Diagnosis of Cushing Syndrome

Overview

• Cushing syndrome results from exposure to excess glucocorticoids.
• Can be exogenous (corticosteroids) or endogenous (autonomous cortisol overproduction).
• Early diagnosis is crucial due to significant morbidity and mortality.
• Challenges in diagnosis due to similarity with other conditions like pseudo-Cushing syndrome.

Screening and Diagnosis

• Initial Workup: Exclude corticosteroid use first.
• First-line Screening Tests:
  • 1-mg Dexamethasone Suppression Test (DST)
  • 24-hour Urinary Free Cortisol (UFC)
  • Late-night Salivary Cortisol Measurement
• Scalp-hair Analysis: For long-term glucocorticoid exposure.

ACTH-dependent vs. ACTH-independent

• Plasma ACTH Concentrations:
  • ACTH-dependent (80%-85%)
  • ACTH-independent (15%-20%)
• Imaging & Testing:
  • MRI for pituitary adenomas.
  • Bilateral Inferior Petrosal Sinus Sampling (BIPSS) for differentiation.

Case Studies

Case 1: Pseudo-Cushing Syndrome

• Symptoms: Weight gain, central obesity, muscle weakness, insomnia.
• Tests: UFC, disturbed DST, ACTH measurements.
• Diagnosis: Pseudo-CS due to psychiatric disorder and nonfunctional pituitary lesion.

Case 2: Pituitary-dependent Cushing Syndrome

• Symptoms: Nephrolithiasis, hypertension, weight gain, hirsutism.
• Tests: UFC, DST, ACTH measurements, MRI showing pituitary adenoma.
• Treatment: Transsphenoidal adenomectomy.

Comorbidities

• Hypertension, hyperlipidemia, insulin resistance, obesity, hypercoagulability.
• Cardiovascular diseases, osteoporosis, neuropsychiatric issues.
• Increased risk of infections and other complications.

New Diagnostic Techniques

Hair Cortisol Measurement

• Non-invasive, long-term assessment of cortisol exposure.
• Can identify cyclical Cushing syndrome and subclinical cases.

Imaging and Molecular Techniques

• High-resolution MRI, BIPSS.
• Gallium-68 PET-CT for detection of corticotroph adenomas.

Cushing Syndrome in Pregnancy

• Rare due to hypercortisolism affecting ovulation.
• Mostly caused by adrenal adenomas.
• Challenges in diagnosis due to overlap with pregnancy symptoms.

Conclusion

• Early diagnosis and differentiation of causes is critical.
• Awareness and screening among physicians treating comorbidities can aid in early detection.
• Continuous advancements in diagnostic techniques are improving detection and management.