Renin is a proteolytic enzyme released from juxtaglomerular cells of the kidney. The enzyme cleaves a substrate to produce Angiotensin I which in turn produces Angiotensin II. This metabolite plays a key role in various forms of hypertension. Investigation of primary aldosteronism (eg, adrenal adenoma/carcinoma and adrenal cortical hyperplasia) and secondary aldosteronism (renovascular disease, salt depletion, potassium loading, cardiac failure with ascites, pregnancy, Bartter syndrome)