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Questions and Answers
What is the effect of pasireotide on ACTH levels in Cushing disease?
What is the effect of pasireotide on ACTH levels in Cushing disease?
Which medication is used to treat high blood sugar associated with Cushing syndrome?
Which medication is used to treat high blood sugar associated with Cushing syndrome?
What is the normal prolactin level?
What is the normal prolactin level?
What is the typical prolactin level that signals a prolactinoma?
What is the typical prolactin level that signals a prolactinoma?
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What is a symptom of hyperprolactinemia?
What is a symptom of hyperprolactinemia?
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What is a cause of hyperprolactinemia?
What is a cause of hyperprolactinemia?
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What is a treatment option for Cushing disease?
What is a treatment option for Cushing disease?
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What is a medication that can cause hyperprolactinemia?
What is a medication that can cause hyperprolactinemia?
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What is the diagnostic test for hyperprolactinemia?
What is the diagnostic test for hyperprolactinemia?
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What is a type of prolactinoma?
What is a type of prolactinoma?
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Study Notes
SIADH (Syndrome of Inappropriate Anti-Diuretic Hormone)
- Results from malignancies, damage to the hypothalamus or pituitary, disrupting the feedback loop regulating ADH
- Leads to excess water reabsorption, dilutional hyponatremia, and decreased serum osmolality
- Symptoms:
- Lethargy and weakness
- Confusion or changes in neurological status
- Cerebral edema
- Muscle cramps
- Decreased urine output
- Weight gain without edema
- Assessment:
- Serum sodium: low
- Serum osmolality: low
- Urine osmolality: disproportionately elevated
- Urine specific gravity: elevated
- Plasma ADH: elevated
- Treatment:
- Treat underlying cause
- Hypertonic or isotonic IV solution
- Monitor for signs of fluid and electrolyte imbalance
- Monitor for neurological effects
- Restrict fluid intake
- Lithium: inhibits ADH to promote water excretion
Diabetes Insipidus (DI)
- Hypofunction of posterior pituitary
- Can occur with damage to the hypothalamus or pituitary (neurogenic DI) or defect in renal tubules (nephrogenic DI)
- Decreased production or release of ADH results in massive water loss, leading to hypovolemic dehydration
- Clinical manifestations:
- Polyuria (more than 3 liters per 24 hours in adults)
- Urine specific gravity: low
- Polydipsia (excessive drinking)
- Weight loss
- Dry skin and mucous membranes
- Possible hypovolemia, hypotension, and electrolyte imbalance
- Diagnostic tests:
- Serum sodium
- Urine specific gravity
- Serum osmolality
- Urine osmolality
- Serum ADH levels
- Vasopressin test and water deprivation test: increased hyperosmolality is diagnostic for DI
Pituitary Gland Anatomy
- Located at the base of the brain, in a small depression of the sphenoid bone (sella turcica)
- Purpose: controls the activity of many other endocrine glands ("master gland")
- Two lobes: anterior and posterior
- Anterior lobe:
- Glandular tissue (75% of total weight)
- Hormones controlled by regulating hormones from the hypothalamus
- Produces GH, ACTH, TSH, PRL, FSH, LH, and MSH
- Posterior lobe:
- Nerve tissue
- Contains axons originating in the hypothalamus
- Stores and releases hormones produced by the hypothalamus
- Produces ADH and OT
Pituitary Gland Hormones
- Anterior pituitary hormones:
- GH (growth hormone)
- ACTH (adrenocorticotropic hormone)
- TSH (thyroid-stimulating hormone)
- PRL (prolactin)
- FSH (follicle-stimulating hormone)
- LH (luteinizing hormone)
- MSH (melanocyte-stimulating hormone)
- Posterior pituitary hormones:
- ADH (anti-diuretic hormone, vasopressin)
- OT (oxytocin)
Hyperpituitarism and Hypopituitarism
- Hyperpituitarism: pathologic consequences of pituitary disorders, including:
- Hypersecretion of one hormone, commonly PRL, ACTH, or GH
- Local compression of brain tissue by expanding tumor
- Hypopituitarism: deficiency of one or more pituitary hormones, leading to:
- Hyposomatotropism (growth hormone deficiency)
- Hypothyroidism (thyroid-stimulating hormone deficiency)
- Adrenal insufficiency (adrenocorticotropic hormone deficiency)
Acromegaly and Gigantism
- Acromegaly: excessive growth hormone secretion in adulthood, leading to:
- Coarsening of facial features
- Enlarged hands and feet
- Prognathism
- Carpel tunnel syndrome
- Excessive sweating and oily skin
- Headache and vision disturbance
- Sleep apnea
- General tiredness
- Oligomenorrhea or amenorrhea
- Impotence
- Gigantism: excessive growth hormone secretion in childhood, leading to:
- Abnormally tall stature
- Body proportions are normal
- Diagnosis:
- History and physical exam
- Ask about size of hats, shoes, old pictures, and organomegaly
- Examine for complications like HTN, DM, CVS cardiomegaly, and COLON TUMOURS
- Investigation:
- GH analysis (glucose tolerance, OGTT)
- Prolactin levels and other pituitary function tests
- MRI or CT and visual field tests to determine size and position of the adenoma
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Description
This quiz covers the pathophysiology and symptoms of Syndrome of Inappropriate Antidiuretic Hormone (SIADH), including causes, signs, and symptoms such as lethargy, confusion, and decreased urine output. Understand the effects of SIADH on the body, including dilutional hyponatremia and cerebral edema.
