To screen for primary hyperaldosteronism. Suggested candidates for screening:

1. Patients with hypertension, hypokalemia and resistant hypertension.

2. Young hypertensive (age <40)

3. Patients with adrenal incidentaloma.

The renin-aldosterone axis is primarily regulated by renal blood flow. Subjects under investigation should, therefore, not be taking any drugs that interfere with fluid balance or potassium.

Plasma, 3ml x 2 

Two (2) ETDA tubes (To fill up to marked level on tube)

1. Only single form is required for the test. 

2. Patient’s clinical, drug history and latest potassium level are mandatory.

3. Record patient’s posture whether supine or upright:

   • Supine sample: Sample taken in the early morning before subject arises (if feasible)

   • Upright sample: Subject should be upright for ≥ 2 hours prior to sampling.

4. Test should be requested by Specialist/Endocrine Specialist only.

1. Attempt to correct hypokalemia

• Blood should be collected slowly with syringe and needle (preferably not vacutainer to minimize the risk of spuriously raising potassium).

  1. • Avoid first clenching – wait at least 5 seconds after tourniquet release to insert needle.

     • Send to lab as soon as possible after collection for plasma separation 

• Avoid hypokalaemia as it suppresses aldosterone secretion. Give potassium replacement (slow K tabs) sufficient to raise plasma potassium >4.0 mmol/L. Replacement should be stopped on the day of blood collection.

2. Subject should be normally hydrated and has an adequate oral intake of sodium.

3. Drugs to avoid: 

• Spironolactone (MUST BE STOPPED FOR 6 WEEKS)

• Amiloride

• Triamterene

• Potsssium wasting diuretics

• Product derive from licorice roots 

4. If ARR testing is not diagnostic after withdrawing above agents and hypertension can be controlled with noninterfering medications, test again 2 weeks after withdrawing other medications

• ACE inhibitors, ARB, beta-blockers, methyldopa, clonidine

• Oral contraceptives and hormone replacement therapy may lower direct-renin and cause false positive ARR: Do not withdraw unless confident of alternative effect contraception.

5. Drugs that DO NOT INTERFERE with the renin – aldosterone axis include Prazosin, verapamil, hydralazine and terazosin.

1. Sample should be taken between 8am to 10am. 

   1. • Supine sample: Sample taken in the early morning before subject arises (if feasible).

      • Upright sample: Subject should be upright for ≥ 2 hours and seated for 5-15minutes prior to sampling.

2. Collect sample carefully into 2 tubes of ETDA to avoid stasis and hemolysis.

3. Blood sample should be sent rapidly to the laboratory at room temperature within 30 minutes for centrifugation. Do not send sample in ice as cooling would cause cryoactivation of prorenin to renin, leading to falsely raised renin.

Upon Arrival

1. Separate plasma (Renin Or  Aldosterone) immediately

2. Transfer the plasma into a plastic / secondary tube

3. Minimum volume for plasma Renin and plasma Aldosterone is 500µl of PLASMA EACH.

4. Plasma should be frozen as soon as possible (-20oC or below).

5. Sample tube should each have the following information (barcode or manual labeled):

   • Requested test

   • Patient’s name 

   • Identity card number / medical registration number (MRN)

   • Date of collection

Transportation of Sample

1. Sample should be sent FROZEN, packed in ice and place in sturdy insulated container.

2. Sample not received in optimum condition shall be rejected.

Causes of Rejection:

• Wrong container

• Insufficient sample 

• Haemolysis or lipaemic sample

• Incorrect patient preparation

• Incomplete request form

• Incomplete patient information

• No test indication / no clinical history

• No requesting doctor’s name and signature

Sample Stability: 60 days at -20oC 

Protocol for Requesting and Collecting for Plasma Renin and Plasma Aldosterone, Department of Pathology, Hospital Putrajaya.