Hypothalamic-Pituitary-Adrenal Axis Activity and Metabolic Disorders in Kidney Transplant Recipients on Long-Term Glucocorticoid Therapy

<b>Background/Objectives:</b> Glucocorticoids are commonly used for maintenance immunosuppressive therapy in kidney transplant recipients (KTRs). We aimed to investigate the prevalence of hypothalamic-pituitary-adrenal (HPA) axis suppression and its association with metabolic disorders in stable KTRs on low-dose glucocorticoids. <b>Methods</b>: This cross-sectional study included adult KTRs on low-dose glucocorticoids. HPA axis suppression was defined as baseline morning cortisol < 5 μg/dL. Adrenocorticotropic hormone (ACTH), dehydroepiandrosterone-sulphate (DHEAS) and 24 h urinary free cortisol (UFC) levels were also assessed. Examined metabolic disorders included hypertension, dyslipidemia, central obesity and post-transplant diabetes mellitus (PTDM). <b>Results</b>: Eighty adult KTRs with a median 57 months (IQR 24-102) since transplantation were included in the study. The mean prednisolone dose was 5.0 ± 1.3 mg/day. Baseline cortisol < 5.0 μg/dL was observed in 27.5% of the KTRs. Participants with baseline cortisol < 5.0 μg/dL were older (55.1 vs. 47.4 years, <i>p</i> = 0.023) and had had a transplant for a longer time (101.4 vs. 67.0 months, <i>p</i> = 0.043), compared with the rest of the cohort. Baseline cortisol correlated positively with ACTH (rho = 0.544, <i>p</i> < 0.001), DHEAS (rho:0.459, <i>p</i> < 0.001) and UFC (rho: 0.377, <i>p</i> = 0.002). The area under the receiver-operating characteristic curve for ACTH as a predictor of baseline cortisol > 5.0 μg/dL was 0.79 [95% confidence interval (CI): 0.68-0.89]. After adjustment for covariates, HPA axis suppression was not associated with the examined metabolic disorders. <b>Conclusions</b>: Our study showed that stable KTRs on chronic low-dose glucocorticoids exhibited an increased prevalence of HPA axis suppression. ACTH may serve as a surrogate biomarker for HPA axis activity in this population. Further research could evaluate the association of glucocorticoid-induced HPA axis inhibition with metabolic disorders.