Endocrine 1 Flashcards
By which four mechanisms can endocrine derangements stem from?
- Impaired hormone synthesis
- Impaired hormone release
- Abnormal hormone-target interaction
- Abnormal target response
What are the three general classifications of endocrine diseases?
- Overproduction
- Underproduction
- Diseases associated with the development of mass lesions
What is the most common cause of hyperpituitarism?
An adenoma of the anterior pituitary.
Describe two characteristics of anterior pituitary adenomas.
- Can be functional (causing symptoms related to excess hormone production) or silent (no symptoms related to excess hormones).
- Most are composed of a single cell type, making one hormone.
What is the most common adenoma of the anterior pituitary that secretes more than one hormone?
One that secretes both GH and prolactin
Name the associated hormone and syndrome with the cell type:
Lactotroph
Prolactin - causes amenorrhea or galactorrhea (milky nipple discharge not associated with pregnancy) in women. Causes hypotension and loss of libido in men.
Name the associated hormone and syndrome with the cell type:
Corticotroph
ACTH and other POMC-derived peptides - causes Cushing and/or Nelson syndrome
Name the associated hormone and syndrome with the cell type:
Gonadotroph
FSH, LH - causes menstrual disturbances in women and loss of libido in men
Name the associated hormone and syndrome with the cell type:
Somatotroph
GH - causes gigantism in prepupertal children and acromegaly in adults
Name the associated hormone and syndrome with the cell type:
Thyrotroph
TSH - causes hyperthyroidism
Name the associated hormone and syndrome with the cell type:
Mammosomatotroph (mixed adenoma)
GH and Prolactin - causes gigantism/acromegaly and amenorrhea and galactorrhea (women) and hypotension and libido loss in men.
Are “hormone negative adenomas” symptomatic?
Nope
What is the difference between a macroadenoma and microadenoma of the pituitary?
Macroadenomas are larger than 1 cm, microadenomas are smaller than 1 cm
Describe the morphology of a pituitary adenoma (3).
- Well-circumscribed and soft.
- May be confined by the sella turcica (a depression in the skull where the pituitary sits).
- Larger lesions extend superiorly through the sellar diaphragm into the suprasellar region and can compress the optic chiasm and adjacent structures.
____% of pituitary adenomas are invasive. Describe these.
30%. They are nonencapsulated and infiltrate adjacent bone, dura, and (uncommonly) the brain.
What is bitemporal hemianopsia and what can cause it? How does this disease cause bitemporal hemianopsia?
It is a type of partial blindness where vision is missing in the outer half of both the right and left visual fields. It can be caused by pituitary adenomas that extend into the suprasellar region and compress the optic chiasm.
Describe the microscopic changes seen in a pituitary adenoma (6).
- Composed of uniform polygonal cells arrayed in sheets, cords, or papillae.
- Sparse CT.
- Not much mitotic activity.
- Cytoplasmic staining is highly varied (acidophilic, basophilic, or chromophobic).
- Cellular monomorphism.
- Absence of a significant reticulin network.
Can the functional status of a pituitary adenoma be reliably predicted from the histologic appearance?
Nope
How do you distinguish a pituitary adenoma from non-neoplastic anterior pituitary parenchyma?
Cellular monomorphism and absence of reticulin network.
What is the most common type of hyperfunctioning pituitary adenoma (50% of cases)?
Prolactinoma
Describe the morphological changes seen in a prolactinoma.
Can vary from microadenomas to macroadenomas. Neoplastic cells stain prolactin-positive.
What are the symptoms of hyperprolactinemia?
Females: amenorrhea, galactorrhea, loss of libido, infertility. More symptomatic in younger women.
Males: decreased libido and impotency.
How are prolactinomas treated?
If large, tumors are removed surgically. Otherwise, bromocriptine (dopamine agonists) inhibit prolactin secretion.
Aside from gigantism/acromegaly, what are seven other symptoms related to GH-producing adenomas?
