[Adrenal cortex scintigraphy with and without dexamethasone suppression in the study of primary aldosteronism]

To evaluate the diagnostic performance and efficacy of adrenal scintigraphy in primary aldosteronism following the protocol that combines adrenal suppression scintigraphy plus non-suppression study.

20 patients referred to our service with the suspicion of primary aldosteronism were studied by combined scintigraphy. Thirteen men and 7 women, mean age of 52 years, aged from 31 to 73 years, were included. Uptake of free iodine by the thyroid was inhibited by oral Lugol 5 % administration. Dexamethasone 4 mg per day was administered from day 7 to the third day of detection, when administration was stopped. Adrenal scintigraphy was performed after intravenous injection of I-131-norcolesterol (37 MBq). Images were taken at 24 and/or 48 hours and on the third day. Afterwards, dexamethasone administration was stopped and late images on 5th and/or 7th days were obtained. The scintigraphic result was confirmed with the final clinical evaluation (FCE) of the patient.

11 patients presented pathological studies, 9 adenomas (8TP + 1FP) and 2 bilateral adrenal hyperplasia (2TP); 7 normal scintigraphies (6TN and 1 non-conclusive FCE) and 2 non-conclusive scintigraphies (1 incidentaloma and 1 non-conclusive FCE). Normal adrenal glands were visualized in all cases on the 5th and/or 7th day scintigraphy.

The study of adrenal functionalism by the combined protocol of adrenal suppression study plus later non-suppression study made it possible to identify with high precision primary aldosteronism and to confirm the function of normal adrenal glands.