Exam 1-Endocrine Flashcards
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What are the three types of cell signaling?
paracrine, autocrine and endocrine
What are the three general disruptions of the endocrine system?
impaired hormone release/synthesis, abnormal reactions between hormones and target tissue, and abnormal response of target tissue
What can mass lesions cause?
under or overproduction of hormones or be nonfunctional
What are the lobs of the pituitary gland?
anterior lobe(adenohypophysis)-80% and posterior lobe(neurohypophysis)-20% of gland
What three cell types make up the anterior pituitary?
basophils, acidohpils and chromophobes (call can secrete each hormone)
What are the 6 major cell types of the anterior pituitary and what do they secrete?
somatotrophs-GH mammosomatotrophs- GH and prolactin(PRL) lactotrophs- PRL corticotrophs- ACTH, POMC, MSH thyrotrophs- TSH gonadtrophs- LH, FSH
determined by transcription factors
What is produced in the posterior pituitary?
ADH(VPN) and oxytocin
What is involved with hyperpituitarism?
excess trophic hormones, from adenomas, hyperplasia and carcinomas of the anterior pituitary or by from non pituitary tumors or hypothalamic disorders
What is involved with hypopituitarism?
deficiency in trophic hormones from destructive processes like ischemia, surgery or radiation, inflammation and nonfunctional pituitary adenomas
What is involved with local mass effect?
radiologic abnormalities in sella turcica, including expansion, bony erosion and disruption of the diaphragma sella, can compress optic chiasm(bitemporal hemianopisa), increased ICP or hemorrhage into the adenoma, pituitary apoplexy, emergency if acute
What is the most common cause of hyperpituitarism? and other causes?
anterior lobe adenoma-secrete 2 hormones: most common secretions are GH and PRL, but others can be plurihormonal
less common: pituitary carcinoma and hypothalamic disorders
the larger ones can cause mass effect thus causing hypopituitarism through ischemia
What are the demographics for pituitary adenomas?
35-60yo adults, non-functioning adenomas come to light later than functioning due to lack of endocrine response
What is the sizing of pituitary adenomas?
less than 1 cm = microadenoma
1-4cm = macroadenoma
over 4cm = giant adenoma
What genetics abnormalities are associated with pituitary adenomas?
G-protein mutations, GNAS mutation found in 40% of somatatroph adenomas but rarely in corticotroph adenomas, GNAS inhibits GTPase activity thus GDP cannot bind and inhibit the alpha subunit
Which pituitary adenoma is most common?
lactotroph adenoma in 30% of cases with hyperfunctioning pituitary, can have substantial mass affect
What is the morphology of prolactinomas?
chromophobic sparsely granulated (most common) due to inclusions of PIT-1 near the nuclei only, or acidophilic densely granulated (rare) where the cytoplasm is overwhelmed by the inclusions,
these adenomas can undergo calcification and give psamomma bodies throughout the entire mass leaving a “pituitary stone”, even microadenomas can cause hyperprolactinemia, level correlates with size
What is the presentation of lactotroph adenomas? More specifically between M/F?
more readily Dx in women than men due to amenorrhea mostly between 20-40yo, tumor is usually larger in males due to this late finding,
women show amennorhea, galactorrhea, diminshied libido, infertility and amss effect, Men present with mainly mass effect Sx and also decreased sperm count and libido
What can cause hyperprolactinemia without an adenoma?
pregnancy, lactation/nipple stimulation, stress, loss of dopamine-> lactotroph hyperplasia via stroke, trauma or drugs, masses-decrease dopamine release, renal failure- decreased PRL clearance and hypothyroidism-TSH can stimulate PRL
What is the treatment for lactotroph adenomas?
surgery or dopamine agonists- bromocriptine
What is the second most common pituitary adenoma?
somatotroph adenoma, secretes GH
What are the two major findings in somatatroph adenomas?
gigantism in children and acromegaly in adults
What are the morphological findings in somatotroph adenomas?
densely granulated acidophilc cells and sparsely granulated chromophobe cells which have GH inclusions similar to lactotroph adenomas; while there is also a bihormonal mammosomatotroph variant which secrets GH and PRL and typipcally are densely granulated but rare
What is the presentation of gigantism and acromegaly?
gigantism is found when IGF-1 levels are high in children before epiphyseal plates are fused and are typically very tall people, while the findings of both can overlap if the levels stay high after fusion, acrogmegaly shows up as large jaws, hands and noses with coarse facial features, as well as shortened lifespans and CV disease leading to death
How are GH excess pituitary tumors diagnosed?
