Clinical Indications

Investigation of primary hyperaldosteronism. Aldosterone / Renin ratio is used as a screening test (out-patient procedure) and, if equivocal may be followed up using overnight recumbency (in-patient procedure).

Request Form

Combined Pathology Blood form (Yellow/Black)

Availability

Analysed by referral laboratory if specific criteria met.

Specific Criteria

Requested by Consultant Renal Physicians or if agreed with Consultant Biochemist. Investigation will normally only be undertaken if patient has persistent hypokalaemia (< 3.5 mmol/l) and inappropriate urinary potassium loss (> 35 mmol/24hr).

Patient Preparation

Drugs that interfere with the aldosterone / renin axis must be discontinued for 2 weeks prior to testing. Patients must attend Basildon phlebotomy for sample collection.

Turnaround Time

1 month

Specimen

Plasma

Volume

2 ml (aldosterone) and 5ml (renin)

Container

2 PLASTIC orange top (lithium heparin) tubes

Collection

Samples must be transported to laboratory immediately.

Lab. Handling

Mix and centrifuge immediately, and transfer plasma to a second PLASTIC tube. Freeze 3 aliquots (2 to be sent)..

Causes for Rejection

Not meeting specific criteria for analysis. Delay in sample reaching laboratory.

Reference Range

If the ratio of aldosterone (pmol/l) to renin (pmol/ml/h) is greater than 2,000, the patient almost certainly has primary hyperaldosteronism