https://orcid.org/0000-0003-4719-065X
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Anna Casteràs, Enzamaria Fidilio, Marta Comas, Alba Zabalegui, Vanesa Flores, Marina Giralt, Noelia Díaz-Troyano, Roser Ferrer, Ramon Vilallonga, Andreea Ciudin, Betina Biagetti, Impaired accuracy of the dexamethasone suppression test after bariatric surgery: implications for post-surgical cortisol interpretation, European Journal of Endocrinology, Volume 192, Issue 4, April 2025, Pages 346–355, https://doi.org/10.1093/ejendo/lvaf053
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Abstract
The impact of bariatric surgery (BS) on the performance of the 1 mg dexamethasone suppression test (DST) is not well established.
(1) To evaluate the intraindividual results of the DST in a group of patients before and 2 years after BS, and (2) to assess plasma dexamethasone levels and other factors influencing the reliability of the DST.
We conducted a prospective longitudinal study, including 38 subjects evaluating DST before and 2 years after BS. We also compared DST results, plasma dexamethasone levels, and related factors across 3 groups: individuals of the previous cohort 2 years post-BS (n = 21), patients with severe obesity without BS (pwO; n = 10), and healthy controls (n = 7).
Post-BS patients had higher cortisol levels after DST compared with prior (0.9 vs 0.7 µg/dL; P < .01). Four individuals post-BS had cortisol levels >1.8 µg/dL in the absence of autonomous cortisol secretion. Plasma dexamethasone levels were significantly lower in post-BS patients (1.9 ng/dL) compared with non-operated pwO (3.7 ng/dL) and healthy controls (4.0 ng/mL), P < .01. Multivariate analysis identified BS (β = −1.258, P = .01) and sex hormone–binding globulin levels (β = −.013, P = .04) as significant independent predictors of plasma dexamethasone concentrations.
Post-BS subjects showed higher post-DST cortisol levels and reached lower plasma dexamethasone concentration compared with non-operated individuals, which may lead to false-positive results. These findings highlight the need to consider dexamethasone measurements to enhance DST interpretation in post-BS patients. Further studies are necessary to validate these findings in broader populations. The underlying mechanisms need to be explored.
