15.1-15.7 Endocrine Flashcards
What is the mechanism by which a pituitary tumor produces bitemporal hemianopsia?
Compression of the optic chiasm
What are the problems that a nonfunctional pituitary adenoma can cause? (3)
- Bitemporal hemianopsia
- Hypopituitarism
- HA
What is the most common type of functional pituitary adenoma?
Prolactinoma
What are the s/sx of a prolactinoma in males? Females?
Males = Decreased libido and HA Females = galactorrhea and amenorrhea
What is the treatment for a prolactinoma?
Dopamine agonists or surgery
Why do prolactinomas cause amenorrhea?
Prolactin inhibits the synthesis and release of GnRH
Why don’t males have galactorrhea with prolactinomas?
They do not have the terminal ducts necessary
What is the treatment for prolactinoma? Why?
Dopamine agonist, (e.g. bromocriptine) since dopamine inhibits the release of prolactin
What are the s/sx of GH adenomas in children? Adults? What other endocrine problem can be seen?
- Gigantism in children
- Acromegaly in adults
- Secondary DM is often present
What is the most common cause of death in patients with GH adenomas? Why?
- Cardiac failure
- Cardiomegaly from GH
What is the oropharyngeal finding of GH adenomas?
Macroglossia
What is the hormone produced by the liver in response to GH secretion? What does this do?
- IGF-1
- Mediate the growth of tissues
How do you diagnose a GH adenoma? (2)
- Elevated GH and IGF-1
- Lack of GH suppression by oral glucose
What is the normal response of GH to administration of oral glucose? What would be the response in the case of a GH adenoma?
- Should decrease
- GH adenomas would not respond
What are the two medical treatments for GH adenomas? Why?
- Octreotide since it is a somatostatin analogue, thus it blocks GHRH from acting on the anterior pituitary
- GH receptor antagonist
What percent of the pituitary parenchyma must be lost for s/sx of hypopituitarism to appear?
75%
What type of growth causes hypopituitarism in children? Adults?
- Children = craniopharyngioma
- Adults = pituitary adenoma
What is pituitary apoplexy?
Hemorrhage into the pituitary
What is Sheehan syndrome?
Hypopituitarism d/t pregnancy hypovolemia induced necrosis. This occurs during pregnancy since there is an increased amount of prolactin cells, meaning the pituitary is susceptible to infarction
What are the two classic s/sx of Sheehan syndrome?
No lactation and loss of pubic hair
What is primary empty sella syndrome?
Invasion of the arachnoid mater into the sella turcica destroys the pituitary
What is secondary empty sella syndrome?
Trauma kills pituitary
What are the two hormones released by the posterior pituitary?
- ADH (vasopressin)
- Oxytocin
What are the six hormones released by the anterior pituitary?
- Prolactin
- GH
- FSH/LH
- ACTH
- TSH
What is the role of oxytocin?
Induces milk release and uterine contractions during birthing process
What is the cause of central diabetes insipidus?
ADH deficiency d/t hypothalamic or posterior pituitary pathology
What are the s/sx of diabetes insipidus?
Polyuria and polydipsia
What are the electrolyte disturbances that can occur with diabetes insipidus?
Hypernatremia and high serum osmolality
What are the urinary findings of diabetes insipidus?
Low urine osmolality and specific gravity
How do you diagnose diabetes insipidus?
Water deprivation fails to increase urine osmolality
What is the MOA of desmopressin?
ADH analogue
What is the cause of nephrogenic diabetes insipidus?
Impaired renal response to ADH d/t inherited mutation or drugs
What is the major difference between nephrogenic and neurogenic diabetes insipidus?
Similar, but there is no response to desmopressin in nephrogenic diabetes insipidus
What are the two classic drugs that can cause nephrogenic diabetes insipidus?
Li
Demeclocycline
What is SIADH?
Too much ADH causes too concentrated urine to be produced
What are the electrolyte disturbances that can occur with SIADH?
Hyponatremia and low serum osmolality
What are the s/sx of SIADH?
Highly concentrated urine + mental status changes and szs
What is the classic ectopic cause of SIADH?
Small cell carcinoma of the lung
What are the drugs that can cause SIADH?
Cyclophosphamide
What sort of infection can cause SIADH?
Pulmonary infection
What sort of trauma can cause SIADH?
CNS trauma
What are the two treatments for SIADH?
——
- Free water restriction
- Demeclocycline
What is a thyroglossal duct cyst?
Cystic dilation of the thyroglossal duct remnant that presents as an anterior neck mass
How does the thyroid develop?
Starts at the base of the tongue, and moves down the thyroglossal duct toward the anterior face
What is a lingual thyroid?
Persistence of thyroid tissue at the base of the tongue, that presents as a base of tongue mass
How does thyroid hormone increase BMR?
Increases the synthesis of Na/K ATPase
How does thyroid hormone increase SNS activity?
Increases beta adrenergic receptors
What is the classic arrhythmia that can occur with hyperthyroidism?
