Secondary hypertension accounts for about 5–10% of all cases of hypertension with most hypertension being attributed to essential hypertension. It is important to identify patients early with secondary hypertension as timely diagnosis of secondary hypertension can result in potential cure or significant improvement in hypertension with improved quality of life and lower cardiovascular morbidity. Secondary hypertension should be suspected in the following patients (Table 41–1): initial presentation of hypertension at the extremes of age (<30 or >70 years of age), spontaneous hypokalemia, drug resistant hypertension (use of at least three medications at maximal tolerated dose with at least one medication being a diuretic), negative family history of hypertension, recent exacerbation of hypertension that has previously been well controlled, labile hypertension, symptoms of palpitations, sweating and headaches and differential BP in arms and legs. Patients with an identifiable secondary cause of hypertension typically present with a relatively abrupt onset of symptoms (BP ≥160/100 mm Hg) and with considerable target-organ damage (TOD). They typically do not respond as well to lowering BP and to antihypertensive drug therapy as do patients with primary hypertension. The BP-lowering response to specific antihypertensive drugs may offer important clues to the presence and type of secondary hypertension; for example, patients with early renovascular hypertension (RVHT) often have an impressive BP-lowering response to an angiotensin-converting enzyme (ACE) inhibitor or angiotension receptor blocker (ARB) and those with bilateral adrenal hyperplasia as a cause of primary aldosteronism respond well to spironolactone, but not vice versa. The initial evaluation for secondary hypertension is shown in Table 41–2 and will be discussed in detail in the chapter. The choice of tests and the order in which they are obtained depend not only on the pretest probability of the disease, but also on safety, availability, local expertise with the test, and its cost.
Table 41–1.Who to work up for secondary hypertension. |Favorite Table|Download (.pdf) Table 41–1. Who to work up for secondary hypertension.
|New onset hypertension at young age (<30 years old; >70 years old) |
|Negative family history of hypertension |
|Acute exacerbation of previously well controlled hypertension |
|Resistant hypertension (three drugs prescribed at optimal doses with one drug being a diuretic) |
|Spontaneous hypokalemia |
|Headaches, sweating, and palpitations |
|Epigastric bruit |
|Differential BP in arms and legs |
|Hypertension and an adrenal mass |
Table 41–2.Initial evaluation for secondary hypertension. |Favorite Table|Download (.pdf) Table 41–2. Initial evaluation for secondary hypertension.
|Plasma renin and serum aldosterone levels |
|Plasma or urine metanephrine levels |
|Sleep study |
|Renal Doppler |
|CT angiogram/MR angiogram |
|24 urine cortisol (if indicated) |
Recognition of important clinical clues for RVHT is paramount in the clinical diagnosis of this condition. RVHT probably occurs in less than 1% of unscreened patients with mild hypertension; however, ...