White Coat Hypertension

White coat hypertension is an office blood pressure of 140/90 mm Hg or more with normal out-of-office pressure in an untreated person. Ambulatory 24-hour mean is under 130/80 mm Hg, daytime mean under 135/85 mm Hg, and home mean under 135/85 mm Hg.

The white coat effect is the same gap in a treated patient, in whom clinic readings overstate control and risk overtreatment.

It affects about 15 to 30% of people with office hypertension. It is more frequent in older adults, women, non-smokers, those with grade 1 hypertension, and pregnancy.

About 1 in 5 to 1 in 3 progress to sustained hypertension over 5 to 10 years. Cardiovascular risk is modestly higher than in normotensive people and is greater with diabetes, kidney disease or organ damage.

Pathophysiology. An alerting reaction with sympathetic activation raises pressure in the clinic. Mild metabolic abnormalities and arterial stiffening are more common than in normotensive people.

• Asymptomatic, with anxiety in the clinic and normal home pressures.
• Examination normal, and no target organ damage in most.
• Larger gap between clinic and home readings in older adults and in those with low body mass.

• Repeat office measurement on at least 2 visits with a validated device, correct cuff, rested patient, and unobserved automated readings where available.
• Ambulatory monitoring (preferred): 24-hour mean under 130/80 mm Hg, daytime under 135/85 mm Hg, night time under 120/70 mm Hg. Home monitoring: 7 days, two readings morning and evening, day 1 discarded, mean under 135/85 mm Hg.
• Risk assessment. Creatinine, eGFR, urine albumin to creatinine ratio, glucose, lipids, ECG, fundoscopy, echocardiography when organ damage is suspected.
• Exclude secondary and paroxysmal causes when readings fluctuate widely: sleep apnoea, phaeochromocytoma, thyroid disease.

Differential diagnosis.

• Sustained hypertension
• Masked hypertension (normal clinic, raised out-of-office pressure)
• Anxiety, pain, caffeine and stimulant effects
• Wrong cuff size and measurement error
• Pseudohypertension
• Paroxysmal hypertension from phaeochromocytoma
• Sleep apnoea
• Gestational and pre-eclamptic hypertension in pregnancy

• No routine drug treatment when out-of-office pressure is normal and there is no organ damage or very high cardiovascular risk. Drug therapy is considered with organ damage, diabetes, chronic kidney disease or established cardiovascular disease.
• Lifestyle. Sodium under 2 g daily (salt under 5 g), weight loss, exercise 150 minutes weekly, limited alcohol, and no smoking.
• If a drug is chosen: amlodipine 5 mg orally once daily, increased to 10 mg (maximum 10 mg daily; start 2.5 mg in older adults and liver impairment), or ramipril 2.5 mg orally once daily, increased every 2 to 4 weeks to 10 mg once daily (maximum 10 mg daily, and 5 mg daily at creatinine clearance under 30 mL/min), with potassium and creatinine 1 to 2 weeks after each change. Titrate to out-of-office pressure.
• Treated patients with a white coat effect. Base all changes on ambulatory or home readings to avoid overtreatment, hypotension and falls.
• Cardiovascular risk. Statin by risk (atorvastatin 20 to 40 mg orally once daily, with liver enzymes at baseline and 3 months). Aspirin only for established vascular disease.
• Do not use sedatives or beta blockers to blunt the clinic response.

Special groups.

• Pregnancy: white coat hypertension carries a raised risk of progression to sustained hypertension or pre-eclampsia, so confirm with home or ambulatory readings and review every 2 to 4 weeks.
• Children and adolescents: use age, sex and height percentiles with ambulatory monitoring.
• Region: where ambulatory monitoring is unavailable, use a validated home device with a diary, or serial unobserved office readings by a nurse in a quiet room.

Monitoring. Ambulatory or home monitoring at 3 to 6 months, then yearly. Glucose, lipids, creatinine and urine albumin to creatinine ratio yearly. Repeat sooner with new symptoms, organ damage or weight gain.

Referral and escalation. Refer to a hypertension clinic for organ damage, high risk patients, pregnancy or unclear results. Urgent for office pressure of 180/110 mm Hg or more with symptoms.