IGF-1 levels since this is the stable byproduct of GH from the liver, followed by oral glucose tolerance test if elevated which should decrease GH in the blood under normal circumstances
How is the somatotroph tumor treated?
surgery or somatostatin analogs which inhibit GH production, this can casue all Sx to resolve
Which adenoma causes hypercortisolism and why?
caused by corticotroph adenomas secreting excess ACTH thus releasing cortisol
What morphology is seen in corticotroph adenomas?
basophilic densely granulated and chromophobe sparsely granulated tumors, both PAS positive due to POMC the ACTH and beta-endorphin precursor
What is Cushing disease versus the syndrome?
syndrome is from high cortisol levels while the disease is from increased levels of ACTH causing increased cortisol
How is Nelson syndrome caused and what is involved?
large desructive pituitary tumors develop after surgical removal of adrenals to treat Cushing syndrome leads to loss of inhibition of pituitary by corticosteroids and thus increased ACTH or precursor POMC production leading to hyperpigmentation
What is the most common cause of Cushing syndrome?
Iatrogenic due to corticosteroid administration
How are corticotroph adenomas differentiated from ACTH-secreting tumors?
the adenomas maintain some ability to be supressed by high dose corticosteroids(dexamethasone) or elevated response to CRH administration
How can corticotroph adenomas treated?
surgery, bromocriptin or somatostatin analogs, these tumors have some receptors for the above
What is seen in gonadotroph adenomas?
very minimal function and do not cause symptoms therefore are “null cell” or “silent” tumors
How do nonfunctioning adenomas typically present?
mass effect findings
What are thyrotroph adenomas?
very rare and are a cause of hyperthyroidism
What genetic findings are connected to specific pituitary adenomas?
GNAS-somatotroph tumors
USP8- corticotrop tumors(EGFR upregulation)
AIP or FIPA- pituitary adenoma predisposition(PAP)- typically somatotroph adenoms and are familial
Which tumors are well circumscribed?
adenomas, but can erode bone and bleed
Which tumors are poorly cirumscribed?
aggressive adenomas, can invade brain and are more likely with larger adenomas
What are characteristics of pituitary carcinoma?
rare and can metastasize or spread into brain
Define hypopituitarism.
decreased secretion of pituitary hormones as result of hypothalamic or pituitary disease, occurs with 75% loss of gland
List the most common causes of hypopituitarism. (7)
tumors/mass/cysts TBI/hemorrhage surgery/radiation/apoplexy ischemic necrosis/Sheehan syndrome inlammatory disorders genetic defects
What is Sheehan syndrome?
during pergnancy the pituitary gland swells and can get so large that it infarcts, due to lack of blood flow and hemorrhage during birth, and cannot maintain homeostasis any longer, typically occurs at labor
What is Rathke’s cleft cyst?
lined by ciliated cuboidal cells can accumulate fluid causing mass effect on pituitary gland
What is empty sella syndrome?
anything casuing destruction of pituitary gland,
primary is caused by compression with CSF
secondary is caused by infarction of the gland within the sella or with surgical removal
What can be seen in children with hypopituitarism?
pituitary dwarfism
What two groups make up hypothalamic supraselar tumors?
craniopharyngioma and gliomas
What are characteristics and demographics of craniopharyngiomas?
peak in children 5-15yo, with growth retardation, and adults 65yo+, usually with visual disturbances and HA, involved with WNT and B-catenin signaling
Which morpholical findings are in each age range?
kids have adamantinomatous type, while adults have the papillary type, overall arise from Rathke’s pouch, with squamous epithleium, wet keratin and contain calcified cysts
What is the survival of craniopharyngiomas?
less than 5cm is excellent as are the others although larger tumors can cause other issues
What are the major posterior pituitary disorders?
Diabetes inspidus and SIADH
What is seen in DI?
too little ADH, can be central, or not producing enoguh or nephrogenic when the kindey cannot respond to it,
patient has dilute excessive urine, increased serum osmolality, hypernatremia, pulyuria, polydipsia
How do you distinguish central and nephrogenic DI?
give DDAVP, does urin concentration increase? yes-central, no-nephrogenic
What are characteristics of SIADH?
hyponatremia, concentrated urine, low serum osmolality, hypernatriuria, mental status changes, weakness, SZ, cerebral edema but no peripheral
What are causes of SIADH?
