Evaluation of patients for secondary hypertension

The recognition of secondary causes of hypertension, such as renovascular disease and aldosteronism, can be enhanced by stimulation and suppression of the 2 limbs of the renin angiotensin system. Normal values have been established in unstimulated and stimulated conditions. Saline infusion suppresses plasma aldosterone normally. Patients with proved adenomas do no suppress renin and are outside the well established ranges of normal suppression. Likewise, furosemide will stimulate renin release. Patients with proved aldosteronism are outside the normal ranges of plasma renin activity. These maneuvers also are useful in discriminating renovascular hypertension, particularly when achieving differential renal venous collections under stimulated conditions (after furosemide and tilting). By stressing this system (with furosemide stimulation or saline suppression) one can discriminate better secondary hypertension by the failure to respond normally.