Accurate HTN diagnosis requires standardized measurement and exclusion of white coat and masked HTN. Office BP measurement must follow the AHA protocol: patient seated 5 minutes, back supported, feet flat, arm at heart level, bladder covering ≥80% of arm circumference, no caffeine/smoking for 30 minutes prior, empty bladder. Average ≥2 readings on ≥2 occasions confirms diagnosis. Out-of-office confirmation is recommended: ambulatory BP monitoring (ABPM) is the gold standard (24-hour mean ≥125/75, daytime ≥130/80, nighttime ≥110/65 confirm HTN). Home BP monitoring (HBPM) uses an average ≥135/85. White coat HTN (elevated office, normal ABPM/HBPM) occurs in 15-30% of patients and should be monitored but not necessarily treated. Masked HTN (normal office, elevated ABPM/HBPM) carries the same risk as sustained HTN and must be treated. Secondary HTN should be suspected when: onset before age 30 or after 55, resistant HTN (3 drugs including diuretic), sudden worsening of previously controlled HTN, severe/accelerated HTN, or clinical clues suggesting secondary cause. The most common secondary causes are: primary aldosteronism (5-10% of HTN; HTN + hypokalemia + metabolic alkalosis; screen with aldosterone-to-renin ratio), renovascular HTN (renal artery...