Blood Pressure Classification

Blood pressure classification: SBC 2024 vs AHA cut-offs

Resting blood pressure gets staged from a systolic (SBP) and diastolic (DBP) reading in mmHg, and when the two land in different bands you take the higher one. Here are the SBC 2024 bands (Brazilian Society of Cardiology): Optimal <120/80; Normal 120–129/80–84; Elevated 130–139/85–89; Stage 1 HTN 140–159/90–99; Stage 2 HTN ≥160/100; Isolated systolic HTN SBP ≥140 with DBP <90. AHA/ACC 2017 draws the lines lower, so ≥130/80 already counts as Stage 1 hypertension. As an example, 132/86 reads as Elevated under SBC but Stage 1 HTN under AHA.

Clinical context

An office reading mainly tells you who should get out-of-office confirmation through ABPM (24-hour ambulatory) or HBPM (home self-measurement), which weeds out white-coat and masked hypertension. You confirm HTN with two visits showing elevated office readings, or with ABPM means of ≥130/80 (24h), 135/85 (awake), or 120/70 (asleep). The stage you land in then steers when drugs start, what target to aim for (often <130/80 in high-risk patients), and how you stratify cardiovascular risk alongside SCORE2 or Framingham.

FAQ

Why do SBC and AHA differ? SPRINT (2015) found a benefit at lower SBP targets, which pushed AHA to drop its diagnostic cut-off to 130/80. SBC stuck with 140/90 for diagnosis but still recommends targets <130/80 in plenty of groups, so the actual treatment ends up looking much the same.

How to measure correctly? Sit for 5 min with your back supported, feet flat and arm at heart level, skip caffeine and smoking for the 30 min before, then average 2 readings taken 1–2 min apart, checking both arms the first time round.

What is hypertensive urgency vs emergency? A severe spike (≥180/120) with no target-organ damage counts as urgency. Once there's acute damage in the picture (stroke, ACS, pulmonary edema, eclampsia, aortic dissection), it becomes an emergency that needs IV therapy.

Pediatric thresholds? Don't use the adult cut-offs here. Go by age/sex/height percentile tables (AAP 2017), where HTN means ≥95th percentile, or ≥130/80 in adolescents ≥13 y.