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About 5 to 10 percent of patients with high BP have secondary HTN. By definition, secondary HTN has an identifiable and potentially correctable cause (Table 1).13 Whenever a patient is diagnosed with high BP, one purpose of the initial assessment (i.e., history, physical examination, and basic laboratory testing) is to identify possible secondary causes. The dietary habits and medication profile is also assessed. Excessive consumption of sodium, licorice, and alcohol is known to increase the BP. Agents such as estrogen (e.g., oral contraceptives), herbals and supplements (e.g., ephedra, ginseng, and ma huang), illicit drugs (e.g., amphetamines and cocaine), NSAIDs, CNS drugs (e.g., buspirone, carbamazepine, clozapine, fluoxetine, lithium, and tricyclic antidepressants), steroids, and sympathomimetic agents (e.g., decongestants and diet pills) may also affect BP.
| Age Group | % of Hypertension with an Identifiable Cause | Common Etiologies |
|---|---|---|
| Birth to 12 years | 70 to 85% | Coarctation of the aorta Renal parenchymal disease |
| 13 to 18 years | 10 to 15% | Coarctation of the aorta Renal parenchymal disease |
| 19 to 39 years | 5% | Fibromuscular dysplasia Renal parenchymal disease Thyroid dysfunction |
| 40 to 64 years | 8 to 12% | Aldosteronism Cushing syndrome Pheochromocytoma Sleep apnea Thyroid dysfunction |
| ≥65 years | 17% | Atherosclerotic renal artery stenosis Hypothyroidism Renal failure |
The most recent American College of Cardiology/American Heart (ACC/AHA) Association Task Force on Clinical Practice Guidelines for BP management introduced a more conservative threshold for hypertension (Figure 3).14 As a consequence, the number of patients with HTN has increased from 32 percent to 46 percent (68 million to 103 million) of adults 18 years and older in the United States.15 The risk of developing HTN varies by race and increases dramatically with age. For adults 45 years of age without HTN, the 40-year risk of developing HTN was 93% for African-American, 92% for Hispanic, 86% for white, and 84% for Chinese adults.
| SBP | DBP | ||
|---|---|---|---|
| Normal | <120 mm Hg | and | <80 mm Hg |
| Elevated | 120–129 mm Hg | and | <80 mm Hg |
| Hypertension | |||
| Stage 1 | 130–139 mm Hg | or | 80–89 mm Hg |
| Stage 2 | ≥140 mm Hg | or | ≥90 mm Hg |
Only 30% of adults with HTN are aware of their condition and only about 60% of those diagnosed with HTN are receiving antihypertensive therapy.16
