The association between systolic blood pressure reduction during clonidine suppression testing and the decrease in plasma catecholamines and metanephrines

Golani, Tiran; Fishman, Boris; Sharabi, Yehonatan; Olswang-Kutz, Yael; Leibowitz, Avshalom; Grossman, Ehud; Shlomai, Gadi

doi:10.1530/endoabs.70.aep1008

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“…The reported effects of clonidine on BP and heart rate were comparable to those reported previously. 29 That study outlined a correlation of BP decrease at 90 minutes after clonidine, with relative NMN decrease in 36 patients in whom PPGL was excluded by CST. Accordingly, a BP decrease at 90 minutes after clonidine was suggested as an immediate clinical indicator in the diagnosis of PPGL.…”

Section: Discussionmentioning

confidence: 99%

Improved Diagnostic Accuracy of Clonidine Suppression Testing Using an Age-Related Cutoff for Plasma Normetanephrine

Remde

Pamporaki

Quinkler³

et al. 2022

Hypertension

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Background: Moderately elevated plasma normetanephrine (NMN) levels are frequent among patients with suspected pheochromocytoma and paraganglioma (PPGL). Clonidine suppression testing (CST) is recommended to distinguish patients with from those without PPGL. We aimed at evaluating the diagnostic outcome of CST in patients with moderate NMN elevations. Methods: Data from patients participating in the PMT study (Prospective Monoamine-Producing Tumor) and the ENSAT (European Network for the Study of Adrenal Tumours) registry in 6 European reference centers were analyzed retrospectively. Eighty-nine patients with suspected PPGL and moderate NMN elevations upon screening were included. During follow-up, PPGL was confirmed in 16 and excluded in 73 cases. Plasma NMN was measured by liquid chromatography tandem mass spectrometry before and 180 minutes after oral clonidine. Receiver operating characteristic analysis was performed to identify optimal cutoffs. Results: If published diagnostic criteria for CST (ie, NMN ≥112 ng/L and NMN suppression <40%) were applied, a sensitivity of 88% (CI, 61%–98%) and a specificity of 97% (CI, 90%–100%) were observed. An improved cutoff for plasma NMN 180 minutes after clonidine was established at 80% of the age-related upper limit of normal, resulting in a sensitivity of 94% and a specificity of 97%. False-negative CST results occurred in 2 patients with small PPGL. Conclusions: This study, involving one of the largest cohorts of patients with suspected PPGL and moderately elevated NMN, confirmed the diagnostic accuracy of CST. The application of an adapted cutoff further improved sensitivity.

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Section: Discussionmentioning

confidence: 99%