Angiotensin II is an eight amino acid peptide formed by angiotensin-converting enzyme (ACE) from the breakdown of angiotensin I. Angiotensin II is further metabolized to angiotensin III. Angiotensin II release is controlled by renin, blood pressure, blood volume, sodium balance, and aldosterone concentration.
Angiotensin II levels are increased in many types of hypertension. Angiotensin II stimulates the release of antidiuretic hormone, ACTH, prolactin, luteinizing hormone, oxytocin, and aldosterone. Angiotensin II increases vasoconstriction and inhibits renal tubular sodium reabsorption and may stimulate endothelial cell growth.
Medications such as diuretics, corticosteroids, glucocorticoids, estrogens, oral contraceptives, adrenocorticotropic hormone, sodium, potassium, as well as posture during blood sampling, affect angiotensin II levels.