Questions and Answers
What is Cushing syndrome?
A condition that happens when there is too much cortisol in the body.
What hormone is primarily associated with Cushing syndrome?
Cushing syndrome in children is common.
False
What is the estimated incidence of Cushing disease in children per year?
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What is the most frequent cause of endogenous Cushing syndrome in children?
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What is the main role of cortisol in the body?
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Cushing syndrome represents about _____ to _____ percent of all cases of endogenous Cushing syndrome.
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At what age does Cushing disease reportedly occur in children?
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What are the two types of endogenous Cushing syndrome?
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What is the primary challenge in diagnosing Cushing syndrome in patients?
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Which factor is most significantly associated with ACTH-dependent Cushing syndrome?
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Which of the following conditions is considered a differential diagnosis for adolescents presenting with symptoms of Cushing syndrome?
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In treating Cushing syndrome, which of the following is commonly used as a treatment approach for non-endocrine diseases?
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What is a distinguishing feature of ACTH-independent Cushing syndrome in infants?
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What anomaly is present in adolescent patients with ectopic Cushing syndrome (ECS)?
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Which of the following best describes the incidence of endogenous Cushing syndrome in pediatric patients?
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What is a common symptom that could indicate the presence of Cushing syndrome?
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Which diagnostic method is commonly used as an initial step for diagnosing Cushing syndrome?
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What factor can cause a falsely high result in a 24-hour urinary free cortisol test?
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What is the advantage of using midnight serum cortisol tests in diagnosing Cushing syndrome?
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Which method is preferred for analyzing urine samples in the diagnosis of Cushing syndrome?
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What limitation might affect the collection of urine samples for the 24-hour urinary free cortisol test?
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What is the main purpose of the dexamethasone suppression test (DST) in evaluating Cushing syndrome?
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What non-invasive method is used to test cortisol levels outside of a clinical environment?
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Which of the following is NOT a potential issue with obtaining reliable 24-hour urinary free cortisol results?
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What is the significance of a serum cortisol level of ≥20 µg/dL in relation to Cushing syndrome?
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Which diagnostic test is characterized by a failure of serum cortisol to decrease to 3 after administration?
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What is the recommended first-line treatment for all types of Cushing syndrome?
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What is the success rate for transsphenoidal resection of pituitary tumors in treating Cushing disease?
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What complication is NOT typically associated with surgical intervention for Cushing syndrome?
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How does the success rate of transsphenoidal surgery change over time after the initial procedure?
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What is the implication of a saliva cortisol level greater than 0.13 µg/dL?
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What does an increased observation after stimulation in the low-dose DST suggest?
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Study Notes
Background
- Cushing syndrome in children, also called hypercortisolism, results from excessive cortisol hormone production.
- Cortisol, synthesized from cholesterol, is mainly produced by the zona fasciculata of the adrenal cortex and serves as the primary stress hormone.
- Plays a vital role in the stress response, aiding in gluconeogenesis, tissue repair, regulation of blood pressure, and inflammation reduction.
- Overproduction of cortisol can disrupt puberty and lead to symptoms like growth deceleration, weight gain, and facial plethora.
Epidemiology
- Cushing syndrome is rare in the pediatric population, accounting for 5-10% of all endogenous Cushing syndrome cases.
- Incidence of Cushing disease, driven by ACTH-secreting pituitary adenomas, is estimated at 1-2 cases per million children annually.
- Most affected children are aged 5-15, with a slight female predominance.
- Pediatric cases present distinct characteristics compared to adults; primarily, ACTH overproduction from pituitary adenomas is the most common cause.
- Cortisol action occurs through the glucocorticoid receptor (GR), which regulates genes related to metabolism and immune function when bound by cortisol.
- ACTH production is controlled by corticotropin-releasing hormone (CRH) from the hypothalamus, with pituitary adenomas causing excessive ACTH and subsequent cortisol overproduction.
