### Title of the article

Overnight 1-mg DST Serum Cortisol in Various Stages of Chronic Kidney Disease—Normative Data and Underlying Mechanisms

First two Authors followed by et al

Robin Garg, Saba Samad Memon, et al.

One line summary of the article

The study establishes normative ranges of overnight dexamethasone suppression test (ONDST) cortisol levels across different stages of chronic kidney disease (CKD) and investigates underlying mechanisms for altered cortisol levels.

Six key points from the article

  1. Normative Data: Established normative ranges of ONDST serum cortisol for CKD stages with 95th percentiles: 1.2 (controls), 3.0 (G2), 3.2 (G3a), 4.3 (G3b), 4.7 (G4), 5.7 (G5), and 7.1 µg/dL (G5D).

  2. Cortisol Correlation: Post-ONDST cortisol levels inversely correlated with estimated glomerular filtration rate (eGFR).

  3. Exploratory Findings: In the exploratory cohort, 8 AM cortisol and ACTH levels were similar among controls and CKD patients, but ONDST ACTH was slightly higher in G5/5D vs. controls.

  4. Assay Interference: ONDST cortisol levels were higher in CKD patients when measured by chemiluminescent immunoassay (CLIA) compared to liquid chromatography–tandem mass spectrometry (LC-MS/MS), indicating assay interference.

  5. Dexamethasone Bioavailability: Dexamethasone levels post-ONDST were adequate and similar across all groups, suggesting that altered cortisol metabolism, not dexamethasone bioavailability, affects ONDST results in CKD.

  6. Cortisol Half-life: Significant drop in post-ONDST cortisol from 8 AM to 4 PM was observed in controls and G3b/4, but not in G5/5D, indicating prolonged cortisol half-life in severe CKD stages.

Practical take-home message

When evaluating Cushing syndrome in CKD patients, consider the eGFR-based normative ranges for ONDST cortisol levels and be aware of potential assay interferences and prolonged cortisol half-life.

Citation for the article in Vancouver format

Garg R, Memon SS, Lila A, et al. Overnight 1-mg DST Serum Cortisol in Various Stages of Chronic Kidney Disease—Normative Data and Underlying Mechanisms. J Endocr Soc. 2024;8(3):1-8. doi:10.1210/jendso/bvae002

Toolkit

You can find the tool to help you in the calculation here: Garg-Memon Tool