La diagnostica di laboratorio nella sindrome da apparente eccesso di mineralcorticoidi [The laboratory diagnosis of apparent mineralocorticoid excess (AME)]

The apparent mineralocorticoid excess(AME) is a rare genetic disorder caused by impaired activity of the enzyme 11β-hydroxysteroid dehydrogenase type2 (11βHSD2). This abnormality is associated with cortisol excess and abnormal activation of mineralocorticoidreceptor, which is usually only activated by aldosterone. More than 50 known mutations have been associated withAME; whilst some epigenetic modifications may also be involved. AME causes severe hypertension and is hencetraditionally diagnosed during the first years of life. Deficit of 11βHSD2 also occur in other physiopathologicalconditions like pre-eclampsia, sodium-sensitive hypertension and kidney or hepatic impairment. The biochemicaldiagnosis is conventionally made by quantifying tetrahydroxylated metabolites of cortisol (THF and allo-THF) andcortisone (THE) expressed as THF+allo-THF/THE ratio and using home-made Gas Chromatography-MassSpectrometry methods. Nevertheless, some recent studies showed more accurate characterization of 11βHSD2deficit by measuring the urinary free cortisol/cortisone ratio with Liquid Chromatography-Tandem Mass Spectrometry.A final consensus on the preferred method to diagnose AME has not been reached so far, and more studies areneeded for better defining sensitivity and specificity of these tests in some different physiopathological conditionsassociated with 11βHSD2 impairment.