokalaemia alone has a low positive predictive value for primary hyperaldosteronism.

CONTRAINDICATIONS

None

SIDE EFFECTS

None

PROCEDURE: RANDOM ALDOSTERONE/RENIN RATIO (ARR)

Outpatient procedure

Stop beta blockers for 2 weeks prior to the sample, as beta blockers prevent renin release and stop spironolactone 6 weeks before sample.

Other drugs need not be stopped unless further investigations are required (see below)

Supply details of all therapy on request form

Ensure adequate salt intake – NOT loading

Correct severe hypokalaemia (<3.0 mmol/L) first, as a low potassium directly will reduce aldosterone secretion.

Method

Sit patient quietly for at least 10 minutes

1 X EDTA samples (7.5 ml red top)

Send to lab (must be received within 6 hr of sample collection). Do not send sample on ice.

INTERPRETATION OF RESULTS: For tests performed at Referral Laboratory University Hospital Southampton

ARR <91: An aldostorone:renin ratio of <91 pmol/mU makes a diagnosis of primary aldosteronism unlikely (Endocrine Society Clinical Practice Guideline 2016).

Hypokalaemia must be corrected prior to sampling as low potassium reduces aldosterone secretion.

Doxazosin, verapamil (slow release) and hydralazine are the only antihypertensive drugs that do not significantly affect the aldosterone:renin ratio.

ARR ≥91: Aldosterone/renin ratio >91 pmol/mU consistent with primary aldosteronism, further follow up advised.

ARR ≥91, but aldosterone < 280 pmol/L: Although aldosterone/renin ratio >91 pmol/mU the absolute aldosterone concentration makes primary aldosteronism unlikely.

REFERENCES

Rossi GP et al Prospective evaluation of the saline infusion test for excluding primary hyperaldosteronism due to an aldosterone producing adenoma. Journal of Hypertension 25:1433-1442

Funder JW et al Primary hyperaldosteronism guidelines: Case detection, diagnosis and treatment of patient with primary hyperaldosteronism: An Endocrine Society Clinical Practice Guideline. JCEM Epub ahead of print Jun 13

AVAILABILITY

Referred test to University Hospitals Southampton

Specimen Labelling Procedure