A-fib
What are the GI findings of hyperthyroidism?
Diarrhea with malabsorption
What are the uterine gyn findings of hyperthyroidism?
Oligomenorrhea
What happens to the bones with hyperthyroidism?
Bone resorption with hypercalcemia
What happens to muscle mass with hyperthyroidism?
Decreased
What are the lipid and carb abnormalities that can occur with hyperthyroidism? Why?
- Hypercholesterolemia
- Hyperglycemia
-Increased gluconeogenesis and glycogenolysis
What is the most common cause of hyperthyroidism?
Grave’s disease
What is the type of antibody that mediates the effects of Grave’s disease?
IgG
In whom does Grave’s disease usually occur?
Women of childbearing age
What is Grave’s disease?
Autoimmune production of IgG for TSH receptor
What is the cause of the goiter that can occur with Grave’s disease?
TSH receptor stimulation
What causes the exophthalmos and pretibial myxedema in Grave’s disease?
Fibroblasts behind the eye and in front of the tibia have TSH receptors, and will secrete glycosaminoglycans
What happens to the colloid in Grave’s disease?
scalloping (colloid pulls away from the epithelium)
What are the T4 and TSH levels like in Grave’s disease?
- Increased total and free T4
- Decreased TSH
What happens to cholesterol levels with Grave’s disease? Serum glucose?
- Cholesterol decreased
- Glucose increased
What are the 3 treatments for Grave’s disease?
- Beta blockers to block effect on the SNS
- Thioamide to block peroxidase
- Radioiodine ablation
What is the building block for thyroglobulin?
Tyrosine
What form of I is brought into the cell, and what is the form of I that attached to thyroglobulin?
- Iodide (I-) goes into cell
- Iodine attaches to thyroglobulin
What is the reasoning behind using thioamide (an inhibitor of myeloperoxidase) to treat hyperthyroidism?
Inhibits the coupling of I to thyroglobulin
What is thyroid storm?
Elevated catecholamines and massive hormones excess
What are the s/sx of thyroid storm?
- Arrhythmia
- Hyperthermia
- Vomiting
What is the treatment for thyroid storm? (3)
- PTU
- Beta blockers
- Steroids
What is the MOA and use of PTU?
- Inhibits peroxidase coupling of iodine to thyroglobulin, and prevents the conversion of T4 to T3
- Treats thyroid storm
What causes multinodular goiter?
Relative iodine deficiency
What are the consequences of having a multinodular goiter (hypo, hyperthyroid, or euthyroid)?
Euthyroid (normally functioning thyroid)
What is the toxic goiter that can develop from a multinodular goiter?
TSH-independent regions of the thyroid will secrete T3/T4 without stimulation of TSH (badness)
What is cretinism?
Hypothyroidism in neonates and in infants
What are the s/sx of cretinism?
- MR
- Short stature
- Coarse facial features
- Macroglossia
- Umbilical hernia
What are the causes of cretinism? (4)
- Maternal hypothyroidism during early pregnancy
- Thyroid agenesis
- Dyshormonogenetic goiter
- Iodine deficiency
What is the enzyme that is most commonly deficient in Dyshormonogenetic goiter?
Thyroperoxidase
What is myxedema? S/sx?
Hypothyroidism in older children or adults
- myxedema
- Weight gain despite normal appetite
- Muscle weakness
- Cold intolerance
What are the two classic symptoms of hypothyroidism in older children?
Deepening of the voice and macroglossia, both d/t myxedema
What are the gyn findings with hypothyroidism?
Oligomenorrhea
What are the lipid abnormalities that can be caused by hypothyroidism?
Hypercholesterolemia
What are the nutritional causes of hypothyroidism?
Iodine deficiency
What is the autoimmune cause of hypothyroidism?
Hashimoto’s thyroiditis
What is Hashimoto’s thyroiditis?
Autoimmune attack against the thyroid gland, causing destruction
What are the drugs that can cause hypothyroidism?
Li
What is the most common cause of hypothyroidism in the developed world?
Hashimoto’s thyroiditis
What is the HLA gene that is associated with Hashimoto’s thyroiditis?
- HLA-DR5
- Pernicious anemia
Why is there an initial hyperthyroidism in Hashimoto’s thyroiditis?
Destruction of the thyroid tissue causes release of preformed T3/T4
What happens to T4 and TSH levels with Hashimoto’s thyroiditis in the ling term?
- Decreased T4
- Increased TSH
What are the antibodies that are usually present with Hashimoto’s thyroiditis? What is their role in the pathogenesis of Hashimoto’s thyroiditis?
- Antithyroglobulin and antimicrosomal antibodies
- Just markers–do NOT mediate the destruction
What are the classic histological findings of Hashimoto’s thyroiditis?
- Chronic inflammation with germinal centers
- Hurthle cells (basophilic cells)
Patients with Hashimoto’s thyroiditis are at an increased risk of developing what malignancy? Why?
- B cell lymphoma
- Germinal centers develop a marginal zone
Enlarging thyroid gland with Hashimoto’s thyroiditis is suspicious for what?
