[Diagnostic problems of Conn's adenomas]

Routine hormone assays and imaging techniques allow a precise positive diagnosis of primary hyperaldosteronism. The main diagnostic problem is to scrupulously apply the test protocol requiring a natriuresis > 100 mmol/24 h and several days of anti hypertensive treatment withdrawal. It is however quite difficult to determine when the diagnosis should be entertained in a hypertensive patient. Potassium level 3/4 3.5 mmol/l is a good sign although normokaliemic primary hyperaldosteronism is well known. Some authors rightly suggest that while potassium level is the best first-line screening test, the aldosterone/renin ratio should nevertheless be measured in all hypertensive patients with a natriuresis above 100 mmol/24 h and potassium 3/4 3.9 mmol/l. Pseudohypermineralocorticism due to excess of a mineralotropic substance other than aldosterone is another interesting though uncommon group of syndromes (congenital blockage of 11-beta-hydroxylase or 17-alpha-hydroxylase). Once the diagnosis has been established, the question of etiology is essential since surgery is indicated in Conn's adenoma and medical treatment in hyperplasia. Although hormone tests are contributive, imaging results are fundamental. In this issue of La Presse Médicale, Leprat et al. report their experience with CT-scan and radiocholesterol scintigraphy with dexamethasone stimulation. In general agreement with others, they have found that these two methods provide generally equivalent sensitivities, but are highly complementary, particularly in the most difficult cases.