Abstract

Fifty million adults (43%) in the United States have hypertension. The prevalence of secondary hypertension is variably estimated at between 1 and 20% of adult hypertensives, depending on the clinical population assessed. Though relatively rare, the absolute number of persons affected is substantial. The diagnosis of secondary causes is critical, as these forms of hypertension are potentially curable with specific therapies based on underlying etiologies. Common etiologies of secondary hypertension are generally classified according to renal, endocrine or other miscellaneous origins. Renal parenchymal disease is often considered as most prevalent. Primary aldosteronism, parathyroid and thyroid dysfunctions are among endocrine causes. Other important causes include obstructive sleep apnea and medication or other chemical interactions. Obesity has recently been identified as a potential secondary etiology. The actual prevalence of secondary hypertension is not known.

Recognizing the inadequacy of current prevalence data, we analyzed the rates of secondary hypertension among first time patients in a major southeastern hypertension referral clinic for one year. A preliminary evaluation of a random selection of 25% (N=40) of new patients seen between January and June 2000 revealed the following prevalence of secondary hypertension: (See Table)

Secondary EtiologyRate
Renal Parenchymal10%
Endocrine
Aldosteronism7.5%
Thyroid7.5%
Other Miscellaneous
Obstructive Sleep Apnea15%
Dysautonomia2.5%
Medications/chemical12.5%
Obesity60%
Secondary EtiologyRate
Renal Parenchymal10%
Endocrine
Aldosteronism7.5%
Thyroid7.5%
Other Miscellaneous
Obstructive Sleep Apnea15%
Dysautonomia2.5%
Medications/chemical12.5%
Obesity60%
Secondary EtiologyRate
Renal Parenchymal10%
Endocrine
Aldosteronism7.5%
Thyroid7.5%
Other Miscellaneous
Obstructive Sleep Apnea15%
Dysautonomia2.5%
Medications/chemical12.5%
Obesity60%
Secondary EtiologyRate
Renal Parenchymal10%
Endocrine
Aldosteronism7.5%
Thyroid7.5%
Other Miscellaneous
Obstructive Sleep Apnea15%
Dysautonomia2.5%
Medications/chemical12.5%
Obesity60%

While prevalence rates are expected to be higher among referral populations, and may be unique to the particular population studied, an accurate analysis of likely rates of secondary hypertension provides important guidance for clinical evaluation of challenging cases. Implications for primary care and hypertension specialist providers will be addressed.

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