Serum 18-hydroxycortisol in primary aldosteronism, hypertension, and normotensives

This study reports the determination of plasma 18-hydroxycortisol (18-OHF) using a new and easy enzyme-linked immunosorbent assay (ELISA) method in pr imary aldosteronism and compares the values found in essential hypertensive s and normotensive controls. In primary aldosteronism, we evaluated usefuln ess of plasma 18-OHF determination and the dexamethasone suppression test i n the diagnosis of glucocorticoid-remediable aldosteronism using the geneti c test as the gold standard. We studied 31 primary aldosteronism patients, 101 essential hypertensives, and 102 healthy normotensive controls. The pla sma 18-OHF was measured using a biotin-avidin enzyme-linked assay by a new and purified polyclonal antibody. The 18-OHF value in primary aldosteronism was 6.3 +/- 8.05 nmol/L; this value is significantly higher than the value found in essential hypertensives and normotensive controls (2.81 +/- 1.42 and 2.70 +/- 1.41 nmol/L, respectively; P <0.0005). In primary aldosteronis m, 4 of 31 patients had 18-OHF levels that were 10 times higher than the no rmal upper limit (2.983 nmol/L). The dexamethasone suppression test in prim ary aldosteronism patients was positive (serum aldosterone <4 ng/dL) in 13 of 31 cases. A chimeric CYP11B1/CYP11B2 gene was demonstrated in 4 primary aldosteronism patients, corresponding to the same cases that had higher lev el of 18-OHF. In conclusion, plasma 18-OHF determination by this ELISA meth od is reliable for detecting glucocorticoid-remediable aldosteronism, and i t does so better than the dexamethasone suppression test.