Secondary Hypertension

Hypertension affects about 30% of adults in the United States.[1] Most cases are due to essential hypertension, i.e., hypertension without an identifiable cause. But, about 5 to 10% of cases of hypertension are due to secondary hypertension.[2] Secondary hypertension is elevated blood pressure (BP), which is secondary to an identifiable cause. Since its prevalence is relatively low, performing routine evaluations in every case of hypertension is not cost effective and is also time-consuming. However, one must be aware of clinical clues that could suggest a secondary cause of hypertension. The clinical clues to look out for that could be suggestive of a secondary cause of hypertension are as follows[3]: Resistant hypertension, i.e., persistent blood pressure greater than 140/90 mm Hg despite using three anti-hypertensives from different classes, that includes a diuretic, all at adequate doses. Increased lability or acute rise in blood pressure in a patient who had previously stable pressures. Hypertension that develops in non-black patients less than 30 years of age, who do not have any other risk factors for hypertension, e.g., obesity, family history, etc. Patients with severe hypertension (BP greater than 180/110 mm Hg) and patients with end-organ damage like acute kidney injury, neurological manifestations, flash pulmonary edema, hypertensive retinopathy, left ventricular hypertrophy, etc. Hypertension that is associated with electrolyte disorders like hypokalemia or metabolic alkalosis. Age of onset of hypertension before puberty. Non-dipping or reverse dipping presents while monitoring 24-hour ambulatory blood pressure. (Normally, the blood pressure at night is lower than the blood pressure during the day, i.e., there is a ‘dip’ in blood pressure at night. The absence of this ‘dip’ or ‘reverse dipping,’ i.e., ‘dip’ present during the day instead of at night can be suggestive of a secondary cause of hypertension).