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Published on: September 15, 2017
Differences in clinical, hormonal and radiological profile between Cushing's disease and ectopic Cushing's syndrome.
Carmen Gándara Gutiérrez1, Mario Alfredo Saavedra Vásquez2, Eider Pascual-Corrales3
1Endocrinology and Nutrition Department, Hospital Universitario de Cabueñes, Gijon, Spain.
Insights
ACTH-dependent Cushing's syndrome (CS) diagnosis is challenging. Urinary free cortisol (UFC), hypokalemia, metabolic alkalosis, and pituitary adenoma size help differentiate Cushing's disease (CD) from ectopic CS (ECS).
Area of Science:
- Endocrinology
- Internal Medicine
- Diagnostic Medicine
Background:
- ACTH-dependent Cushing's syndrome (CS) presents diagnostic challenges due to clinical variability and complex test interpretation.
- Delayed diagnosis of CS increases patient morbidity.
Purpose of the Study:
- To identify non-invasive clinical, biochemical, and radiological markers for differentiating Cushing's disease (CD) from ectopic ACTH syndrome (ECS).
- To improve diagnostic accuracy for ACTH-dependent CS.
Main Methods:
- Retrospective study of patients with ACTH-dependent CS (2018-2023).
- Analysis of urinary free cortisol (UFC), potassium levels, metabolic alkalosis, and pituitary adenoma size.
Main Results:
- Urinary free cortisol (UFC) levels showed an AUC of 0.812 for differentiating CD and ECS.
- UFC > 4.2x upper limit of normal had 62.5% sensitivity and 90.9% specificity for ECS.
- Pituitary adenoma size (≥4.5mm) had 93.8% sensitivity and 50% specificity for CD.
- Combination of UFC and potassium improved diagnostic accuracy to 85%.
Conclusions:
- Urinary free cortisol (UFC), hypokalemia, metabolic alkalosis, and pituitary adenoma size are key non-invasive parameters for differentiating CD and ECS.
- These markers can aid in the non-invasive diagnosis of ACTH-dependent CS subtypes.
Introduction:
ACTH-dependent Cushing's syndrome (CS) is a diagnostic challenge. Clinical variability and difficult interpretation of diagnostic tests delay diagnosis and increase morbidity.
Objective:
To describe clinical, biochemical and radiological differences in patients with ACTH-dependent CS, with the aim of determining the variables that may help to non-invasively differentiate between Cushing's disease (CD) and ectopic CS (ECS).
Methods:
A retrospective study included patients with ACTH-dependent CS followed at the Ramón y Cajal University Hospital between 2018 and 2023.
Results:
Twenty-eight patients with CD and 9 with ECS were included. Urinary free cortisol (UFC) levels presented an area under the ROC curve (AUC) of 0.812 (95% CI, 0.607-1.000) to differentiate between the two entities. UFC>4.2 times the upper limit of normal showed 62.5% sensitivity and 90.9% specificity for diagnosis of ECS. The differential diagnostic accuracy of potassium level between ECS and CD was 82% (95% CI, 0.598-1.000). The combination of UFC and potassium values increased diagnostic accuracy to 85% (95% CI, 0.586-1.000). 55.6% of patients with ECS presented metabolic alkalosis, compared to 2.8% of those with CD (P=0.001). Pituitary adenoma size presented an AUC of 0.844 (95% CI, 0.59-1.000) for diagnosis of CD. Size≥4.5mm presented 93.8% sensitivity and 50% specificity for the diagnosis of CD.
Conclusions:
UFC, hypokalemia, metabolic alkalosis and pituitary adenoma size are the non-invasive parameters most accurately differentiating between CD and ECS.
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