- Genetic mutations may play a role in Cushing syndrome, particularly in familial syndromes like multiple endocrine neoplasia (MEN) and Carney complex.
Etiology
- Both endogenous and exogenous types of Cushing syndrome are uncommon in pediatric patients, with a roughly even distribution between genders.
- Exogenous or iatrogenic causes, largely due to chronic glucocorticoid or ACTH administration, are the more prevalent triggers.
- Pediatric cases of endogenous Cushing syndrome stem from pituitary adenomas (Cushing disease), adrenal tumors, or ectopic ACTH production.
- Endogenous Cushing syndrome can be categorized into:
- ACTH-dependent: Primarily due to Cushing disease from ACTH-secreting pituitary microadenoma, typically occurs in children aged 7 and older.
- ACTH-independent: Often the cause in infants, associated with adrenal gland issues.
Diagnosis of Cushing Syndrome
- Salivary cortisol is typically measured via liquid chromatography-tandem mass spectrometry (LC-MS/MS) for accuracy in detecting small changes.
- Serum cortisol levels ≥20 µg/dL indicate Cushing syndrome, boasting 99% sensitivity and 100% specificity.
- Salivary levels >0.13 µg/dL are indicative of Cushing syndrome due to abnormalities.
- Low-dose overnight dexamethasone suppression test (DST) assesses serum cortisol failure to decrease to 3, suggesting pituitary ACTH secretion.
- Initial sensitivity of the DST is lower than in adults, but stimulation increases its diagnostic efficacy.
Treatment and Intervention
- Surgical intervention is the first-line treatment for all types of Cushing syndrome.
- For pediatric patients, transsphenoidal resection of pituitary tumors (TSS) is preferred, with a success rate of over 90%.
- Success rates of TSS decrease over time, approximately to 60%, with potential complications including infection, growth hormone deficiency, and hypogonadism.
- Mortality rates within the Cushing syndrome population are low.
Initial Diagnosis in Children
- Accurate classification of Cushing syndrome is vital for effective treatment.
- Evaluation of physical development and medical history informs diagnosis.
- Hypercortisolism is documented through:
- 24-hour urinary free cortisol (UFC)
- Midnight cortisol tests (serum or saliva)
- Dexamethasone suppression test (DST)
- 24-hour UFC tests are usually performed at least two to three consecutive times for accuracy but are hampered by difficulties in urine collection.
- Urine samples are analyzed using LC-MS/MS for their accuracy and ability to minimize interference from medications.
Hormonal Testing
- Midnight serum/salivary cortisol tests evaluate diurnal variations and are obtained through non-invasive methods for saliva and intravenous blood draws for serum.
- Serum cortisol is analyzed using immunoassays like chemiluminescent immunoassay (CLIA) or enzyme-linked immunosorbent assay (ELISA) for high specificity and sensitivity.
Causative Factors and Types
- Common causes of Cushing syndrome include exogenous factors like chronic glucocorticoid administration or ACTH-related disorders.
- Endogenous Cushing syndrome can be subdivided into ACTH-dependent and ACTH-independent types:
- ACTH-dependent typically refers to Cushing disease characterized by overproduction of ACTH due to pituitary microadenomas, prevalent in children ≥7 years old.
- ACTH-independent variations usually arise from adrenal factors in infants, presenting challenges in diagnosis and treatment due to gradual onset.
Ectopic Cushing Syndrome
- Ectopic Cushing syndrome is rare in adolescents, mainly due to ACTH overproduction from neuroendocrine tumors like bronchial carcinoids or thymic tumors.
- Accurate diagnosis often requires ruling out ECS sources to avoid misleading conclusions related to CRH-induced ACTH oversecretion.
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Description
This quiz focuses on Cushing syndrome in children, a critical topic in endocrine biochemistry. It examines the causes, symptoms, diagnosis, and treatment associated with this condition. Students will deepen their understanding of endocrine disorders within the context of children's health.
