The Effectiveness of Metanephrine-Based Compared with Cortisol-Based Measurements to Assess Selectivity and Lateralization of Adrenal Vein Sampling in Primary Aldosteronism: A Systematic Review

PURPOSE: To evaluate the effectiveness of metanephrine-based compared with cortisol-based measurements in assessing successful adrenal vein (AV) cannulation to determine diagnostic AV sampling (AVS) procedures. MATERIALS AND METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, a literature search was conducted using 3 electronic medical databases-PubMed, Embase, and MEDLINE-from inception to the third week of December 2024. Studies that compared metanephrine-based with cortisol-based measurements in adult patients with biochemically established primary aldosteronism undergoing AVS were included. The Methodological Index for Non-Randomized Studies appraisal tool was used for quality assessment. Cohen κ statistic, proportion differences, 95% confidence intervals (CIs), and 2-tailed P values using Z-test for paired proportions were calculated, where applicable. RESULTS: Six studies evaluating a total of 531 patients were included. Metanephrine-based selectivity index (SI) demonstrated significantly higher successful cannulation rates than cortisol-based SI in unstimulated AVS procedures for almost all the comparisons (P < .05), whereas no significant difference was found in stimulated procedures (P > .05). There was excellent agreement between metanephrine-based and cortisol-based SI (κ = 0.876; 95% CI, 0.779-0.972; n = 117) and substantial agreement for lateralization index (LI) (κ = 0.773; 95% CI, 0.658-0.889; n = 115). In patients successfully treated with adrenalectomy, no significant difference was found between metanephrine-based and cortisol-based LIs in identifying dominant side (n = 28). CONCLUSIONS: This study was limited by the quality of evidence and heterogeneity. Compared with cortisol-based SI, metanephrine-based SI significantly increased the proportion of diagnostic unstimulated AVS procedures, supporting the use of metanephrine-based measurements as a reliable alternative.