Cushing's syndrome resident survival guide: Difference between revisions
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==Don'ts== | ==Don'ts== | ||
* The | * The 24 hours urinary free cortisol measurement should not be used for diagnosis in subclinical hypercortisolism (mild hypercortisolism in adrenal incidentaloma) as it can yield false-negative results. False-positive results are present in patients with physiological hypercortisolism (patients with a polycystic ovarian syndrome or major depressive disorder). High fluid intake can result in an increased fraction of excretion of free cortisol yielding false-positive results. | ||
* MRI is not a cost-effective diagnostic test. CT scan of the abdomen and adrenal glands is preferred as an imaging test to localize adrenal adenoma or carcinoma compared to MRI. | |||
==References== | ==References== |
Revision as of 09:52, 20 August 2020
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
This section provides a short and straight to the point overview of the disease or symptom. The first sentence of the overview must contain the name of the disease.
Causes
Life Threatening Causes
Life-threatening causes include conditions that may result in death or permanent disability within 24 hours if left untreated.
- Does not include any known cause.
Common Causes
- Iatrogenic or factitious Cushing's syndrome due to administration of exogenous glucocorticoids.
- Cushing's disease (due to excess secretion of Adrenocorticotropic hormone from anterior pituitary).
- Paraneoplastic: due to ectopic secretion of ACTH (includes, small cell lung cancer, benign carcinoid tumors, Ewing's sarcoma).
- Ectopic secretion of Corticotropin-releasing hormone (CRH).
- Adenoma and carcinoma in the adrenal cortex
- Primary pigmented nodular adrenocortical disease (PPNAD)
- Bilateral macronodular adrenal hyperplasia (BMAH)
Diagnosis
Shown below is an algorithm summarizing the diagnosis of Cushing's syndrome according to the Endocrine Society clinical guidelines.
Symptoms suggestive of Cushing’s syndrome:
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Take a detailed history of the patient including medication history. Rule out the use of any exogenous topical, oral, parenteral, or inhaled glucocorticoid and synthetic progesterone. | |||||||||||||||||||||||||||||||||||||
Perform any two of the following three laboratory investigations:
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Two of the following abnormal results:
| Any one abnormal result | ||||||||||||||||||||||||||||||||||||
High suspicion for Cushing's syndrome | Low suspicion for Cushing's syndrome | ||||||||||||||||||||||||||||||||||||
Measure late night plasma ACTH levels | Refer to endocrinologist | ||||||||||||||||||||||||||||||||||||
Low value plasma ACTH <5 pg/mL | Indeterminate values of plasma ACTH between 5 to 20 pg/mL | High value plasma ACTH >20 pg/mL | |||||||||||||||||||||||||||||||||||
CRH or desmopressin stimulation test | |||||||||||||||||||||||||||||||||||||
No ACTH response | + ACTH response | ||||||||||||||||||||||||||||||||||||
ACTH independent Cushing's syndrome | ACTH dependent Cushing's syndrome | ||||||||||||||||||||||||||||||||||||
CT scan/ MRI of adrenal glands to look for adrenal tumors or hyperplasia. | Perform both tests:
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Adequate suppresion of early morning serum cortisol (with levels less than 5 mcg/dL) and stimulation with CRH | Negative or equivocal response | ||||||||||||||||||||||||||||||||||||
MRI of the pituitary | |||||||||||||||||||||||||||||||||||||
Tumor >6mm | Tumor <6mm or no mass lesion | ||||||||||||||||||||||||||||||||||||
Cushing's disease | Perform Inferior petrosal sinus sampling. | ||||||||||||||||||||||||||||||||||||
Central step-up | No Central step-up | ||||||||||||||||||||||||||||||||||||
Ectopic ACTH production | |||||||||||||||||||||||||||||||||||||
Treatment
Shown below is an algorithm summarizing the treatment of Cushing's syndrome according the the Endocrine Society clinical practice guidelines.
The treatment depends upon the underlying etiology | |||||||||||||||||||||||||||||||||||||||||||||||
Cushing's disease | Paraneoplastic Cushing's syndrome | ACTH-independent Cushing's syndrome | |||||||||||||||||||||||||||||||||||||||||||||
Transsphenoidal surgery: Treatment of choice in patients with pituitary adenoma with distinct margins. | Resectable tumor | Nonresectable tumor | Adrenal adenoma | Bilateral adrenal hyperplasia | |||||||||||||||||||||||||||||||||||||||||||
Resection of the primary tumor | Medical therapy:
| Unilateral adrenalectomy | Bilateral adrenalectomy | ||||||||||||||||||||||||||||||||||||||||||||
Bilateral adrenalectomy is performed in patients with severe refractory hypercortisolism despite surgical and radiation therapy | |||||||||||||||||||||||||||||||||||||||||||||||
Do's
- In ACTH-independent Cushing’s syndrome, glucocorticoid therapy should be given to patients post-operatively due to suppression of the hypothalamic-pituitary axis. Patients with medication-induced Cushing’s syndrome should taper the dose of glucocorticoid instead of sudden withdrawal of the medications.
- Thromboprophylaxis should be initiated preoperatively in patients with Cushing’s syndrome. There is a hypercoagulable state in patients with Cushing’s syndrome due to impaired fibrinolysis and activation of the coagulation cascade. These patients have an increased risk of developing deep venous thrombosis compared to the normal patient population.
- Rebound thymic hyperplasia can occur in patients whose hypercortisolism is controlled. On the chest imaging, it is seen as a mass in the anterior mediastinum and can be misinterpreted as tumor recurrence, or metastasis.
Don'ts
- The 24 hours urinary free cortisol measurement should not be used for diagnosis in subclinical hypercortisolism (mild hypercortisolism in adrenal incidentaloma) as it can yield false-negative results. False-positive results are present in patients with physiological hypercortisolism (patients with a polycystic ovarian syndrome or major depressive disorder). High fluid intake can result in an increased fraction of excretion of free cortisol yielding false-positive results.
- MRI is not a cost-effective diagnostic test. CT scan of the abdomen and adrenal glands is preferred as an imaging test to localize adrenal adenoma or carcinoma compared to MRI.