Post-Saline Infusion Plasma Aldosterone Concentrations are Well Correlated with the Lateralized Ratio of Adrenal Venous Sampling in Patients of Primary Aldosteronism

Objective: Adrenal venous sampling (AVS) is the most reliable test to distinguish between unilateral and bilateral primary aldosteronism (PA). However, AVS is invasive, risky, and expensive, and alternative diagnostic methods are desirable. This study aimed to investigate the diagnostic power of saline infusion test (SIT) to distinguish between unilateral and bilateral PA. Design: Retrospective database analysis. Subjects and Methods: We selected 111 patients with PA diagnosed by confirmatory tests who underwent both SIT and successful AVS. Thirty-two patients had lateralized ratio (LR) over 4.0 and 79 patients had LR less than 4.0. Multiple regression analysis and receiver operating characteristic (ROC) analysis were used to examine whether the SIT had good diagnostic power to distinguish between patients with high LR and those with low LR. Results: The patients with high LR had significantly lower serum potassium levels (P<0.0001, Mann-Whitney’s U Test) and higher plasma aldosterone concentrations after SIT (Post-PAC) (P<0.0001). It was revealed that Post-PAC levels were independently associated with the LR by multiple regression analysis (P=0.0112). ROC analysis revealed that the diagnostic accuracy of SIT was very high for distinguishing between patients with high LR and those with low LR. The optimal cut-off value of Post-PAC for the diagnosis of patients with low LR was less than 9.3 ng/dl. Conclusions: SIT is useful for distinguishing between patients with high LR and low LR. It might be possible to omit AVS in patients with a Post-PAC value less than 9.3 ng/dl.Combining the results of serum potassium levels and imaging examinations with SIT might be a potential strategy for PA subtypes.