ECE2018 Poster Presentations: Pituitary and Neuroendocrinology Pituitary - Clinical (101 abstracts)
1Endocrinology Unit, Fondazione IRCCS Ca Granda Ospedale Maggiore Policlinico, Milan, Italy; 2University of Milan, Milan, Italy; 3Department of Clinical Sciences and Community Health University of Milan, Milan, Milan, Italy; 4Laboratorio Analisi, Fondazione IRCCS Ca Granda Ospedale Maggiore Policlinico, Milano, Milan, Italy.
Objective: The current cut-offs to diagnose adrenal insufficiency (AI) have been established using outdated immunoassays. More modern methods have demonstrated less cross-reactivity with other steroids. The aim of our study was to evaluate the correlation between the cortisol assay Roche Cortisol I (R1), the newly available Roche Cortisol II (R2) and liquid chromatography tandem mass spectrometry (LC-MS/MS), the gold standard procedure for the measurement of steroids.
Design: We enrolled 30 consecutive patients (age 47±21 years) referred to our Center to undergo Synacthen test (1 or 250 μg). Blood samples were collected at 0, 30 and 60 minutes and cortisol was simultaneously measured with R1, R2 and LC-MS/MS. AI was diagnosed for R1 stimulated peak cortisol levels <18 μg/dl.
Results: Mean cortisol levels measured with R1, R2 and LC-MS/MS were respectively 14.9±6.4, 10.4±4.3 and 10.7±4.3 μg/dl at basal conditions, 25.5±7.4, 17.4±4.8 and 18.1±4.8 μg/dl at 30 minutes, 26.7±10.9, 18.2±7.1 and 18.8±7.3 at 60 min after Synacthen test (P≤0.01 for R1 vs both R2 and LC-MS/MS; P=not significant for R2 vs LC-MS/MS at any time). Based on the correlation between R1 and R2 cortisol levels we calculated that the diagnostic threshold for AI would be 12.6 μg/dl if cortisol is measured with R2. Considering the 18 μg/dl cut-off AI was diagnosed in 5/30 patients using R1 and 12/30 using R2 (+140%).
Conclusions: The introduction of more specific cortisol assays results in lower cortisol levels and could lead to wrong diagnosis of AI. Cortisol levels by R2 method are similar to those found by LC-MS/MS. It could help clinician in the Synacthen test interpretation until new clinically-derived thresholds will be available.