SCC of the lung and other CA
TBI/subarachnoid hemorrhage
Drugs-SSRIs
What are the different types of hyperparathyroidism?
primary-caused by end organ dysfunction
secondary caused by another issue somehwere in the body, hypocalcemia chronically
tertiary is continued PTH elevation after prolonged hypocalcemia is corrected
What is the most common cause of primary hyperparathyroidism?
sporadic adenoma(85-95%)
hyperplasia(5-10%)
carcinoma(1%)
What are the demographics or primary hyperparathyroidism?
adults >50yo, 4:1 in women to men
What genetic factors play a role in development of sporadic parathyroid adenomas?
cyclin D1 overexpression linked to PTH gene
MEN1 mutations result in 20-30% of sporadic adenomas
What genetic dispostions are associated with familial parathyroid adenomas?
MEN1 and MEN2 caused y mutation in MEN1 and RET genes respectively
as well as familial hypocalciuric hypercalcemia(AD, loss-of-function in CASR)
What imaging is useful for seeing parathyroid adenomas?
technetium scan, fuse with CT for localization
What is the morphology of parathyroid adenomas?
solitary, benign chief or oxyphil cells, surrounded by rim of normal parathyroid tissue(has adipocytes), soft tan, reddish-brown, other glands are shrunken due to feedback inhibition, not true in hyperplasia
Are sporadic or familial parathyroid adenomas more common?
sporadic but still due to MEN1 gene just not familial MEN1
What are characteristics of parathyroid hyperplasia?
multiple glands, most likely due to MEN syndrome, no sporadic, secondary form is most common, no normal parathyroid tissue at rim, no adipocytes
Why can PTH be monitored in surgery?
due to short T1/2, so a new baseline can be determined, if it doesn’t decrease after surgery think carcinoma
How can parathyroid carcinoma be diagnosed?
metastasis, invasion of adjacent tissues, vascular invasion, PTH doesn’t decrease after surgery
What are Sx of primary hyperparathyroidism?
osteoporosis, osteitis fribosis cystica nephrolithiasis constipation, gallstones depression, lethargy, SZ weakness, fatigue heart valve calcifications
What are characteristics of osteitis fibrosis cytica?
aka von Recklinghausen’s disease of bone
brown tumor, destroys bone with osteoclast resorption, causes small fractures, hemorrhage and reactive tissue, can look like metastasis, usually asymptomatic due to routine lab identification
Most common cause of asymptomatic hypercalcemia?
primary hyperparathyroidism
Most common cause of symptomatic hypercalcemia?
hypercalcemia of malignancy
What causes secondary hyperparathyroidism?
chronic hypocalcemia, leading to compensatory overactivity of the gland
What bone disorder can secondary hyperparathyroidism lead to? and what does it show?
renal osteodystrophy, dissecting osteitis leading to rugger jersey sign
What vascular disease can secondary hyperparathyroidism lead to?
calciphylaxis, extensive calcification and occlusion of vessels with ischemia, patients die from infection
What is the mechanism of hypercalcemia of malignancy?
humoral hypercalcemia of malignancy is caused by PTHrP from squamous cell CA or vitamin-D mediated from lymphomas
local osteolytic hypercalcemia
caused from bone breakdown by osteoclasts and calcium release secondary to breast CA and myeloma
What are the causes of acquired hypoparathyroidism?
iatrogenic- surgery and autoimmune-due to ASP1 and AIRE mutations, presents in childhood with candidiasis and adrenal insufficiency
What are causes of congenital hypoparathyroidism?
DiGeorge syndrome, CASR mutations, familial isolated hypoparathyroidism
What causes DiGeorge syndrome?
failure of 3rd and 4th pharyngeal pouches to develop, parathyroid glands do not develop, 22q11
What causes familial hypocalcemic hypocalciuria?
CASR mutation, overactive calcium sensor
What causes familial isolated hypoparathyroidism?
cannot convert precursos PTH to functional PTH, GCM2 gene mutation, helps parathyroid develop
What are the hallmark findings in hypocalcemia? Other findings?
tetany, determined with chvostek’s sign and trousseau’s sign, others include mental status changes, intracranial manifestations(ICP increase, parkinsonian Sx), ocular disease, CV issues, dental abnormalities
What are characteristics of pseudohypoparathyroidism?
normal or elevated PTH, hypocalcemia and hyperphosphatemia, PTH resistance, GPCR defect, affects TSH, LH/FSH pathways as well
What cells make up the thyroid gland follicles?
cuboidal to low columnar cells
What is another name for TSH and how does it stain?
thyrotropin stains PAS-positive
What occurs when TSH binds thyroid cells?
