Circulating soluble CXCR4 fails to differentiate subtypes of primary aldosteronism.

Accurate subtyping of primary aldosteronism (PA) is essential for treatment selection. This study examined whether soluble CXC chemokine receptor type 4 (sCXCR4) in peripheral blood reflects adrenal CXCR4 expression assessed by 68Ga-pentixafor PET/MR, and whether sCXCR4 aids PA classification. A total of 160 subjects were enrolled, including 88 patients with PA (52 aldosterone-producing adenoma [APA], 36 idiopathic hyperaldosteronism [IHA]) and 72 healthy volunteers. Serum sCXCR4 was measured by enzyme-linked immunosorbent assay. Group comparisons, correlation analyses, and receiver operating characteristic curves were used to evaluate diagnostic performance. Serum sCXCR4 did not differ significantly among APA, IHA, and controls, and showed no correlation with adrenal SUV_max on PET/MR. The discriminatory value for distinguishing APA from IHA was poor (AUC 0.52; 95% CI 0.40-0.64). These results suggest that circulating sCXCR4 does not mirror adrenal CXCR4 expression and has no diagnostic role in PA subtyping.