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Test ID: Renin (activity, plasma)
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Renin (activity, plasma)
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Renin (activity, plasma)
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Useful For
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The investigation of the function of the renin-angiotensin-aldosterone system
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Method name and description
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Enzyme-linked immunosorbent assay (ELISA)
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Clinical information
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Renin is an enzyme that forms part of the renin-angiotensin-aldosterone system (RAAS), which is involved in the homeostatic control of the circulatory volume and electrolyte balance. Disturbances in the RAAS can lead to hypertension, such as in primary aldosteronism, or hypotension, such as in aldosterone synthase deficiency.
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Aliases
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Plasma renin activity
PRA
Renin activity
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Specimen type / Specimen volume / Specimen container
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Specimen type: Blood (plasma).
Specimen Volume: 0.5 mL plasma.
Specimen container: EDTA tube
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Collection instructions / Special Precautions / Timing of collection
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The patient should have been in an erect position (sitting, standing, or walking) for at least 2 hours before blood sampling.
Sample should be collected after the patient has rested in a seated position for 15 minutes, preferably in the morning.
If aldosterone is to be measured, such as for the investigation of primary aldosteronism, the aldosterone sample must be collected at the same time.
The blood sample must be sent to the lab within one hour for separation and storage, if the sample transfer to the lab will be delayed for any reason or in case of sample receipt after section working hours the sample should be spun at 2000 g for 15 minutes in an unrefrigerated centrifuge, separated and plasma frozen (at -20 °C) within one hour of collection and delivered to the section frozen.
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Relevant clinical information to be provided
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Presenting clinical signs and symptoms
Any relevant medications, particularly antihypertensives
If part of a dynamic test, the relative sample timing
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Storage and transport instructions
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Blood sample should be transported at room temperature (20 - 30˚C) and should reach the laboratory within one hour of collection time.
If the sample transfer to the lab will be delayed for any reason or in case of sample receipt after section working hours the sample should be spun at 2000 g for 15 minutes in an unrefrigerated centrifuge, separated and plasma frozen (at -20 °C) within one hour of collection and delivered to the section frozen.
Separated plasma samples may be stored for up to 30 days frozen at -20 °C. The sample should not be thawed till analysis.
Samples should be transported according to their storage conditions.
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Specimen Rejection Criteria
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Clotted, grossly haemolysed, lipaemic, icteric plasma, and any sample that was not handled properly according to the instruction.
Insufficient sample volume.
Refrigerated sample.
Bacterial contaminations, repeated freeze and thaw cycles and dilution of plasma samples may affect the assay result.
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Biological reference intervals and clinical decision values
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0.29 – 6.12 ng/mL/hr
Plasma renin activity is often interpreted alongside a concurrent aldosterone measurement.
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Factors affecting test performance and result interpretation
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Antihypertensive medications, salt balance, and posture can alter the level of renin measured and results should always be interpreted with appropriate considerations.
Samples exposed to freeze/thaw cycles or refrigeration may give higher plasma renin activities due to cryoactivation of prorenin.
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Turnaround time / Days and times test performed / Specimen retention time
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Turnaround time: 5 working days.
Days and times performed: weekly, usually on Wednesday.
Specimen retention time: 7 days.
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