Adrenocortical causes of
hypertension are established by examining the
mineralocorticoid hormones produced in the zona glomerulosa and zona fasciculata. In the zona glomerulosa,
aldosterone excess leads to
hypertension,
hypokalemia, and suppressed plasma
renin activity, with increased concentrations of urinary
aldosterone (either as the 18-
glucuronide or free
aldosterone) as an index of its production. Identifying a
tumor by computed tomography scan verifies the diagnosis of a correctable lesion. If no
tumor is found, several maneuvers are used to identify primary adrenal
hyperplasia, a disorder with autonomous
aldosterone production, for which reduction of adrenal mass is curative. The zona fasciculata has two major pathways: the 17-deoxy pathway, where
deoxycorticosterone (DOC) and
corticosterone are the significant
steroids, and the 17-hydroxy pathway, which leads to
cortisol production.
Tumors of the 17-deoxy pathway, DOC-producing
adenomas, have increased concentrations of DOC and its precursor
steroids, normal concentrations of
cortisol, and suppression of
aldosterone production secondary to suppression of the
renin system. Two enzymatic defects in the zona fasciculata, 11 beta- and
17 alpha-hydroxylase deficiency, can be first readily identified by the
virilization in the former, hypogonadal features in the latter.
Steroid patterns are diagnostic. DOC is produced in excess in both deficiencies and is the cause of the
hypertension. Deficient or impaired 11 beta-hydroxy
steroid dehydrogenase in the
apparent mineralocorticoid excess syndrome or after licorice ingestion retards the conversion of
cortisol to inactive
cortisone in the kidney, leading to
mineralocorticoid hypertension; this leads to suppression of the
renin system and subsequently of
aldosterone.