Endocrine Abstracts

Background: 131I-norcholesterol scintigraphy (INCS) is currently not considered a main confirmatory and localizing study in primary aldosteronism (PA), however few recent data is available. On the other hand, adrenal venous sampling (AVS) is technically difficult, and may also lead to erroneuos diagnosis.

Aim: To describe the performance of INCS, done under dexamethasone (DXM) supression, in daily practice.

Patients and methods: Retrospective study of the 36 INCS-DXM performed from 1/2011 to 12/2017 at our centre, that were requested in cases of PA to decide surgery. DXM 4 mg/day was administered from day -7 to the fourth day of detection. Images were adquired at 24, 48 h, and late images, off of DXM, on 5th/7th day.

Results: 20 (55.56%) were male, mean age was 58.6±13.7 years. INCS was negative in 22 patients (61,1%), 11 cases (30.5%) showed unilateral autonomous nodular uptake (UANU). In three cases the report was glandular assymetry (2) or bilateral hyperplastic behaviour (1), and were treated conservatively. After committee decision nine patients (25%) were operated on (laparoscopic adrenalectomy). Eight of them had congruent UANU with ipsilateral adenoma by CT, and blood preassure ressolved completely (7) or improved (1). Only one patient with negative INCS was adrenalectomized and cured of Conn’s adenoma, standing for the only false negative result (11%). 3 cases with UANU were not operated on (one had serious comorbidities, one showed contralateral adenoma on CT but refused AVS, one mild case preferred medical treatment). The sensitivity of INCS among surgical confirmed cases was 88.8%. In this series, INCS-UANU was associated to adrenalectomy (P 0.01). Hypokaliemia was associated to INCS positivity (P<0.016) and to surgery (P<0.001). Supressed renin (<0.5 ng/ml/h) did correlate to INCS positivity (P 0.001) and adrenalectomy (P 0.045), however neither plasmatic aldosterone nor aldosterone/renin ratio >30 did. Adenoma’s mean size was not related to INCS result (P 0.7) or to surgical management (1.74±1.2 vs 1.72±0.45 mm) (P 0.9). Neither the INCS result nor the treatment were associated to gender, however, the mean age of the operated was significantly younger (47.4±15.1 vs 62.2±11.6) (P 0.022).

Conclusions: The usefulness of INCS in the work up of primary hyperaldosteronism due to Conn’s adenoma is confirmed, with a sensitivity of 88%. INCS is a minimally-invasive functional imaging that should be taken into account before performing AVS.