Secondary Hypertension

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 exclude possible secondary causes. It is also important to review the patient’s diet and medications. Excessive consumption of sodium, licorice, and alcohol is known to increase the BP. Many drugs such as estrogen (e.g., oral contraceptives), herbals (e.g., ephedra, ginseng, and ma huang), illicit (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) also affect BP.

Table 1. Common Age-based Identifiable Causes of Hypertension.

Age Group% of Hypertension with an Identifiable CauseCommon Etiology
Birth to 12 years70 to 85%Coarctation of the aorta
Renal parenchymal disease
13 to 18 years10 to 15%Coarctation of the aorta
Renal parenchymal disease
19 to 39 years5%Fibromuscular dysplasia
Renal parenchymal disease
Thyroid dysfunction
40 to 64 years8 to 12%Aldosteronism
Cushing syndrome
Sleep apnea
Thyroid dysfunction
≥65 years17%Atherosclerotic renal artery stenosis
Renal failure

In the United States, more than 68 million people, i.e., one in three adults, has HTN.14 Only 30% of adults with HTN are aware of their affliction. Only about 60% of those diagnosed with HTN are receiving antihypertensive therapy and only 50% of those have a BP of <140/90 mmHg.12,14 It is estimated that 70% of the patients with HTN have systolic blood pressure (SBP) between 140 to 159 mmHg and diastolic blood pressure (DBP) between 90 to 99 mmHg. Furthermore, almost 30% (≈65 million) of American adults have prehypertension, i.e., SBP between 120 to 139 mmHg and DBP between 80 to 89 mmHg.15 Prehypertension increases the risk that an individual will go on to develop HTN.