What is white coat syndrome, also known as white coat hypertension, in adults with a history of hypertension or anxiety disorders?

White Coat Syndrome (White Coat Hypertension)

White coat syndrome is a condition where blood pressure is elevated in the medical office (≥140/90 mmHg or ≥130/80 mmHg by ACC/AHA criteria) but remains normal when measured outside the healthcare setting using home or ambulatory monitoring (<135/85 mmHg daytime or <130/80 mmHg 24-hour average). 1

Definition and Pathophysiology

White coat hypertension occurs due to an alerting response, anxiety, or conditioned response to the medical environment and physician presence. 1 This phenomenon affects 10-30% of patients attending clinics for elevated blood pressure, with higher prevalence in elderly patients, women, and non-smokers. 1

The key distinction is that office blood pressure readings are falsely elevated compared to the patient's true blood pressure during daily activities. 1

Diagnostic Criteria

Ambulatory blood pressure monitoring (ABPM) is the gold standard for confirming white coat hypertension, as it provides superior cardiovascular risk prediction compared to home monitoring. 1, 2

White coat hypertension is diagnosed when:

• Office BP ≥140/90 mmHg (or ≥130/80 mmHg per ACC/AHA 2017 guidelines) AND 1, 2
• Daytime ambulatory BP <135/85 mmHg OR 1, 2
• 24-hour ambulatory BP <130/80 mmHg OR 1, 2
• Home BP <135/85 mmHg 1, 2

When to Screen for White Coat Hypertension

Screen with ABPM or home monitoring in: 1

• Untreated adults with office SBP 130-159 mmHg or DBP 80-99 mmHg without diabetes, chronic kidney disease, or target organ damage
• Patients on multiple antihypertensive drugs with office BP within 10 mmHg of goal
• Any patient with persistently elevated office BP ≥140/90 mmHg before initiating treatment

Home blood pressure monitoring provides 60-70% overlap with ABPM for detecting white coat hypertension and serves as a reasonable screening tool when ABPM is unavailable. 1

Cardiovascular Risk Profile

White coat hypertension carries minimal to slightly increased cardiovascular risk compared to true normotensives—substantially lower than sustained hypertension. 1 However, compared to true normotensives, patients with white coat hypertension have: 1

• Higher out-of-office blood pressure (though still in normal range)
• More frequent asymptomatic target organ damage such as left ventricular hypertrophy
• Increased metabolic risk factors
• Higher long-term risk of developing diabetes and sustained hypertension

The conversion rate to sustained hypertension is 1-5% per year, with higher rates in those with elevated BP, older age, obesity, or Black race. 1

Management Algorithm

For Confirmed White Coat Hypertension WITHOUT High Cardiovascular Risk:

Do not initiate antihypertensive drug therapy. 1, 2 Instead:

• Implement lifestyle modifications: DASH diet, sodium restriction, weight loss if overweight, regular aerobic exercise 2
• Monitor with ABPM or home BP every 3-6 months to detect transition to sustained hypertension 1, 2
• Reassess diagnosis within 3-6 months 1

For White Coat Hypertension WITH High Cardiovascular Risk or Target Organ Damage:

Consider initiating pharmacological treatment despite normal out-of-office readings. 2 This includes patients with:

• Preexisting cardiovascular disease
• Diabetes mellitus
• Chronic kidney disease
• Evidence of target organ damage (left ventricular hypertrophy, microalbuminuria)

Critical Pitfalls to Avoid

Never rely solely on office blood pressure for diagnosis or treatment decisions—this leads to both overtreatment of white coat hypertension and dangerous undertreatment of masked hypertension. 2, 3

Distinguishing White Coat Hypertension from Masked Hypertension

Masked hypertension is the opposite condition: normal office BP but elevated out-of-office readings—and it carries cardiovascular risk equivalent to sustained hypertension, requiring immediate treatment. 1, 3, 4 Masked hypertension affects approximately 13% of the population and is twice as deadly as true normotension. 1, 3

Screen for masked hypertension in patients with: 1

• Office BP consistently 120-129/75-79 mmHg
• Controlled office BP on treatment but evidence of target organ damage
• High overall cardiovascular risk despite "normal" office readings

White Coat Effect in Treated Patients

In patients already on antihypertensive therapy, the "white coat effect" refers to office BP readings >20/10 mmHg higher than home or ambulatory readings. 1 This can lead to inappropriate treatment intensification and iatrogenic hypotension. 2 Confirm with ABPM before escalating therapy. 1

Proper Home Blood Pressure Monitoring Technique

When using home monitoring to confirm white coat hypertension: 2

• Use a validated automated upper-arm cuff device with appropriate cuff size
• Measure BP morning (before medications) and evening (before dinner)
• Take 2 readings each time, 1 minute apart
• Monitor for 7 consecutive days (minimum 3-4 days)
• Discard all readings from the first day
• Patient should be seated with back and arm supported, feet flat, after 5 minutes of quiet rest
• Calculate average of all remaining readings (minimum 12 readings total)

Ensure at least 70% successful ABPM readings for valid interpretation. 2