Hypertension

A single high reading is not, by itself, a diagnosis of hypertension. In Canada, the 2025 Hypertension Canada guideline defines hypertension as BP ≥130/80 mm Hg confirmed with out-of-office measurement, using home BP monitoring or ambulatory BP monitoring. Canada does not divide this diagnosis into stages. The 2025 US guideline retains staging, with stage 1 beginning at 130–139/80–89 mm Hg and stage 2 at ≥140/90 mm Hg, so exam questions must be interpreted in the jurisdiction being tested. Both guidelines target a systolic BP <130 mm Hg, alongside sodium reduction, physical activity, weight management, and limiting alcohol. The useful clinical model is BP = cardiac output × systemic vascular resistance, with cardiac output determined by heart rate × stroke volume. The rest of this lesson explains how the kidneys, RAAS, sympathetic nervous system, endothelium, and arterial wall shift those variables and sustain the elevation. That model also explains why treatment is mechanism-directed rather than based on the BP number alone. A very high pressure becomes a hypertensive emergency when new or worsening target-organ injury is present—not merely because the reading...