**4.8 Glucocorticoid remediable hypertension**

Glucocorticoid remediable hypertension (also known as familial hyperaldosteronism type I) is characterised by autosomal dominant hypertension, low plasma renin levels, normal plasma aldosterone levels and hypokalemia (McMahon &Dluhy, 2004). The age of onset of hypertension is usually in teenage years, but may be in adulthood. Hypertension is typically refractory to treatment. The molecular basis for disease is secondary to a chimeric gene, involving CYP11B1, encoding 11-beta-hydroxylase and CYP11B2, encoding aldosterone synthase. The chimeric gene results in aldosterone synthesis under the regulatory control of ACTH, resulting in hyperaldosteronism (Lifton, et al., 1992). Thus, the causative mutation affects the cortical collecting duct indirectly, and therefore this is not a "tubulopathy". Traditionally, diagnosis has been made by a dexamathasone suppression test, which results in reduced plasma aldosterone levels. A specific urinary profile of 18 oxotetrahydrocortisol and 18 hydrocortisol may be sought, but molecular genetic testing also allows a definitive diagnosis. Treatment with glucocorticoids (using shorter acting agents prednisone or hydrocortisone) is often effective, but additional antihypertensives may be needed as adjuncts.
