During the history taking and physical examination, several important diseases should be searched for before diagnosing essential hypertension. A critical investigation is repetitive abdominal auscultation for a bruit. In young patients with significant hypertension, coarctation of the aorta must be excluded by clinical examination. Investigations will especially be aimed at uncovering renal artery disease (relatively common) or a phaechromocytoma (relatively rare). The initial assessment must also diagnose associated diseases which will influence the type of therapy chose. Thus asthma and heart failure contraindicate beta-blockers, liver disease contraindicates methyldopa, severe depression contraindicates reserpine, methyldopa and beta-blockade, while diabetes or gout may be precipitated or aggravated by thiazide diuretics.