Podcast
Questions and Answers
What is the most common endogenous cause of Cushing's syndrome?
What is the most common endogenous cause of Cushing's syndrome?
Which clinical feature is considered most specific to Cushing's syndrome?
Which clinical feature is considered most specific to Cushing's syndrome?
What would indicate a diagnosis of Cushing's syndrome during a Dexamethasone Suppression Test?
What would indicate a diagnosis of Cushing's syndrome during a Dexamethasone Suppression Test?
Identify a laboratory finding commonly associated with Cushing's syndrome.
Identify a laboratory finding commonly associated with Cushing's syndrome.
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Which condition is the most common cause of iatrogenic Cushing's syndrome?
Which condition is the most common cause of iatrogenic Cushing's syndrome?
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In which patient condition would you most likely see central obesity with extremity wasting?
In which patient condition would you most likely see central obesity with extremity wasting?
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Which of the following tumors is specifically associated with ectopic ACTH production?
Which of the following tumors is specifically associated with ectopic ACTH production?
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What is a non-specific clinical feature of Cushing's syndrome?
What is a non-specific clinical feature of Cushing's syndrome?
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Study Notes
Cushing's Syndrome
- Definition: A disorder caused by excessive cortisol production.
Causes
- Latrogenic: Most common. Caused by external administration of glucocorticoids.
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Endogenous: Internal causes
- Cushing's disease: Most common endogenous cause (60-70%). Results from a pituitary tumor.
- Adrenal tumors: Adenomas and carcinomas in the adrenal glands.
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Ectopic ACTH production: Abnormal production of ACTH (adrenocorticotropic hormone) by non-pituitary tumors. Common tumors include:
- Small cell lung cancer (most common)
- Medullary thyroid cancer
- Carcinoid tumors
Clinical Features
- Non-specific: Secondary diabetes (due to gluconeogenesis), hypertension (HTN), osteoporosis (bone breakdown)
- More specific: Central obesity with muscle wasting in extremities, moon-shaped facial appearance.
- Highly specific: Spontaneous bruising, proximal muscle weakness (myopathy), skin stretch marks (striae)
- Other symptoms: Acne, hirsutism (excess hair growth), depression, insomnia, increased susceptibility to infections.
Laboratory Findings
- Hyperglycemia: High blood sugar
- Hypernatremia: High blood sodium
- Hypokalemia: Low blood potassium (from weakened mineralocorticoid function)
- Metabolic alkalosis: Imbalance in body's acid-base levels
Diagnosis
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Step 1: Determining if Cushing's syndrome is present. Several tests may be used:
- Dexamethasone Suppression Test: Measures cortisol levels after dexamethasone administration. Failure to suppress cortisol indicates Cushing's.
- 24-Hour Urinary Free Cortisol: Measures cortisol in a 24-hour urine sample.
- Late-night Salivary Cortisol: Measures cortisol levels in saliva collected late at night.
Dexamethasone Suppression Test (Details)
- Overnight Dexamethasone Suppression Test: 1 mg of dexamethasone taken orally at 11 PM. Serum cortisol level measured at 9 AM.
- Normal Result: Cortisol levels are suppressed (less than 50 nmol/L).
- Abnormal Result: Failure to suppress cortisol levels indicates Cushing's syndrome.
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Description
Explore the causes, clinical features, and implications of Cushing's Syndrome, a disorder characterized by excessive cortisol production. This quiz provides insights into both iatrogenic and endogenous causes, including various tumors, alongside their specific clinical manifestations. Test your knowledge and understanding of this complex endocrine condition.
