Which clinical characteristics support the diagnosis of monogenic hypertension?
Monogenic hypertension should be considered in patients below the age of 30 years, who present with severe or refractory hypertension and a family history of early-onset hypertension. In addition, associated biochemical abnormalities should raise suspicion. The presence of hypokalemia associated with metabolic alkalosis is suggestive of excess presence or activation of the mineralocorticoid pathway. Familial or spontaneous severe hypertension associated with hyperkalemia and metabolic acidosis (in setting of normal glomerular filtration rate) can be suggestive of pseudohypoaldosteronism type 2 (PHA 2; formerly known as Gordon syndrome).
A low renin value is shared by most of these disorders. Aldosterone activity may be decreased or increased. A typical example of low renin and aldosterone levels is Liddle syndrome. In contrast, a higher level of aldosterone release is seen in glucocorticoid-remediable aldosteronism (GRA, familial hyperaldosteronism type I). Both familial and sporadic forms of primary hyperaldosteronism exhibit typically a serum aldosterone-renin ratio (ARR) greater than 30 and a serum aldosterone value ≥15 ng/dL. A positive ARR should be confirmed with a 24-hour urine aldosterone measurement of greater than 14 μg in the setting of high salt intake (urine sodium over 200 mEq/day).