CPT Code:


Test Type: 3 mL Plasma, frozen
Stability Time:



Room temperature

1 hour


1 hour


14 days

Freeze/thaw cycles

Stable x3



The renin-angiotensin aldosterone hormonal cascade that regulates blood pressure and water (fluid) balance begins with the biosynthesis of renin by the juxtaglomerular cells that line the afferent (and occasionally efferent) arteriole of the renal glomerulus.1,2 A drop in blood pressure decreases the perfusion of the juxtaglomerular apparatus, resulting in the release of the enzyme renin. Renin proceeds to cleave angiotensinogen to produce angiotensin I. Angiotensin I is in turn converted to angiotensin II by angiotensin-converting enzyme (ACE), which is found mainly in lung capillaries. Angiotensin II is the major bioactive product of the renin-angiotensin system, binding to receptors on intraglomerular mesangial cells, causing these cells to contract along with the blood vessels surrounding them and causing the release of aldosterone from the adrenal cortex. Angiotensin II has multifaceted effects on aldosterone secretion, vasoconstriction, sodium reabsorption, and fluid volume, all of which serve to raise blood pressure. Laboratory studies with cultured cardiomyocytes have implicated angiotensin as a direct cause of left ventricular hypertrophy associated with hypertension. Angiotensin II also inhibits renin release by the kidney via a feedback mechanism.

Several investigators have found that a subgroup of patients with severe chronic heart failure has elevated plasma angiotensin II levels despite long-term ACE inhibitor use.3,4 This phenomenon has been referred to as ACE escape or angiotensin II reactivation and has been associated with increased mortality.4-7

Results for this test are for research purposes only by the assay's manufacturer. The performance characteristics of this product have not been established. Results should not be used as a diagnostic procedure without confirmation of the diagnosis by another medically established diagnostic product or procedure.

1. Atlas SA. The renin-angiotensin system: Pathophysiological role and pharmacologic inhibition. J Manag Care Pharm. 2007; 13(8 Suppl B):9-20. PubMed 17970613

2. Reudelhuber TL, Bernstein KE, Delafontaine P. Is angiotensin II a direct mediator of left ventricular hypertrophy? Time for another look. Hypertension. 2007; 49(6):1196-1201. PubMed 17452509

3. Roig E, Pérez-Villa F, Morales M, et al. Clinical implications of increased plasma angiotensin II despite ACE inhibitor therapy in patients with congestive heart failure. Eur Heart J. 2000; 21(1):53-57. PubMed 10610744

4. van de Wal RM, Plokker HW, Lok DJ, et al. Determinants of increased angiotensin II levels in severe chronic heart failure patients despite ACE inhibition. Int J Cardiol. 2006; 106(3):367-372. PubMed 16337046

5. MacFadyen RJ, Lee AF, Morton JJ, et al. How often are angiotensin II and aldosterone concentrations raised during chronic ACE inhibitor treatment in cardiac failure? Heart. 1999; 82(1):57-61. PubMed 10377310

6. Athyros VG, Mikhailidis DP, Kakafika AI, et al. Angiotensin II reactivation and aldosterone escape phenomena in renin-angiotensin-aldosterone system blockage: is oral renin inhibition the solution? Expert Opin Pharmocother. 2007 Apr; 8(5):529-535. PubMed 17376010

7. Chinnaiyan KM, Alexander D, McCullough PA. Role of angiotensin II in the evolution of diastolic heart failure. J Clin Hypertens (Greenwich). 2005; 7(12)740-747. PubMed 16330897

Collection Details:

Patient Preparation:

Patient must not have received radioactive substances 24 hours prior to test. Patient should be fasting.

Collection Instructions:

Contact the LabCorp supply department for collection kit.

Lavender-top (EDTA) tube with Trasylol®.

Trasylol® kits may be ordered through the PeopleSoft system (LabCorp N° 33328). Using a chilled 6-mL lavender-top (EDTA) tube taken from the kit, collect a whole blood specimen. Mix the specimen several times by inverting the EDTA collection tube. After removing the cap from the EDTA draw tube, take one of the sterile, Beral pipettes (from under the gray foam), and add 0.25 mL Trasylol® to the EDTA tube. Recap the EDTA tube and invert several times to mix well. Centrifuge the EDTA tube to separate the plasma from the cells, and immediately transfer the plasma into one of the brown screw-cap transfer tubes provided in the kit. There should be a "Trasylol® Added" label affixed to the brown transport tubes. Cap and freeze the labeled transport tube containing the EDTA plasma with Trasylol® added. To avoid delays in turnaround time when requesting multiple test on frozen samples, please submit separate frozen specimens for each test requested.