Mr. U is a 48-year-old man with a BP of 165/90 mm Hg.
|What is the differential diagnosis of hypertension? How would you frame the differential?|
First, what is normal BP, and when is a patient hypertensive? The first step is accurately measuring the BP. Table 20–1 summarizes guidelines for obtaining valid BP measurements.
Table 20–1. Guidelines for Measuring BP. |Favorite Table|Download (.pdf)
Table 20–1. Guidelines for Measuring BP.
- The patient should sit for several minutes in a quiet room before BP measurements are taken. Pain, stress, a full urinary bladder, a recent meal, and talking or active listening during measurement affect BP. Having smoked a cigarette within 15–20 minutes can elevate the BP by 5–20 mm Hg.
- Take at least 2 measurements spaced by 1–2 minutes and additional measurements if the first 2 are quite different.
- Using a bladder that is too narrow yields false high readings. Instead of the standard cuff (12–13 cm long, 35 cm wide) use an appropriate larger cuff in patients with increased arm circumference.
- Use phase I (first tapping sound) and V (disappearance) Korotkoff sounds to identify systolic and diastolic BP values, respectively.
- Do not deflate the cuff too rapidly, otherwise individual Korotkoff sounds are missed and too low a value is measured; start with a deflation rate of 2 mm/s.
- Measure the heart rate by palpation and watch out for arrhythmia, which mandates repeated BP measurements.
- At the first visit, measure BP in both arms and take the higher value as the reference; measure BP at 1 minute and 5 minutes after standing upright if the patient has a disorder that frequently causes orthostatic hypotension.
The most recent Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High BP (JNC 7) classifies BP as follows, based on the mean of 2 seated BP measurements on each of 2 or more office visits:
Normal: systolic BP < 120 mm Hg and diastolic BP < 80 mm Hg.
Prehypertension: systolic BP 120–139 mm Hg or diastolic BP 80–89 mm Hg.
Stage 1 hypertension: systolic BP 140–159 mm Hg or diastolic BP 90–99 mm Hg.
Stage 2 hypertension: systolic BP ≥ 160 mm Hg or diastolic BP ≥ 100 mm Hg.
Hypertension is either primary (essential) or secondary (resulting from a specific identifiable cause). Causes of secondary hypertension can be organized using an organ/system framework:
Primary (essential) hypertension
Chronic kidney disease
Acute renal failure
Coarctation of the aorta
Pulmonary: sleep apnea
Drug-induced or drug-related
Prolonged corticosteroid therapy
Nonselective nonsteroidal antiinflammatory drugs (NSAIDs)
Cyclooxygenase (COX)-2 inhibitors
Sympathomimetics (decongestants, anorectics)
Cyclosporine and tacrolimus
Stimulants (modafinil, amphetamines)