1. Secondary hypertension (defined as hypertension due to an identifiable cause) affects only 5-10% of hypertensive patients.
2. The following are characteristics suggestive of secondary hypertension: early onset of hypertension (less than 30 year), resistant hypertension (defined as hypertension despite the use of three antihypertensive drugs including a diuretic at the optimal dosages), severe hypertension (greater than 180/110 mm Hg), sudden increase of blood pressure (BP) in a previously stable patient, non-dipping or reverse dipping during 24-hour ambulatory BP monitoring (ABPM), and presence of target organ damage.
3. Before screening for secondary arterial hypertension, pseudo-hypertension (defined as cuff diastolic BP at least 15 mm Hg higher than simultaneously measured intra-arterial BP) and pseudo-resistance (due to inadequate measurement techniques, as with too small cuff size) need to be excluded.
4. ABPM is the best measurement method to assess arterial BP, and allows for exclusion of white-coat hypertension, assessment of treatment adherence, confirmation of resistant hypertension, and assessment of dipping status.
5. The absence of a night-time drop in BP (“dipping”) of >10% relative to the daytime value during ABPM is associated with several secondary forms of hypertension.
6. Obstructive sleep apnea is one of the most common causes of secondary hypertension. Nocturnal hypoxemia may impact the renin-angiotensin-aldosterone system and increase sympathetic nerve activity.
7. The authors wrote, “Practicing physicians cannot simply ‘forget’ about renal artery stenosis despite the fact that randomized trials show little if any benefit of revascularization.” The authors suggest that urgent revascularization could be “lifesaving” in those with flash pulmonary edema secondary to bilateral renal artery stenosis.
8. There are insufficient data on the long-term effects of renal denervation on arterial BP.
9. Primary aldosteronism may be suggested by hypokalemia (albeit only in 40% of patients), resistant hypertension, muscle weakness, constipation, and fatigue. The plasma aldosterone-renin ratio (ARR) is a screening test for primary aldosteronism. Antihypertensive medication should be changed to those with minimal effects on ARR (e.g., verapamil, hydralazine, or doxazosin) prior to laboratory testing.
10. Even after identification and treatment of a secondary cause of hypertension, BP may not return to normal. This is likely secondary to concomitant essential hypertension and/or vascular remodeling that has occurred over time.
Posted by: Steven Almany M.D.