Endocrine Flashcards
What are the three types of hormones? Which are stored in granules?
- Polypeptides- synthesized and stored in
granules (TRH, ADH, ACTH, TSH, PTH) - Steroid hormones – not stored,
(mineralocorticoids, cotisol, steroids, sex steroids) - Amino acid derivatives – T3, T4, catecholamines
Primary vs. Secondary endocrine dysfuction
Primary: lesion in the organ itself
Secondary: lesion in another organ that affected hormone production/release
Causes for primary hyperfxn and hypofxn?
hyperfxn: neoplastic
hypofxn: immune-destruction, fail to develop, fail to product hormones d/t genetic defect
Most common cause for secondary hyperfxn & hypofxn?
hyperfxn: active tumor (secretes hormone) not in main endocrine organ (aka in pituitary)
hypofxn: inactive tumor
What are the two types of tumors associated with Humoral hypercalcemia of malignancy (paraneoplastic syndrome)? What do they produce?
T-cell lymphoma & apocrine anal sac adenocarcinoma
PTHrP
List the mechanisms of endocrine dysfunction?
- Primary hypo/hyperfxn
- Secondary hypo/hyperfxn
- hypersecretion of hormones by non-endocrine tumors
- failure of target cell response
- failure of fetal endocrine fxn
- abnormal degradation of hormones
When pheonobarb is administered long term, what can be the result for degradation of a specific hormone?
increases liver enzymes that degrade T4
What liver condition leads to decreased degradation of estrogen by the liver and feminization of hyperestrogenism?
cirrhosis
What embryological strucuture if it persists will result in the lack of a pituitary gland?
Rathke’s pouch
What are the two divisions of the pituitary gland?
neurohypophysis
adenohypophysis
What hormones does the neurohypophysis produce?
oxytocin and ADH
What are the three parts of the adenohypophysis and what hormones do they produce?
pars distalis- ACTH, TSH, FSH, LH,
LTH, GH
pars intermedia (posterior lobe)- ACTH in the dog
pars tuberalis- capillaries
A german shepherd presents with with the following on necropsy. DDX?
Common breeds?
Pituitary Cyst – results in Juvenile
Panhypopituitarism (Pituitary Dwarfism)
A brachycephalic breed/GSH dog presents to you with slow growth, retention of puppy coat (lack of guard hairs), bilateral symmetrical alopecia, delayed permanent dentition, secondary
hypothyroidism and hypoadrenocorticism.
DDX?
Juvenile Panhypopituitarism
A boston/boxer/dachshund presents with muscle atrophy, pot belly, hepatomegaly, redistribution of fat on dorsal midline of neck.
DDX?
hyperadrenocorticism (Cushing’s)
What parts of the adenohypophysis could a corticotroph (ACTH-secreting) adenoma be located?
pars distalis & pars intermedia
Corticotroph (ACTH-secreting) adenoma:
T/F Severity of disease not related to tumor size.
What signs could be seen with a large tumor?
True
CNS, DI (PU/PD), blindness
A boxer with signs of Cushing’s. Neoplasia type?
Pituitary adenoma
An old mare presents with PU/PD, laminitis,
increased appetite, muscle weakness,
somnolence (strong desire for sleep), intermittent pyrexia, generalized hyperhidrosis (excessive sweating), hyperglycemia,
glucosuria, *hypetrichosis (hirsutism) due to
failure of seasonal shedding.
DDX?
PPID
likely a melanotroph adenoma in PI
A dog presents with thick skin, coarse bone, gingival hyperplasia, macroglossia (large tongue), large viscera, increase connective tissue.
DDX?
acromegaly d/t somatotroph adenoma producing excess GH
A cats presents with prognathia inferior and diabetes mellitus.
DDX?
acromegaly d/t somatotroph adenoma producing GH
A dog presents with PU/PD, hypo-osmotic urine- cannot concentrate (associated with ADH hormone production).
DDX? What structure is targeted in the brain?
hypophyseal form: inadequare ADH
(destruction of pars nervosa or infundibular stalk or hypothalamus from cyst, tumor, trauma, inflammation)
nephrogenic form (target cell defect)
What is the normal cortex:medulla ratio?
1:1 or 2:1
Describe four causes for Cushing’s?
- Functional ACTH producing pituitary adenoma
- Functional adrenocortical adenoma or carcinoma
- Idiopathic hyperplasia of adrenal cortex
- Iatrogenic from chronic corticosteroid administration
What are the two types of adrenal cortical hyperplasia?
Which one is often associated with a pituitary adenoma?
Which is depicted?
How can hyperplasia be differentiated from an adenoma?
nodular- in the picture, older animals
diffuse- pituitary adenoma
adenoma in adrenal gland is usually UNILATERAL
hyperplastic nodules- BILATERAL
Bilateral adrenal gland hyperplasia
A single, unilateral, well-demarcated mass in the adrenal cortex with contralateral adrenal gland atrophy.
adrenal cortical adenoma
Is an older dog presents with a mass in the adrenal cortex bilaterally, DDX?
nodular hyperplasia
cortical carcinoma (very invasive and met- check thoracic rads)
A dog presents with hepatomegaly, delayed wound healing, frequent infections, bilateral symmetric alopecia with calcinosis cutis, increased appetite, pendulous belly, and CNS signs, & PU/PD.
DDX?
