Renin Activity, Plasma

Single-analyte tests

• Renin Activity, Plasma 002006

  Plasma · Fasting not stated · Turnaround 4 - 7 days

  Method and collection

  Method

  The renin in plasma is allowed to act on the plasma's endogenous substrate, angiotensinogen producing angiotensin I. This is measured by liquid chromatography/mass spectrometry (LC/MS-MS).

  Preparation

  In order to facilitate interpretation of test results, the patient should be taken off medications for at least three weeks prior to sample collection (see Limitations for details). Dietary sodium levels during the period prior to testing can affect renin levels. Sodium restriction tends to cause an increase in renin activity, while supplementation can result in lower values. A 24-hour urine sodium determination from a sample collected on the day before a renin test can be used to assess sodium intake. Since patient posture prior to collection affects renin levels, it is recommended that the patient be ambulatory for at least 30 minutes before blood collection.1 If inpatients are physically able, they should be asked to ambulate for 30 minutes before blood is drawn for renin activity.

  Collection

  Draw blood into an EDTA tube. Keep tube at room temperature. Centrifuge at room temperature.1 Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. It is critical that the plasma be transferred and frozen as quickly as possible to prevent cryoactivation of protein to renin (which results in falsely elevated renin levels). To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.

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Panels that include this biomarker

• Aldosterone:Renin Ratio 004354

  3 analytes · Serum · Fasting not stated · Turnaround 4 - 7 days

  Method and collection

  Method

  Liquid chromatography/tandem mass spectrometry (LC/MS-MS)

  Preparation

  Patients should be instructed to maintain an unrestricted dietary salt intake prior to testing. Washout of all interfering antihypertensive medications may be considered in patients with mild hypertension but is potentially problematic in others and perhaps unnecessary in that medications with minimal effect on the ARR can be used in their place. The patient should not take drugs that markedly affect the ARR for at least four weeks prior to blood collection. These drugs include: • Spironolactone, eplerenone, amiloride, and triamterene • Potassium-wasting diuretics • Products derived from licorice root (e.g., confectionary licorice, chewing tobacco) More details can be found in the Endocrine Society clinical practice guideline.1

  Collection

  Collect blood mid-morning, after the patient has been up (sitting, standing, or walking) for at least two hours and seated for 5 to 15 minutes. Refer to descriptions for individual tests Renin Activity, Plasma [002006] and Aldosterone, LC/MS [004374] for more detailed preparation and test collection information. After collection, immediately centrifuge the lavender-top tube at room temperature, transfer plasma to a transport tube, and freeze . Label this tube "Frozen Plasma−Renin." If a red-top tube is used, transfer separated serum to a plastic transport tube. Label the serum tube "Serum−Aldosterone." To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.

  Reference notes

  0.0−30.0 ng/dL per ng/mL/hour

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Single-analyte tests

• Plasma Renin Activity with Reflex to Aldosterone 13817

  Plasma · Fasting not stated · Turnaround Set up: Sun-Fri

  Method and collection

  Method

  Chromatography/Mass Spectrometry

  Collection

  Collection is not limited to mid-morning; patient needs to sit 5-15 minutes prior to collection

  Reference notes

  See Laboratory Report

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• Plasma Renin Activity, LC/MS/MS 16846

  Plasma · Fasting not stated · Turnaround Set up: Mon-Fri; Report available: 5 days

  Method and collection

  Method

  Chromatography/Mass Spectrometry

  Collection

  Collect a mid-morning blood sample after patient has been upright (sitting, standing, or walking) for a minimum of 2 hours, then have them sit 5-15 minutes prior to collection.

  Reference notes

  0.25-5.82 ng/mL/h

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