B cell lymphoma
What is subacute (de Quervain) granulomatous thyroiditis?
Granulomatous thyroiditis that follows a viral infection
What are the presenting s/sx of subacute (de Quervain) granulomatous thyroiditis?
Tender thyroid with transient hyperthyroidism
What is the prognosis for subacute (deQuervain) granulomatous thyroiditis?
Self-limited; does not progress to hypothyroidism
Tender thyroid = ?
subacute (de Quervain) granulomatous thyroiditis
What is Reidel Fibrosing thyroiditis?
Chronic inflammation with extensive fibrosis of the thyroid
What is the usual presentation of Reidel fibrosing thyroiditis?
Hypothyroidism with a “hard as wood” nontender thyroid gland
What are some common complications of Reidel fibrosing thyroiditis?
Fibrosis extending to local structures (e.g. airway)
What are the top two items in your ddx for a hard, nontender thyroid with hypothyroidism? In whom does each occur?
- Anaplastic carcinoma (old people)
- Riedel Fibrosing thyroiditis (young women)
In whom does Reidel fibrosing thyroiditis usually occur?
Young women
What are thyroid nodules?
Distinct, solitary thyroid nodules that are likely benign
Are thyroid nodules more likely benign or malignant?
Benign
What are the characteristics of thyroid nodules?
distinct, solitary nodules
What is the benefit of a radioactive uptake study when assessing for thyroid issues (what increases uptake and what decreases uptake)?
There is increased Iodine 131 uptake with Grave’s disease or nodular goiter, but decreased in adenomas and carcinomas
What is the way to biopsy thyroid nodules?
Fine needle aspiration (FNA)
Why is FNA used to biopsy the thyroid?
Extensive blood supply to the thyroid will cause it to bleed like nuts if biopsied in the usual fashion
What are the results of radioactive Iodine uptake for adenomas/carcinomas? How about for Grave’s disease or nodular goiters?
- Adenomas/carcinomas = decreased
- Graves/nodular goiter = increased
What is the most common benign growth in the thyroid? What are the characteristics of this?
- Follicular adenomas
- Usually surrounded by a fibrous capsule
True or false: follicular adenomas usually secrete thyroid hormone
False
What is the most common type of carcinoma of the thyroid?
Papillary carcinoma
What are the risk factors for developing papillary carcinoma?
Exposure to ionizing radiation in childhood
What are the two classic histologic findings of papillary carcinoma?
- “Annie-eyed” nuclei (nuclei with a white clearing in the center)
- Nuclear “grooves” (basophilic straight lines in the nucleus)
What are psammoma bodies?
concentric. layed calcification that can be seen in papillary carcinoma
Where does papillary carcinoma usually spread?
Cervical nodes
What is the prognosis for papillary carcinoma?
Excellent
What is follicular carcinoma?
Malignant proliferation of thyroid follicles
What are the characteristics of follicular carcinomas?
Follicles surrounded by a fibrous capsule with invasion through the capsule
What is the major difference between follicular adenomas and follicular carcinomas?
Carcinomas will invade through the fibrous capsule
How do you differentiate between follicular adenoma and follicular carcinoma?
Need to examine the entire follicle to ensure that the tumor does not invade the capsule
Can FNA make the distinction between follicular adenoma and follicular carcinoma? Why or why not?
No, because the only difference between the two is invasion of the fibrous capsule
What is the primary means through which follicular carcinoma metastasizes?
Hematogenously
What are the four carcinomas that spread hematogenously?
- Renal carcinoma
- Hepatocellular CA
- Follicular CA
- Choriocarcinoma
What is medullary carcinoma?
Malignant proliferation of parafollicular C cells
What endocrine disorder is produced form medullary carcinoma?
High levels of calcitonin leads to hypocalcemia
Where does the calcitonin deposit with medullary carcinoma? What does it deposit as?
Within tumor as amyloid
What is the classic histological finding of medullary carcinoma?
Follicles within an amyloid stroma
Malignant cells within an amyloid stroma = ?
Medullary carcinoma
What are the causes of familial thyroid carcinoma?
MEN2A and MEN2B
What are the malignancies found in MEN2A?
- Medullary carcinoma of the thyroid
- pheochromocytoma
- Parathyroid adenomas
What are the malignancies found in MEN2B?
- Medullary carcinoma of the thyroid
- pheochromocytoma
- ganglioneuromas of the oral mucosa
What is the genetic cause of MEN2A and MEN2B?
Mutations in the RET oncogene
What is warranted if the RET mutation is found?
Prophylactic thyroidectomy
What is anaplastic carcinoma of the thyroid?
Undifferentiated tumor of the thyroid
In whom is anaplastic carcinoma of the thyroid usually seen?
Elderly
What is the prognosis for anaplastic carcinoma of the thyroid?
Poor
What are the sequelae of anaplastic carcinoma of the thyroid?
Invasion of local structures leading to dysphagia and/or respiratory compromise
