Plasma Renin Activity (PRA) Activity Renin Plasma • •

Alphabetical Test Section 10537X Low Low High eful in evaluating erization studies, Analytical sensitivity: 0.37 ng/mL/h Angiotensin I generation, radio- immunoassay (RIA) • Specimen Requirements plasma EDTA 3 mL frozen 0.4 mL minimum refrigerated temperatures.Avoid When submitting cathet 1°aldosteronism Low Hyporeninemic High Low hypoaldosteronism Renin AldosteronePotassium Low Method • the at sample each of a portion retain referring laboratory. Patient preparation: moderate sodium no ambulatory 30 minutes; for diet; medications,3 weeks preferably for collection. sample to prior Renin is a proteolytic produced enzyme is modulated Secretion by the kidney. Erect blood flow. renal in by changes hemor- posture, sodium depletion, cardiacand low output all rhage, increase renin reducing secretion by flow. of plasma renin measurement The activity (PRA) us is Clinical Background hypertension. Primary hyperaldos- teronism is associated with sodium retention, increased blood volume, and low renal blood flow, increased PRA rules high or Thus, a normal PRA. out primary aldosteronism. Conversely, a normal or low PRArule helps out an Additionally, renal hypertension. elevated PRA may indicate renovascular hypertension due to renal artery stenosis. The interpretation of PRA values is facilitated by measurementsof aldosterone and serum potassium levels. 137 – –

0.65 >1.5 15.0 17.0 16.0 16.0 <0.65 >10.0 > <0.65 rd 1/3 1976;89:256; 1976;89:256;

Eur J Pediatr. J Eur †† 5.95.34.4 < < < 7.5 < 15.0 10.0 sis of hypertension egnant individuals egnant individuals J Pediatr. Supine Upright § † 1979;13:817; and and 1979;13:817; Essential hypertension ( hypertension Essential Primary aldosteronism Hyporeninemic hypo- Hyporeninemic Medications (eg, diuretics, diuretics, (eg, Medications Secondary hypoaldosteronism Addison’s disease Addison’s Renal hypertension Renal aldosteronism ACE inhibitors) ACE of cases; PRA <0.65 ng/mL/h) PRA <0.65 of cases; • • • • • • • possible tension likely tension possible tension more likely tension tension likely tension In ambulatory, briefly seated hypertensive briefly seated In ambulatory, 7-9 y y10-12 y13-15 < < < Primary aldosteronism Sodium/volume hyper- Sodium/volume hyper- Renovascular hyper- Renovascular SupineUprightUpright/sitting 0.65-5.0 0.3-3.0 0.4-8.8 Assess renin-aldosterone axis Differentialdiagno Renin-mediated hyper- Renin-mediated 3-12 mo3-12 < 1-3 y4-6 y < < To be used in conjunction with aldosterone be used in To Pediatricfrom data Clinical Cut-off Values Cut-off Clinical concentration; this concentration; condition. is a rare 1994;153:284. Pediat Res. § † †† *In apparently healthy, non-hypertensive, non-hypertensive, *In apparently healthy, non-pr non-medicated, on unrestricteddiets.on Adults* ng/mL/h ng/mL/h Children patients. Interpretive Information Interpretive Reference Range Reference Clinical Use Plasma Renin Activity (PRA) Activity Renin Plasma • •