PSUN25 Adrenal Incidentaloma: Is Interval Hormone Testing Warranted?

BACKGROUND: The prevalence of adrenal incidentaloma (AI) is increasing, with pressure on healthcare systems. While earlier guidelines recommended repeat endocrine testing to ensure stability, the recent European guidelines suggest that is not necessary if initial tests were reassuring. AIM: To explore the utility of this guidance on repeat endocrine testing of AI. METHODS: Retrospective unselected review of AI cases reviewed before the European guidelines, based on local protocol (baseline overnight dexaethasone suppression test [ONDST] and plasma metanephrines +/- aldosterone: renin ratio [ARR] if hypertension or hypokalemia were present). At two years, the endocrine tests were repeated. We compared the baseline with the two-year follow-up data. RESULTS: We collected data on 54 patients initially identified (2011-2016). Post-ONDST cortisol (nmol/L): At baseline, 37/52 (71.1%), 12/52 (23.1%) and 3/52 (5.8%) had values <50, 51-138 and >138 respectively. After 2 years, 20/28 (71.4%) had results of <50, of which 18 were originally <50 and 2 were 51-138. The remaining 8 had values of 51-138, of which 6 had values of <50 at baseline and the other 2 had values of 51-138. Where there appeared some discordance, analysis of agreement (kappa statistics) showed an agreement of 71% (P=0.153). Wilcoxon signed-rank test to explore changes in the raw cortisol values showed that there was no significant difference (P=0.281). ARR: Data was available data on 40 patients, all of whom had normal ARR results. At 2 years there were data on 25 cases, 19 of which also had baseline values, while 6 had 2-year values but no baseline data. In all cases, 2-year ARR values were normal. Plasma metanephrines: Metanephrine: Data was available at baseline on 43 patients, with 8 (18.6%) having values above the reference range (>0.33 nmol/L). Of these 8, 7 had values between 0.33 and 0.46, with the remaining one having a single markedly raised value at 206.8 nmol/L. At 2 years, we had data on 23 of these 43 patients, out of whom 20 had normal levels at both baseline and 2 years, 2 had abnormal results at baseline but normal at 2 years and one normal baseline value but slightly raised (0.36 nmol/L) at two years, with normal normetanephrines (0.33 nmol/L). Normetanephrine: Of the 43 cases with baseline results, only one was abnormal at 802 nmol/L (the same patient with a plasma metanephrine of 206.8 nmol/L). In this case, the normetanephrine became unremarkable after 2 years indicative of successful surgery. The remaining 22 cases with data at 2 years all had values within the reference range. CONCLUSION: There was no significant change in function after two-year follow up, as defined by abnormal endocrine test results. Therefore, our findings support the European guidelines advice that repeat testing is not warranted. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.