Endocrine Abstracts

Serum 18 hydroxycortisol identifies aldosteronoma in the differential diagnosis of primary aldosteronism

Sowmya Narasimhan^1,2, Alan McGregor^1,2, John Miell^1,2, Susan Mary Chambers^1,2, Hagosa Demoz Abraha (Daines)^1,2 & Simon Aylwin^1,2

¹King’s College Hospital, London, UK; ²University Hospital Lewisham, London, UK.

Introduction: 18-hydroxycortisol (18-OHF) is known to be elevated in glucocorticoid remediable aldosteronism but there are few data relating to 18-OHF in the differential diagnosis of primary aldosteronism.

Aim: We evaluated the usefulness of lying and standing 18-OHF in patients with primary aldosteronism in differentiating between aldosteronoma, bilateral adrenal hyperplasia (BAH) and normality.

Methods: Patients (n=27) with an elevated aldosterone renin ratio (ARR) were further evaluated by assessing lying and standing aldosterone, renin, cortisol and 18-OHF after salt loading. 18-OHF levels (in house flouro-immuno assay, Delfia method) were compared according to adenoma (histological confirmation), BAH (no lesion on imaging with consistent biochemistry) and normality (normalisation of ARR after salt loading).

Results: All data given as mean (range).

Recumbent 18-OHF levels were greater in adenomas than patients with hyperplasia (P≤0.001) and patients with normal ARR (P−<0.01) This was even more clear cut with standing 18-OHF where there was no overlap between adenoma and BAH (P≤0.001).

Conclusion: Although a sub centimetre angiotensin 2 sensitive adenoma might be classified as BAH in our data, 18-OHF is a potentially valuable tool in discriminating adenoma from hyperplasia.

Endocrine Abstracts (2008) 15 OC20