# Hypertension Diagnosis and Management

## Overview

Hypertension affects nearly half of US adults and is the leading modifiable risk factor for cardiovascular disease, stroke, and chronic kidney disease. Despite its prevalence, accurate diagnosis requires attention to proper measurement technique, and management continues to evolve as guidelines debate optimal treatment thresholds. Getting the basics right, starting with how blood pressure is actually measured, prevents both undertreatment and overtreatment.

## Blood Pressure Measurement

### Proper Office Measurement Technique

Accurate blood pressure measurement demands a consistent protocol. The patient should sit quietly for five minutes with feet flat on the floor, back supported, and the arm at heart level. The bladder should be empty. Caffeine, exercise, and smoking should be avoided within 30 minutes of the reading. Cuff size matters: the bladder should encircle 80% of the arm circumference, as an undersized cuff will falsely elevate the reading. The result should be the average of two to three readings taken one to two minutes apart. Automated oscillometric blood pressure devices (AOBP) are preferred over manual auscultation because they reduce the white-coat effect and eliminate observer bias.

### Out-of-Office Measurement

Ambulatory blood pressure monitoring (ABPM) is the gold standard for confirming a hypertension diagnosis. It provides 24-hour data including nocturnal readings and identifies dipping patterns, with hypertension defined as a daytime mean of 135/85 or higher or a 24-hour mean of 130/80 or higher. A non-dipping pattern, where blood pressure fails to decrease by at least 10% during sleep, is associated with increased cardiovascular risk. Home blood pressure monitoring (HBPM) is a practical alternative: using a validated device and proper technique, patients measure twice daily (morning and evening) for seven days, discarding the first day. The threshold for hypertension by HBPM is an average of 135/85 mmHg or higher.

### White-Coat and Masked Hypertension

White-coat hypertension, present in 15 to 30% of patients, occurs when blood pressure is elevated in the clinic but normal out of the office. Masked hypertension, affecting 10 to 15% of patients, is the opposite: normal office readings but elevated out-of-office values. Masked hypertension is clinically dangerous because it carries cardiovascular risk similar to sustained hypertension but goes undetected without out-of-office monitoring. Both patterns require out-of-office confirmation before making treatment decisions.

## Classification and Staging

### ACC/AHA 2017 Guidelines

The ACC/AHA 2017 guidelines classify blood pressure as normal (below 120/80 mmHg), elevated (120 to 129 systolic with diastolic below 80), stage 1 hypertension (130 to 139/80 to 89), stage 2 hypertension (140/90 or above), and hypertensive crisis (above 180/120).

| Category | Systolic (mmHg) | Diastolic (mmHg) |
|----------|----------------|-----------------|
| Normal | <120 | <80 |
| Elevated | 120-129 | <80 |
| Stage 1 Hypertension | 130-139 | 80-89 |
| Stage 2 Hypertension | ≥140 | ≥90 |
| Hypertensive Crisis | >180 | >120 |

### JNC 8 (2014) Treatment Thresholds

JNC 8 used different, generally more lenient thresholds: for the general population under 60, treatment at 140/90 or above targeting below 140/90; for those 60 and older, treatment at 150/90 or above targeting below 150/90; and for patients with diabetes or CKD, treatment at 140/90 or above targeting below 140/90.

### SPRINT Trial Impact

The SPRINT trial randomized high-risk, non-diabetic patients to intensive blood pressure control (target systolic below 120) versus standard control (below 140) and demonstrated a 25% reduction in composite cardiovascular events and 27% reduction in all-cause mortality with intensive treatment. However, the intensive group experienced higher rates of hypotension, syncope, acute kidney injury, and electrolyte abnormalities. An important nuance: SPRINT used automated unattended blood pressure measurements, which typically read 5 to 10 mmHg lower than standard office readings. Applying a target of below 120 based on conventional office measurements could lead to overtreatment.

## Secondary Hypertension Workup

### When to Suspect

Secondary hypertension should be considered when onset occurs before age 30 or after age 55, when hypertension is resistant to three or more medications including a diuretic, when previously controlled blood pressure suddenly worsens, when hypokalemia is present (suggesting aldosteronism), when an abdominal bruit is heard (suggesting renal artery stenosis), or when paroxysmal symptoms raise concern for pheochromocytoma.

