Endocrine Abstracts

A 33 year old male was referred with poorly controlled hypertension. He gave no other past medical or family history. Despite therapy with multiple agents blood pressure was poorly controlled at 200/130 mm/Hg. Initial investigations which included renal ultrasound, magnetic resonance angiography and urine catecholamine excretion were all negative. Plasma renin concentration was suppressed (1 mu/ml/L, normal range 5 to 50) and plasma aldosterone was raised at 650 pmol/L (normal range 200 to 400). Urine tetrahydroaldosterone was also raised (326 micrograms/24 hours (normal range 10 to 120). Adrenal CT scan was normal. However, a subsequent urinary steroid metabolite profile revealed a pattern consistent with late onset 11-beta hydroxylase deficiency, with significant elevation of tetrahydrodeoxycorticosterone (THDOC; 761 micrograms/24 hours, normal range 2 to 28) and tetrahydrodeoxycortisol (THS; 2101 micrograms/24 hours, normal range 3 to 130). Dexamethasone administration suppressed THDOC, THS and THaldo. Screening for glucocorticoid remediable aldosteronism by a conventional long PCR reaction was negative. At present sequencing of CYP11B1, the gene encoding 11-beta hydroxylase, is underway.

This patient has a biochemical pattern on urine steroid metabolite excretion of late onset (non-classical) congenital adrenal hyperplasia due to 11-beta hydroxylase deficiency. This is a rare disorder, with very few cases described in the literature. Contrast to severe 11-beta hydroxylase deficiency (where excess DOC is associated with suppression of renin and aldosterone levels), in this case aldosterone levels in urine and plasma were inappropriately high. We suggest that the relatively modest DOC excess is insufficient to suppress fully angiotensin II and that the chronic ACTH stimulation to the adrenal that is present in the circumstance is associated with increased aldosterone sensitivity to angiotensin II. This may account for some of the other cases that have been described in the literature of aldosterone excess that is suppressible by glucocorticoids in patients who do not have evidence of the classic genetic crossover between CYP11B1 and CYP11B2 that is the usual cause of GRA.