GPCR activation causing increased cAMP causing production of T4(thyroxine) and less T3(triiodothyroxine) from thyroglobulin
What is the essential action of thyroid on the body?
increase basal metabolic rate (HR, metabolism, glucose usage, growth) also lowers TSH released for negative feedback
What is the simple description of hyperthyroidism?
increased free T3 and T4 in the blood causing hypermetabolic state(also called thyrotoxicosis)
What are the most common causes of thyrotoxicosis?
diffuse hyperplasia(Graves disease) hyperfunctioning multinodular goiter hyperfunctioning thyroid adenoma
What occurs during thyroid storm?
sudden severe onset of thyrotoxic manifestations, including the following:
fever, tachycardia, CHF
diarrhea, jaundice
precipitated by pregnancy/postpartum, hemithyroidectomy, amiodarone
make up the burch wartofsky score
What is the treatment for thyroid storm?
beta blockers, NSAIDs, underlying disease treatment such as: high-dose iodide(Wolff-Chaikoff effect), thionamide, radioiodine ablation, surgery
What is the most common etiology of hyperthyroidism?
Gravs disease
What is the classic triad of Graves disease?
hyperthyroidism with hypertrophy
infiltrative ophthalmopathy
pretibial myxedema
What changes in the thyroid histology with active secretion?
intracytoplasmic droplets appear, containing colloid ready to be released
What causes the orbital changes in Graves disease or hyperthyoidism in general?
increased stimulation of the superior tarsal muscle leading to hypertrophy of it and the EOMs causing the eye to bulge, there is also a build-up up adipose tissue in the orbit and myofibroblast differentiation caused by lymphocyte invasion, fibroblasts have TSH receptors(true orbital ophthalmopathy only occurs in Graves disease)
What happens to the nervous system in hyperthyroidism?
overactivity of the SNS produces tremor, amotional lability, anxiety, insomnia and inability to concentrate
also causes proximal muscle weakness and decreased muscle mass(thyroid myopathy)
What CV effects are seen in hyperthyroidism?
increased CO and contractility requiring increased oxygen, tachycardia, palpitations, cardiomegaly, CHF in older patients with existing disease, as well as reversible LV dysfunction with low output(thyrotoxic cardiomyopathy)
What are the effects of hyperthyroidism on bones?
stimulates bone resorption, reducing trabecular bone volume
What is apathetic hyperthyroidism?
older individuals with multiple comorbidities where the increased thyroid comes to attention via labs because the symptoms are overshadowed by the other diseases
What is pathophysiology behind Graves disease?
autoimmune mediated disease, with 90% showing TSI(Ig), very specific to graves.
What is the underlying morphology in Graves disease?
diffuse hypertophy and hyperplasia of the thyroid follicular epithelial cells, no fibrovascular core like in carcinomas, mostly T cell infiltrates, some B cells and plasma cells, skin can show dermopathy, there are papilla projecting into the colloid space
What is the basic definition of hypothyroidism?
structural or functional derangement that interferes with thyroid production
What is the demographic for hypothyroidism?
women 10x more than men, increases with age, and pre-existing or FMH of autoimmune disease
What is congenital hypothyroidism?
cretinism, depends on the extent the mother was without iodine, typically seen in children due to endemic areas of iodide shortage, presents with severe mental and growth retardation, coarse facial features and umbilical hernias, also caused by genetic alterations
What are characteristics of myxedema?
hypothyroidism in older children and adults, similar to cretinism in children, mental/physical sluggishness(slowing), weight gain, cold intolerance, lower CO, hypercholesterolemia, constipation,
What is the most sensitive screening tool for myxedema?
serum TSH levels, high if primary hypothyroidism, low if secondary
What is the underlying cause of Hashimoto thyroiditis?
autoimmune response to thyroid tissue causing its destruction and gradual failurem specifically against T4 and TPO
What is the most common cause of hypothyroidism in iodine-sufficient areas?
hashimoto thyroiditis
What are characteristics of Hashimoto thyroditis?
diffuse, painless enlarged thyroid, low thyroid levels(except in Hashitoxicosis), starts as insult, hypertrophy occurs and terminates in exhaustion, or low thyroid levels, middle aged females, higher propensity for autoimmune diseases, increased risk for B cell lymphoma in the thyroid
What is the morphology in Hashimoto thyroiditis?
T cell and plasma cell mediated injury, breakdown in Treg cells or polymorphisms in CTLA-4 and PTPNN22, histology shows mononuclear infiltrates with germinal centers and atrophic follicle cells with eosinophilic exhcange(Hurthle cell metaplasia)