### Common Secondary Causes

Primary aldosteronism is the most common secondary cause and is underdiagnosed. Screening involves measuring the aldosterone-to-renin ratio, with confirmation through salt-loading or fludrocortisone suppression testing. Renovascular disease presents as fibromuscular dysplasia in young women or atherosclerotic renal artery stenosis in older adults, diagnosed with CTA or MRA. Obstructive sleep apnea should be screened for with the STOP-BANG questionnaire and confirmed with polysomnography. Pheochromocytoma is diagnosed through 24-hour urine metanephrines or plasma free metanephrines. Cushing syndrome is screened for with 24-hour urine cortisol or an overnight dexamethasone suppression test. Thyroid disease requires TSH screening. Coarctation of the aorta presents with upper extremity hypertension, lower extremity hypotension, and rib notching on chest X-ray. Medication-related and substance-related causes include NSAIDs, decongestants, oral contraceptives, stimulants, alcohol, and cocaine.

## Pharmacotherapy

### First-Line Agents

Four drug classes are considered first-line for hypertension treatment.

| Drug Class | Examples | Key Indications | Major Side Effects |
|------------|----------|----------------|-------------------|
| Thiazide/thiazide-like diuretics | Chlorthalidone, HCTZ | General HTN, elderly, Black patients | Hypokalemia, hyperuricemia, hyperglycemia |
| ACE Inhibitors | Lisinopril, enalapril, ramipril | DM, CKD with proteinuria, HFrEF, post-MI | Cough, angioedema, hyperkalemia |
| ARBs | Losartan, valsartan, irbesartan | ACEi intolerance, same indications as ACEi | Hyperkalemia (no cough) |
| CCBs (dihydropyridine) | Amlodipine, nifedipine | Elderly, Black patients, isolated systolic HTN | Peripheral edema |

Thiazide and thiazide-like diuretics are effective, with chlorthalidone preferred over hydrochlorothiazide due to its longer half-life and superior outcomes data from the ALLHAT trial. Chlorthalidone is dosed at 12.5 to 25 mg daily, and monitoring should include potassium, sodium, uric acid, and glucose levels. ACE inhibitors (lisinopril, enalapril, ramipril) are first-line when there are compelling indications such as diabetes, CKD with proteinuria, HFrEF, or post-MI. Creatinine and potassium should be rechecked one to two weeks after initiation. ACE inhibitors are contraindicated in pregnancy, and angioedema risk is higher in Black patients. ARBs (losartan, valsartan, irbesartan) are an alternative when ACE inhibitor cough or angioedema develops, with the same indications and monitoring requirements; ACE inhibitors and ARBs should never be combined. Calcium channel blockers, with dihydropyridine agents (amlodipine, nifedipine) preferred for hypertension, are particularly effective in elderly patients, Black patients, and isolated systolic hypertension. Peripheral edema is the most common side effect. Non-dihydropyridine agents (diltiazem, verapamil) provide rate control but should not be combined with beta-blockers.

### Second/Third-Line and Add-On Agents

Beta-blockers are not recommended as first-line for uncomplicated hypertension but remain indicated for HFrEF, post-MI, and atrial fibrillation rate control. Spironolactone at 25 to 50 mg is the most effective add-on agent for resistant hypertension, as demonstrated in the PATHWAY-2 trial. Alpha-blockers (doxazosin) are useful in patients with concurrent BPH but carry orthostatic hypotension risk. Hydralazine combined with isosorbide dinitrate is particularly effective in Black patients with HFrEF, based on the A-HeFT trial. Clonidine, a central alpha-2 agonist, can cause rebound hypertension with abrupt discontinuation.

### Combination Therapy

Most patients require two or more agents to reach blood pressure targets. Combination therapy should be initiated upfront when blood pressure is 20/10 mmHg or more above goal. Effective combinations include ACE inhibitor or ARB with a calcium channel blocker, ACE inhibitor or ARB with a thiazide, or a calcium channel blocker with a thiazide. Combinations to avoid include ACE inhibitor with ARB and ACE inhibitor or ARB with a direct renin inhibitor.

