Van gen naar ziekte; 'apparent mineralocorticoid excess'-syndroom, een syndroom met ogenschijnlijke overmaat aan mineralocorticoïden

Apparent mineralocorticoid excess (AME) is an autosomal recessive disease caused by deficiency of the enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2). 11β-HSD2 converts cortisol into inactive cortisone and prevents the stimulation of the mineralocorticoid receptor by cortisol. In patients with AME, an enhanced stimulation of mineralocorticoid receptors by cortisol in the distal nephron causes an elevated sodium reabsorption and increased potassium excretion. Sodium retention leads to severe low renin hypertension. The diagnosis of AME is based on the detection of an increased concentration of cortisol metabolites and a low or undetectable concentration of cortisone metabolites in urine. Molecular analysis of the HSD11B2 gene confirms the diagnosis. AME is successfully treated by potassium-sparing diuretics, sometimes in combination with loop diuretics (furosemide). Mild forms of AME might occur more frequently than is currently known and should be suspected in patients with hypertension, hypokalemia and decreased plasma renin concentration. Since liquorice can induce the clinical symptoms of AME due to reversible inhibition of the 11β-HSD2 enzyme by glycyrrhetinic acid, the active ingredient of liquorice, patients suspected of having AME should not consume liquorice.