- Abnormal glucose tolerance.
- DM
- General muscle weakness
- Hypertension
- Arthritis
- Osteoporosis
- CHF
What are the second most common type of functional pituitary adenoma?
GH-producing or GH + prolactin-producing adenomas
Persistent hypersecretion of GH from a pituitary adenoma stimulates ______ secretion of ______ ______ _______ ______.
stimulates hepatic secretion of insulin-like growth-factor.
What is somatomedin C?
synonymous with insulin-like GF
What are the clinical manifestations of acromegaly (9)?
Thick skin, large jaw (prognathism), broad face, separated teeth, arthritis, barrel chest, goiter, male sexual dysfunction, cardiomegaly (hypertension)
Are most ACTH-producing adenomas micro, or macroadenomas?
Microadenomas
What is Nelson syndrome?
After surgical removal of adrenal glands for treatment of Cushing syndrome, lack of negative feedback by cortisol on the AP results in development of aggressive corticotroph cell adenomas.
Loss of ____% of the anterior pituitary as well as destruction of the hypothalamus or hypothalamic-pituitary tract can lead to _________.
75%
all lead to hypopituitarism
What are the six major causes of hypopituitarism?
- Pituitary tumors
- Craniopharyngioma
- Gliomas
- Trauma
- Sheehan syndrome
- Empty sella syndrome
How does a pituitary tumor cause hypopituitarism?
Tumors may be functional or non-functional, but they can compress adjacent tissues and ducts/tracts.
What is a craniopharyngioma?
A benign tumor originating from remnants of the Rathke pouch. Usually located in or above the sella turcica (the bony depression where the pituitary sits)
What is a glioma? How can it cause hypopituitarism?
It is a tumor that starts in the brain or spine (from glial cells) that can destroy the hypothalamus or hypothalamic-pituitary tract.
What is Sheehan syndrome?
When post-partum hypotension from hemorrhage causes ischemic necrosis of the pituitary.
What is Empty sella syndrome?
A flattening or shrinking of the pituitary that occurs when a small anatomical defect above the pituitary gland (of the diaphragma sella) allows CSF to flow into the sella turcica, exhibiting pressure on the gland, causing it to flatten out along the interior walls of the sella turcica cavity. The sella turcica looks empty in images.
Does Empty sella syndrome result in significant endocrine disturbances?
Not really
What are the major clinical manifestations of hypopituitarism in females (5)?
- Pallor from decreased MSH
- Hypothyroidism from decreased TSH
- Failure of lactation due to decreased prolactin
- Adrenal insufficiency due to decreased ACTH
- Ovarian failure due to no FSH, LH
What does diabetes insipidus do to the pituitary?
Causes posterior pituitary syndrome –> deficiency in ADH –> uncontrollable loss of water in urine and hypernatremia (increased sodium concentration) causing polydipsia (thirst)
___% of cases of diabetes insipidus that lead to posterior pituitary syndromes are also associated with brain tumors, especially craniopharyngiomas.
25%
What syndrome involves inappropriate ADH secretion? What can cause it?
Excess of ADH secretion by a malignant neoplasm –> water retention –> hyponatremia, cerebral edema, neurologic dysfunction.
Some causes include psychotropic agents, diuretics, cytostatic agents, or hypothalamic hyperfunction
What type of malignant neoplasm commonly results in paraneoplastic syndrome with inappropriate ADH secretion?
Small cell carcinoma of the lungs
Where in/on the cell are receptors located for peptide hormones?
On the cell surface
Does GH bind to surface receptors, or intracellular receptors?
Surface
Does insulin bind to surface receptors, or intracellular receptors?
Surface
Do steroids hormones bind to surface receptors, or intracellular receptors?
Intracellular receptors
Do glucocorticoids bind to surface receptors, or intracellular receptors?
Intracellular
Do retinoids bind to surface receptors, or intracellular receptors?
intracellular
Does thyroxine bind to surface receptors, or intracellular receptors?
Intracellular
