Dexamethasone-suppressible hyperaldosteronism: studies on overproduction of 18-hydroxycortisol in three affected family members.
We report a newly diagnosed family in which a father and his two sons were found to be hypertensive and to have the rare familial condition dexamethasone-suppressible hyperaldosteronism (DSH). All three patients became normotensive on dexamethasone treatment alone and have been successfully maintained on low doses of the drug for 6 months since diagnosis. Each of the patients had extremely high plasma and urinary concentrations of the recently discovered steroid 18-hydroxycortisol, which were more than ten times higher than the upper normal limit. Plasma levels were readily suppressed by dexamethasone treatment. The hypothesis that 18-hydroxycortisol might derive from 18-hydroxylation of recirculating cortisol was tested by measuring plasma 18-hydroxycortisol levels during low-dose and high-dose hydrocortisone infusions, in a normal subject and in one of the patients with DSH. During the high-dose infusions (with plasma cortisol levels of 3000-5000 nmol/l) there was net production of 18-hydroxycortisol within 8 h, but this was not observed during the low-dose infusions (plasma cortisol levels 300-400 nmol/l). The origin of 18-hydroxycortisol remains uncertain: these findings do not support the recirculation theory, but lend weight to the alternative hypothesis that 18-hydroxycortisol is produced in transitional adrenocortical tissue. This steroid is of considerable value in the differential diagnosis of primary hyperaldosteronism and may also be important as a marker of transitional adrenal cell function.