Assessment of 1 mg Dexamethasone Suppression Test in Patients with Obesity Before Bariatric Surgery

Pre-Surgery Cortisol Levels as Biomarker of Evolution after Bariatric Surgery: Weight Loss and Weight Regain

Background: Bariatric surgery (BS) is effective for achieving significant weight loss. However, weight regain (WR) is an emerging problem. Objective: To assess the prognostic value of morning serum cortisol, a 1 mg dexamethasone suppression test (DST), 24 h urinary free cortisol (UFC) and late-night salivary cortisol (LNSC) in a cohort of patients with severe obesity (pwSO) undergoing BS in terms of weight loss and WR. Methods: Patients scheduled for BS underwent the following procedures at baseline, 12 months and 24 months after BS: medical history, anthropometric data, blood analysis and cortisol tests. We evaluated total weight loss (TWL) ≥ 30% at 1 year and WR after 2 years as an increase of ≥10% of the maximum weight lost. Results: In total, 142 subjects were included; 101 (71.1%) were females and the mean age was 45.9 ± 9.2 years. Up to 76.8% of subjects achieved ≥30% TWL, without statistically significant differences in DST results or morning serum cortisol, UFC or LNSC levels. However, a higher pre-surgery morning serum cortisol level was a significant predictor of a WR ≥ 10% (cortisol 17.8 [IQR 13.1-18.5] vs. 12.0 [IQR 8.8-15.8] μg/dL; p < 0.01); OR of 1.216 (95% CI 1.069-1.384); AUC [0.761, CI: (0.616-0.906); p < 0.01]. A cut-off value of cortisol > 13.0 μg/dL was predictive of a WR ≥ 10% (sensitivity 0.71; specificity 0.63). Conclusions: No cortisol test was useful in predicting weight loss; however, the pre-surgery morning serum cortisol level was able to predict a WR ≥ 10% in a cohort of pwSO 2 years after BS. A cut-off value of cortisol > 13 μg/dL might be an easy tool to identify patients at higher risk of WR, enabling healthcare providers to implement tailored, long-term strategies to minimize this outcome.

Cushing's syndrome screening with the 1-mg dexamethasone suppression test in metabolically healthy and unhealthy obesity phenotypes

BACKGROUND

The ongoing debate regarding the need for screening Cushing's syndrome (CS) in patients with obesity continues. The objectives of this study were to establish the prevalence of CS in the population with obesity and assess how metabolic health status influences cortisol levels following the 1 mg dexamethasone suppression test (DST).

METHODS

This retrospective study included 1008 patients with obesity who underwent screening with the 1 mg DST for CS. These patients were categorized into two groups as metabolically healthy obesity (MHO) and unhealthy obesity (MUO).

RESULTS

Out of the 1008 patients, 779 (77.3%) belonged to the MUO group. Within the entire study cohort, 12 (1.2%) patients exhibited a cortisol level of ≥ 1.8 after the 1 mg DST. Cortisol levels following the 1 mg DST were also significantly higher in the MUO group than in the MHO group (p = 0.001). Among these 12 patients, 11 were presenting a MUO phenotype. Hypercortisolism was definitively diagnosed in two patients, resulting in an overall prevalence of 0.2%. The 1 mg DST demonstrated a specificity of 99% and 100% sensitivity for screening for CS.

CONCLUSIONS

While the 1 mg DST is a practical screening test for CS with high specificity in obesity, the number of CS cases detected remains relatively low. Therefore, it may be more reasonable and applicable to screen patients with MUO phenotype rather than all individuals with obesity.

Assessment of the diagnostic performance of the 1 mg dexamethasone suppression test in class 3 obese patients

Objective. This study was aimed to evaluate the prevalence of Cushing’s syndrome and the diagnostic performance of the 1 mg dexamethasone suppression test in class 3 obese patients.

Methods. Anthropometric measurements and other laboratory data, including 1 mg dexamethasone suppression test of 753 class 3 obese patients, who applied to the Endocrinology and Metabolism Outpatient Clinic for the pre-bariatric surgery evaluation between 2011 and 2020, were evaluated retrospectively.

Results. An abnormal response to the 1 mg dexamethasone suppression test (cortisol ≥1.8 mcg/dl) was observed in 24 patients and the presence of Cushing’s syndrome was confirmed by additional tests in 6 patients. The prevalence of abnormal dexamethasone suppression test was 3.18% and the prevalence of Cushing’s syndrome 0.79%. The specificity value was determined as 97.5% for 1 mg dexamethasone suppression test with cortisol threshold value ≥1.8 mcg/dl.

Conclusions. The prevalence of Cushing’s syndrome was found to be low in class 3 obese patients and 1 mg of dexamethasone suppression test had a very sufficient performance for Cushing’s syndrome screening in this patient group.

Overnight 1 mg dexamethasone suppression test and 24 h urine free cortisol-accuracy and pitfalls when screening for Cushing's syndrome

Diagnosis of Cushing's syndrome (CS) is often delayed due to variable clinical features and its rarity. Simple and accurate screening tests are required to enhance screening for hypercortisolism. Both overnight 1 mg dexamethasone suppression test (DST) and urinary free cortisol (UFC) demonstrate high sensitivity and specificity for the diagnosis of CS. However, each test has its own distinctive features, making it preferable in specific clinical conditions. This review will discuss the pitfalls for each of those tests.

Consensus statement by the French Society of Endocrinology (SFE) and French Society of Pediatric Endocrinology & Diabetology (SFEDP) on diagnosis of Cushing's syndrome

Cushing's syndrome is defined by prolonged exposure to glucocorticoids, leading to excess morbidity and mortality. Diagnosis of this rare pathology is difficult due to the low specificity of the clinical signs, the variable severity of the clinical presentation, and the difficulties of interpretation associated with the diagnostic methods. The present consensus paper by 38 experts of the French Society of Endocrinology and the French Society of Pediatric Endocrinology and Diabetology aimed firstly to detail the circumstances suggesting diagnosis and the biologic diagnosis tools and their interpretation for positive diagnosis and for etiologic diagnosis according to ACTH-independent and -dependent mechanisms. Secondly, situations making diagnosis complex (pregnancy, intense hypercortisolism, fluctuating Cushing's syndrome, pediatric forms and genetically determined forms) were detailed. Lastly, methods of surveillance and diagnosis of recurrence were dealt with in the final section.

Biochemical diagnosis of Cushing's disease: Screening and confirmatory testing

Due to the variable clinical features and its rarity diagnosis of Cushing's disease (CD) is often delayed. Clearly, awareness for CD needs to be raised, accompanied by the availability of simple and accurate screening tests. Late-night salivary cortisol (LNSC), 1 mg dexamethasone suppression test (DST), and urinary free cortisol (UFC) have all been extensively studied, demonstrating high sensitivity and specificity for the diagnosis of Cushing's syndrome. However, each of those well-established tests has its own distinctive features, making it preferable in specific clinical conditions and patient groups. To choose the most appropriate test in individual patients, an expert endocrinologist should be consulted. This review will discuss the pitfalls for each of those tests.