## Resistant Hypertension

Resistant hypertension is defined as blood pressure remaining above goal despite three optimally dosed agents from different classes, one of which must be a diuretic. Before diagnosing true resistant hypertension, pseudo-resistance must be excluded by checking medication adherence (through pill counts and pharmacy refill records), verifying proper measurement technique, and ruling out a white-coat effect. For true resistant hypertension, the approach includes screening for secondary causes, optimizing the diuretic (switching to chlorthalidone if not already using it), and adding spironolactone. Referral to a hypertension specialist is appropriate if blood pressure remains uncontrolled on four or more agents.

## Special Populations

Black patients have a higher prevalence of hypertension with earlier onset and more target-organ damage. Calcium channel blockers and thiazide diuretics are preferred as initial therapy, while ACE inhibitors and ARBs are less effective as monotherapy in this population, though they remain indicated for compelling comorbidities. For patients with diabetes, a target below 130/80 is recommended, with ACE inhibitors or ARBs first-line when albuminuria is present. In CKD, the same target applies, with ACE inhibitors or ARBs for proteinuric disease and loop diuretics preferred when eGFR falls below 30. In pregnancy, safe options include labetalol, nifedipine, and methyldopa, while ACE inhibitors and ARBs are contraindicated. In elderly patients, therapy should be initiated cautiously with gradual titration, and standing blood pressure should be checked to assess for orthostatic hypotension before intensifying treatment.

<image>A step-by-step blood pressure measurement technique infographic showing proper patient positioning (seated, back supported, feet flat, arm at heart level), cuff size selection guide with arm circumference measurements, device placement on bare arm, and a checklist of pre-measurement requirements (5-minute rest, no caffeine, empty bladder). Include a side panel showing how to average readings.</image>

<image>A diagnostic algorithm flowchart for hypertension showing initial elevated office reading, confirmation with ABPM or HBPM, classification into white-coat HTN, masked HTN, or sustained HTN, followed by branching into primary vs. secondary workup based on clinical clues. Include boxes for each secondary cause with its corresponding screening test.</image>

<image>A comparison table formatted as an infographic showing the four first-line antihypertensive drug classes (thiazides, ACEi, ARBs, CCBs) with columns for mechanism, key indications, major side effects, monitoring requirements, and special population considerations. Use color coding to indicate compelling indications such as diabetes, CKD, HFrEF, and post-MI.</image>

## Clinical Pearls

Chlorthalidone is preferred over hydrochlorothiazide due to its longer duration of action and stronger evidence for cardiovascular outcomes reduction. When applying the SPRINT trial's intensive target of below 120 mmHg, it is critical to remember that the trial used automated, unattended blood pressure measurements that run 5 to 10 mmHg lower than typical office readings, so applying this target to standard office measurements risks overtreatment. Primary aldosteronism is substantially underdiagnosed and should be screened for in any patient with resistant hypertension or unexplained hypokalemia. Spironolactone is the most effective add-on for resistant hypertension, supported by the PATHWAY-2 trial. Orthostatic blood pressure should always be checked in elderly patients before intensifying therapy. ACE inhibitor-related cough occurs in up to 15% of patients, with higher rates in women and Asian patients, and switching to an ARB resolves the cough in nearly all cases. Single-pill combination therapy improves adherence compared to prescribing multiple separate pills.

## References

- Whelton PK et al. 2017 ACC/AHA Hypertension Guideline. J Am Coll Cardiol. 2018
- James PA et al. JNC 8: Evidence-Based Guideline for Management of High BP in Adults. JAMA. 2014
- SPRINT Research Group. A Randomized Trial of Intensive vs. Standard Blood-Pressure Control. NEJM. 2015
- Williams B et al. PATHWAY-2: Spironolactone vs. placebo, bisoprolol, and doxazosin for resistant HTN. Lancet. 2015
- ALLHAT Collaborative Research Group. JAMA. 2002
- Carey RM et al. Resistant Hypertension: Detection, Evaluation, and Management. Hypertension. 2018