Decreased maximal cortisol secretion rate in patients with cirrhosis: Relation to disease severity

Adrenal insufficiency in liver diseases - pathophysiology and underlying mechanisms

Relative adrenal insufficiency (RAI) is common in critically ill patients with cirrhosis, but it has been also documented in non-critically ill patients. Its pathophysiology is complex and not well understood yet. In this review, we aimed to present potential mechanisms and causal pathways implicated in the pathogenesis of RAI in cirrhosis. There is accumulating evidence supporting a suboptimal baseline adrenal function in cirrhosis mainly due to decreased cortisol synthesis and metabolism rates from the adrenal gland. Apart from this peripheral impairment, more recent studies suggest that there is a greater defect in the central stimulation of the hypothalamic-pituitary-adrenal (HPA) axis (hypothalamus/pituitary gland). Pro-inflammatory mediators, which are elevated in cirrhosis, have been also implicated through suppression of the HPA axis, decrease in cortisol synthesis and tissue glucocorticoid resistance. All abovementioned support the hepatoadrenal syndrome hypothesis that during episodes of acute decompensation there is suboptimal adrenocortical response that leads to worse outcomes. In conclusion, the complex pathophysiology of adrenal dysfunction in cirrhosis has not been fully elucidated yet and further research is needed in order to better understand this rather common entity in cirrhosis.

Overdiagnosis of adrenal insufficiency in children with biliary atresia

Serum cortisol mainly binds to the cortisol-binding globulin (CBG). Children with biliary atresia (BA) may have low serum CBG levels; thus, low serum total cortisol (TC) levels and adrenal insufficiency (AI) may be overdiagnosed. This study aimed to assess adrenal function in children with BA. All the patients underwent adrenocorticotropic hormone (ACTH) stimulation tests. Plasma ACTH, serum TC, and CBG levels were measured at baseline, with additional TC measurements at 30 and 60 min during testing. Free cortisol (FC) index (FCI) and calculated FC (cFC) were also calculated. AI was defined as peak TC <500 nmol/L (<18 μg/dL), peak FCI <12 nmol/mg, or peak cFC <33 nmol/L (<1.2 μg/dL). This study enrolled 71 children with BA. The Median (IQR) age of the patients was 5.5 (1.7-11.4) years. Twenty-five (35%) patients were diagnosed with AI based on the peak TC. In the AI group, the median serum CBG level was significantly lower than that in the non-AI group (481 vs. 533 nmol/L, p = 0.03). Only eight patients (11%) met all three AI criteria (six secondary AI and two primary AI). In conclusion, low serum CBG levels contribute to reduced peak TC and, consequently, overdiagnosing AI. Peak FCI and cFC could help reduce the overdiagnosis of AI.

Four-Compartment Diffusion Model of Cortisol Disposition: Comparison With 3 Alternative Models in Current Clinical Use

Context

Estimated rates of cortisol elimination and appearance vary according to the model used to obtain them. Generalizability of current models of cortisol disposition in healthy humans is limited.

Objective

Development and validation of a realistic, mechanistic model of cortisol disposition that accounts for the major factors influencing plasma cortisol concentrations in vivo (Model 4), and comparison to previously described models of cortisol disposition in current clinical use (Models 1-3).

Methods

The 4 models were independently applied to cortisol concentration data obtained for the hydrocortisone bolus experiment (20 mg) in 2 clinical groups: healthy volunteers (HVs, n = 6) and corticosteroid binding globulin (CBG)-deficient (n = 2). Model 4 used Fick's first law of diffusion to model free cortisol flux between vascular and extravascular compartments. Pharmacokinetic parameter solutions for Models 1-4 were optimized by numerical methods, and model-specific parameter solutions were compared by repeated measures analysis of variance. Models and respective parameter solutions were compared by mathematical and simulation analyses, and an assessment tool was used to compare performance characteristics of the four models evaluated herein.

Results

Cortisol half-lives differed significantly between models (all P < .001) with significant model-group interaction (P = .02). In comparative analysis, Model 4 solutions yielded significantly reduced free cortisol half-life, improved fit to experimental data (both P < .01), and superior model performance.

Conclusion

The proposed 4-compartment diffusion model (Model 4) is consistent with relevant experimental observations and met the greatest number of empiric validation criteria. Cortisol half-life solutions obtained using Model 4 were generalizable between HV and CBG-deficient groups and bolus and continuous modes of hydrocortisone infusion.

Adrenal insufficiency in cirrhosis

Hypothalamus-pituitary-adrenal axis assessment in patients with cirrhosis is challenging. The phenotype of fatigue, hypotension, electrolyte disarray, and abdominal pain characterizing primary adrenal insufficiency (AI) overlaps significantly with decompensated liver disease. Reliance on total cortisol assays in hypoproteinemic states is problematic, yet abnormal stimulated levels in cirrhosis are associated with poor clinical outcomes. Alternative measures including free plasma or salivary cortisol levels have theoretical merit but are limited by unclear prognostic significance and undefined cirrhosis-specific reference ranges. Further complicating matters is that AI in cirrhosis represents a spectrum of impairment. Although absolute cortisol deficiency can occur, this represents a minority of cases. Instead, there is an emerging concept that cirrhosis, with or without critical illness, may induce a “relative” cortisol deficiency during times of stress. In addition, the limitations posed by decreased synthesis of binding globulins in cirrhosis necessitate re-evaluation of traditional AI diagnostic thresholds.

Interpretation of Abnormal Dexamethasone Suppression Test is Enhanced With Use of Synchronous Free Cortisol Assessment

CONTEXT

Interpretation of dexamethasone suppression test (DST) may be influenced by dexamethasone absorption and metabolism and by the altered cortisol binding.

OBJECTIVE

We aimed to determine the normal ranges of free cortisol during DST in participants without adrenal disorders and to identify the population of patients where post-DST free cortisol measurements add value to the diagnostic workup.

DESIGN AND SETTING

Cross-sectional study conducted in a tertiary medical center.

PARTICIPANTS

Adult volunteers without adrenal disorders (n = 168; 47 women on oral contraceptive therapy [OCP], 66 women not on OCP, 55 men) and patients undergoing evaluation for hypercortisolism (n = 196; 16 women on OCP).

MEASUREMENTS

Post-DST dexamethasone and free cortisol (mass spectrometry) and total cortisol (immunoassay).

MAIN OUTCOME MEASURES

Reference range for post-DST free cortisol, diagnostic accuracy of post-DST total cortisol.

RESULTS

Adequate dexamethasone concentrations (≥0.1 mcg/dL) were seen in 97.6% volunteers and 96.3% patients. Only 25.5% of women volunteers on OCP had abnormal post-DST total cortisol (>1.8 mcg/dL). In volunteers, the upper post-DST free cortisol range was 48 ng/dL in men and women not on OCP, and 79 ng/dL in women on OCP. When compared with post-DST free cortisol, diagnostic accuracy of post-DST total cortisol was 87.3% (95% CI, 81.7-91.7); all false-positive results occurred in patients with post-DST cortisol between 1.8 and 5 mcg/dL. OCP use was the only factor associated with false-positive results (21.1% vs 4.9%, P = 0.02).

CONCLUSIONS

Post-DST free cortisol measurements are valuable in patients with optimal dexamethasone concentrations and post-DST total cortisol between 1.8 and 5 mcg/dL.