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PTD - 155

           Test Directory -  Aldosterone and Renin

Synonyms   

Clinical Indications

Investigation of suspected disorders of aldosterone production, for example primary hyperaldosteronism and hyporeninaemic hypoaldosteronism. Aldosterone / Renin ratio is used as a screening test (see screening protocol).

Request Form

Combined Pathology Blood form (Yellow/Black)

Availability

Referred test: Analysed by Biochemistry, Charing Cross Hospital if specific criteria met.

Specific Criteria

Studies will only be undertaken on In-patients if requested by Consultant Nephrologists / Endocrinologists or if agreed with Consultant Biochemist. Outpatient requests should only be undertaken on following:

1. Patients with severe hypertension who do not respond to two or more antihypertensives.
2. Hypertensives with hypokalaemia (and inappropriate urinary loss of potassium of >35 mmol/24hrs).
3. Diagnosis / differentiation between, primary and secondary causes of hyper- or hypoaldosteronsim.
4. Family history of hypertension.
5.

Management of renal artery stenosis (renin).

6.

Diagnosis and location of renin secreting tumours (renin).

Please ensure that all relevant clinical details (e.g. blood pressure) and current medication is noted on the request form. Failure to give adequate clinical information will delay sample analysis.It is imperative that Biochemistry are informed beforehand so that arrangements can be made for specimen handling.

Patient Preparation

This test should be performed as an out-patient procedure. There are a number of drugs that interfere with the aldosterone / renin axis.
Patients must attend Basildon phlebotomy for sample collection.
Ideally, samples should be collected in the morning after the patient has been out of bed for ≥2 hours and after sitting 5-15 minutes.

Turnaround Time

1 month

Specimen

Plasma and serum

Volume

2 ml (aldosterone) and 5ml (renin)

Container

    
7ml EDTA (purple top) tube and yellow top (SST)


  
For children less than 6 years of age a minimum of one full paediatric EDTA (red top) tube and one full paediatric Lithium Heparin (Orange top) tube should be collected.

Samples must be transported to the laboratory immediately.

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

Interpretation

Comprehensive interpretive comment is provided by referral laboratory

Lab Handling

Processing: Centrifuge and aliquot immediately into 3 tubes and freeze at    -20C in separating freezer (CB40), active frozen rack 110.
Referral: ALD and send or NOALD and save in separating freezer (CB40), at -20C in the saved frozen rack.
     

Version 1.0 / April 2014                                                                                                          Approved by: Consultant Biochemist