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Renin activity

Test/Range/Collection

Renin activity, plasma (PRA)

Lavender

Salt-depleted, upright: 3.0–15 ng/mL/hr

Salt-replete, upright: 0.6–3.0 ng/mL/hr

(age-dependent)

$$

Physiologic Basis

The renal juxtaglomerular apparatus generates renin, an enzyme that converts angiotensinogen to angiotensin I. Renin secretion by the kidney is stimulated by a decrease in glomerular blood pressure, decreased sodium at the renal distal tubule, or renal vascular disease.

The inactive angiotensin I is then converted to angiotensin II, which is a potent vasopressor.

Renin activity is measured by the ability of a patient’s plasma to generate angiotensin I from substrate (angiotensinogen), and expressed as ng/mL/hr.

Normal values depend on the patient’s hydration, posture, and salt intake.

Interpretation

Increased in: Dehydration, some hypertensive states (eg, renal artery stenosis), edematous states (cirrhosis, nephrotic syndrome, heart failure), hypokalemic states (gastrointestinal sodium and potassium loss, Bartter syndrome), adrenal insufficiency, chronic renal failure, left ventricular hypertrophy. Drugs: ACE inhibitors, estrogen, hydralazine, nifedipine, minoxidil, oral contraceptives.

Decreased in: Hyporeninemic hypoaldosteronism, some hypertensive states (eg, primary aldosteronism, severe preeclampsia). Drugs: β-blockers, aspirin, clonidine, prazosin, reserpine, methyldopa, indomethacin.

Comments

An elevated ratio of plasma aldosterone concentration (in ng/dL) to plasma renin activity (aldosterone-to-renin ratio or ARR) of 20 or higher is an effective screening test for primary aldosteronism (sensitivity, 95%). It has a high negative predictive value even during antihypertensive therapy. Because of a low specificity of the ratio, autonomous aldosterone production must be confirmed by demonstration of high and autonomous secretion of aldosterone (using an aldosterone suppression test). The ARR should be interpreted along with the actual values of aldosterone and plasma renin activity.

Plasma renin activity is also useful in evaluation of hypoaldosteronism (low-sodium diet, patient standing) (see Aldosterone, serum).

Weiner ID. Endocrine and hypertensive disorders of potassium regulation: primary aldosteronism. Semin Nephrol 2013;33:265.  [PMID: 23953804]

Zennaro MC et al. An update on novel mechanisms of primary aldosteronism. J Endocrinol 2015;224:R63.  [PMID: 25424518]

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Citation

McPhee, Stephen J., et al. "Renin Activity." Guide to Diagnostic Tests, 7th ed., McGraw-Hill Education, 2017. Medicine Central, im.unboundmedicine.com/medicine/view/GDT/619025/all/Renin_activity.
McPhee SJ, Lu CM, Nicoll D. Renin activity. Guide to Diagnostic Tests. 7th ed. McGraw-Hill Education; 2017. https://im.unboundmedicine.com/medicine/view/GDT/619025/all/Renin_activity. Accessed April 24, 2019.
McPhee, S. J., Lu, C. M., & Nicoll, D. (2017). Renin activity. In Guide to Diagnostic Tests. Available from https://im.unboundmedicine.com/medicine/view/GDT/619025/all/Renin_activity
McPhee SJ, Lu CM, Nicoll D. Renin Activity [Internet]. In: Guide to Diagnostic Tests. McGraw-Hill Education; 2017. [cited 2019 April 24]. Available from: https://im.unboundmedicine.com/medicine/view/GDT/619025/all/Renin_activity.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Renin activity ID - 619025 A1 - McPhee,Stephen J, AU - Lu,Chuanyi Mark, AU - Nicoll,Diana, BT - Guide to Diagnostic Tests UR - https://im.unboundmedicine.com/medicine/view/GDT/619025/all/Renin_activity PB - McGraw-Hill Education ET - 7 DB - Medicine Central DP - Unbound Medicine ER -