A seated saline loading test (SLT) using liquid chromatography-tandem mass spectrometry (LC-MS/MS) is one of the most accepted confirmatory tests of primary aldosteronism. However, LC-MS/MS is time-consuming and is not widely available in diagnostic laboratories compared to immunoassay. With immunoassay, it is unknown whether SLT in the seated position is more accurate than that of the supine position, and a cutoff value of post-seated SLT plasma aldosterone concentration (PAC) must be established in the Korean population. Ninety-eight patients underwent SLT in both positions, and post-SLT PAC was measured by LC-MS/MS and radioimmunoassay. We confirmed primary aldosteronism if post-seated SLT PAC by LC-MS/MS exceeded 5.8 ng/dL. The area under the receiver operating characteristic curve was greater for seated than supine SLT (0.928 vs. 0.834, P=0.003). The optimal cutoff value of post-seated SLT by radioimmunoassay was 6.6 ng/dL (sensitivity 83.3%, specificity 92.2%).
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Investigating the cut-off values of captopril challenge test for primary aldosteronism using the novel chemiluminescent enzyme immunoassay method: a retrospective cohort study Yuta Tezuka, Kei Omata, Yoshikiyo Ono, Kengo Kambara, Hiroki Kamada, Sota Oguro, Yuto Yamazaki, Celso E. Gomez-Sanchez, Akihiro Ito, Hironobu Sasano, Kei Takase, Tetsuhiro Tanaka, Hideki Katagiri, Fumitoshi Satoh Hypertension Research.2024;[Epub] CrossRef
Background Pheochromocytoma and paraganglioma (PPGL) is diagnosed through biochemical confirmation of excessive catecholamines in urine and plasma. Recent technological developments have allowed us to measure urinary free metanephrines; however, the diagnostic accuracy of these new methods and the diagnostic cutoff values have not been evaluated.
Methods This is a retrospective study of 595 subjects, including 71 PPGL cases and 524 controls. PPGL was based on pathological confirmation. Subjects with no evidence of PPGL over 2 years were included in the control group.
Results Urinary free metanephrines yielded similar area under the curve (AUC) to urinary fractionated metanephrines and plasma free metanephrines. However, urinary free normetanephrine yielded a better AUC than did urinary fractionated normetanephrine. The optimal cutoff for urinary free metanephrine and normetanephrine corrected for urinary creatinine yielded 97.2% sensitivity and 98.1% specificity.
Conclusion Urinary free metanephrines are a reliable method for diagnosing PPGL in Asian populations compared with existing biochemical methods.
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Biochemical Assessment of Pheochromocytoma and Paraganglioma Graeme Eisenhofer, Christina Pamporaki, Jacques W M Lenders Endocrine Reviews.2023; 44(5): 862. CrossRef
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