Angiotensin I

Clinical Significance
Angiotensin I is a ten amino acid peptide formed by Renin cleavage of Angiotensinogen (Renin Substrate) I.   Angiotensin I has little biological activity except that high levels can stimulate Catecholamine production. It is metabolized to its biologically active byproduct Angiotensin II by Angiotensin Coverting Enzyme (ACE). The formation of Angiotensin I is controlled by negative feedback of Angiotensin II and III on Renin release and by Aldosterone concentration. Levels of Angiotensin I are increased in many types of hypertension. Angiotensin I levels are used to determine Renin Activity. Angiotensin I is excreted directly into the urine.

Reference Range
Up to 25 pg/mL.

Angiotensin I is measured by direct EIA/ELISA.

Patient Preparation
Patient should be on a normal sodium diet, 110 mEq. sodium.  Patient should be in a recumbent posture for at least 30 minutes prior to collection of specimen.  Diuretics, mineralocorticoids, glucocorticoids, estrogens, oral contraceptives, and ACTH medications and sodium, potassium, and posture all affect Angiotensin levels.

Specimen Collection
3 ml EDTA plasma should be collected and separated as soon as possible.  Freeze plasma immediately after separation.  Minimum specimen size is 1 ml.

Special Specimens
For tumor/tissue and various fluids (i.e. CSF, peritoneal, synovial, etc.), contact the Institute for requirements and special handling.

Shipping Instructions
Ship specimens frozen in dry ice.

1. van Hooft IMS, Grobbee DE, Derkx FHM, et al.  Renal Hemodynamics and the Renin-Angiotensin-Aldosterone System in Normotensive Subjects with Hypertensive and Normotensive Patients.  N Engl J Med 324:1305-1311, 1991.

2. Oparia S and Haber E. The Renin-Angiotensin System. N Engl J Med 291:389, 1974.

CPT Code: 
Immunoassay  83519