Endocrine Abstracts

Background: Adrenal venous sampling (AVS) is the gold standard to differentiate patients with unilateral primary aldosteronism (UPA) from those with bilateral disease (BPA). As this is an invasive method, there are a lot of different scoring systems developed for primary aldosteronism (PA) subtyping. Integer scoring system is one of those established for BPA subtyping.

Objective: The aim of this study was to evaluate the efficiency of using the online Integer scoring system in predicting BPA, as a possible surrogate for AVS.

Methods: We performed a retrospective analysis of 105 patients (66 female, median age at diagnosis 53 years (20-75)) treated for PA in our center between 2015 and 2022. AVS was bilaterally successful in 86 (82%) patients. According to AVS, 52 (60%) patients were diagnosed as UPA and 34 (40%) as BPA. The Integer score was calculated based on serum potassium level (<3.9 mmol/l - four points, 3.5-3.9 mmol/l - three points), sex (female sex - one point), imaging finding on CT (absence of nodules during computed tomography - three points), baseline plasma aldosterone concentration (<210 pg/ml - two points) and baseline aldosterone to renin ratio (<620 - two points). The result above 8 was considered as predictive for BPA.

Results: Of 34 patients diagnosed with BPA using the AVS, the Integer score was diagnostic in 9 of them, giving a positive predictive value of 26%. The negative predictive value was 96%, sensitivity 82% and specificity 67%. The median score for BPA subtyping in our patients was 4 with a range from 3.5 to 6.

Conclusion: Our results suggest that Integer scoring system is not applicable for PA subtype prediction in our center and that each center should determine their own score. To the extent that each center does not have a scoring system, AVS remains the only diagnostic method for subtyping PA.