Essential hypertension

What it is

Essential hypertension, or primary hypertension, is about 95% of hypertension cases, and the main causes in such patients are genetic and environmental factors. Secondary hypertension is about 5% of cases, in whom the cause of high BP can be identified and sometimes treated. Hypertension itself is a resting systolic BP of 140 mmHg or more and/or a diastolic BP of 90 mmHg or more. Two classifications are given and they do not agree. JNC 7 reads: normal <120 and <80; prehypertension 120-139 or 80-89; stage 1 HTN 140-159 or 90-99; stage 2 HTN >160 or >100. The national guideline, Management of Hypertension in Primary Health Care, classifies by grade instead:

1. Optimal: systolic under 120 and diastolic under 80
2. Normal: 120-129 and/or 80-84
3. High normal, which the same table also calls prehypertension: 130-139 and/or 85-89. That name belongs to the national table, and it does not match the JNC 7 band above, 120-139 or 80-89
4. Grade 1 hypertension: 140-159 and/or 90-99

Grade 2 hypertension: 160-179 and/or 100-109. Grade 3 hypertension: 180 or more and/or 110 or more. Isolated systolic hypertension: 140 or more with a diastolic under 90. The grade is set by the higher of the two figures, whether systolic or diastolic, and isolated systolic hypertension is itself classified as grade 1, grade 2 or grade 3 according to the systolic value. Four further terms are often confused:

1. White coat hypertension: an office BP usually higher than the BP measured out of the office in untreated people, ascribed to the alerting response, anxiety or a conditional response to the unusual situation; the ABPM day average is normal, <135/85.
2. Masked hypertension: BP that is normal in the office and abnormally high out of the medical environment in untreated people, also termed isolated ambulatory hypertension, and given elsewhere as BP that is consistently elevated by out-of-office measurements but does not meet the criteria for hypertension based on office readings.
3. White-coat uncontrolled hypertension: elevated office readings with controlled home or ambulatory BP in treated people.
4. Masked uncontrolled hypertension: controlled office readings but elevated home or ambulatory BP in treated patients.