Cushing’s
Pituitary adenoma (CNS signs, and ADH effects)
Calcinosis cutis is a results of ….. calcification where Ca salts precipitate on degenerating collagen.
dystrophic
Calcinosis cutis
symptom of Hyperadrenocorticism
This histo slide shows what?
collagen degeneration and deposition of Ca-salts (aka calcinosis cutis)
Associated with Cushings
Why is hepatomegaly seen with Cushing’s Dz?
causes accumulation of glycogen in the liver
Labwork from a dog shows:
- Neutrophilia without a left shift
- Lymphopenia, eosinopenia, monocytosis
- Elevated glucose & ALP
- Low urine specific gravity
DDX?
Cushing’s
A cat presents for skin that is sloughing off.
DDX?
Cushing’s
(not as common in cats, liver lesions not usually present, no calcinosis cutis )
Adrenal gland is mainly medulla ( cortex:medulla = 1:4). Often seen with what condition?
Addison’s aka hypoadrenocorticism (Def GC ZF/ZR; sometime mineralcorticoids ZG)
Mechanisms for hypoadrenocorticism?
- idiopathic
- immune-mediated destruction
- long term steroid tx leads to adrenal cortex atrophy
- pituitary lesions affect ACTH zones in adrenal gland
A dog presents with weight loss, impaired stress tolerance, non-specific gastroenteritis, bradycardia/hypotensive shock.
You run labwork and get the following: hyperkalemia & hypochloremia/hyponatremia. Na:K ratio is 23:1.
DDX?
What do you see on the thoracic rad and why?
Addison’s (hypoadrenocorticism)
microcardia; d/t hypovolemia from loss of NaCl
The picture is of the adrenal gland. If given choice between cortex or medulla tumor, which is more likely and why?
medulla tumor d/t red color
(tumors of cortex are more tan in color)
most common neoplasm in the adrenal medulla?
pheochromocytoma
small- no met
large- invasive and met
Where are the most common locations for a pheochromocytoma to metastasize to?
- liver
- regional lymph nodes
- spleen
- lungs
A patient presenting with tachycardia, edema, and cardiac hypertrophy may have excess production of which hormones from what tumor type?
catecholamines
pheochromocytoma
Difference between the two pheochromocytomas?
top= hemorrhage
bottom: breakdown of blood produces darker color
What occurred and what are the potential causes?
adrenal hemorrhage
- birth trauma in newborns
- exhaustion phase stress response
- toxemia (intestinal torsion horses)
- septicemia (injure endothelial lining of adrenal sinusoids)
What two cell types are in the thyroid gland and what hormones do they produce? Which is controlled by the pituitary via TSH?
follicular: T3 & T4 (under control by TSH)
parafollicular cells: calcitonin (lowers blood-Ca)
Where is a common location for extopic thyroid tissue? What tumor is a DDX for a heart base tumor?
ascending aorta at base of heart
thyroid carcinoma
A dog presents with cysts or sinus tracts along ventral midline of the neck that produce watery/mucoid secretions. Formed fistulous tracts to the skin when it ruptured.
DDX?
Thyroglossal duct cysts
nonneoplastic enlargement of thyroid gland as
a result of follicular cell hyperplasia
goiter
What is the difference between diffuse and multinodular goiter?
Diffuse: TSH induced response to hypothyroidism
Multinodular: old cats, autonomous hyperthyroidism (independent of TSH)
Name 4 causes of goiter?
- Iodine deficiency
- Iodine excess (disrupts T3/T4 release)
- Goitrogens
- Defects in the synthesis of thyroid hormones (congenital dyshormonogenetic goiter)
What is a major cause of diffuse goiter?
iodine deficiency especially during the fetal & neonatal period
In which geographic areas, is iodine deficiency common?
Pacific Northwest and the Great Lake regions
A fetus presents with diffusely enlarged & reddened thyroid glands. DDX?
iodine deficiency
DDX?
Goiter- iodine deficiency
Describe the histology changes in this slide?
DDX?
Histo –
- increased vascularity (red),
- follicles irregularly enlarged,
- decreased luminal diameter,
- follicular cell hypertrophy (columnar),
- colloid paler
Iodine Deficiency- goiter
A fetus presents with myxedema in the dermis and less hair. What is myxedema and DDX?
myxedema- change in the dermis with edema and GAG
What is the machnism by which excess iodine can act as a goitrogen?
by interfering with proteolysis of colloidal thyroglobulin thereby preventing hormone secretion
Under what circumstance would the follicular cells be atrophied but the thyroid gland be large?
The involution stage after repletion of dietary
iodine in cases of hyperplastic goiter.
Thyroid gland remains enlarged, but follicular
cells have undergone atrophy because of
decrease TSH
DDX? Primary or Secondary endocrine dysfxn?
What resulting condition common in dogs will result?
idiopathic follicular atrophy (lymphocytic thyroiditis?)
Primary
Hypothyroidism
DDX?
What cell infiltrates the thyroid gland?
Lymphoplasmacytic Thyroiditis
thyroid reactive T-lymphocytes
Discrete tan/brown nodules on thyroid.
Neoplasm type?
Functional?
most common species?
follicular adenoma
yes, fxn (hyperthyroidism)
cats
A very invasive tumor derives from ectopic thyroid tissue is found in a dog.
Likely tumor type?
It has likely met to which organ?
Is it fxn or non-fxn?
follicular carcinoma
lungs
non-fxn
Bulls fed a high Ca diet are prone to develop …?
What other neoplasm is common to see?
thyroid C-cell hyperplasia & neoplasm
bilateral pheochromocytoma
What is the most common incidental thyroid tumor of equines?
c-cell adenoma
What C-cell neoplasm is found in dogs/bulls?
Met to where?
C-cell carcinoma
regional l.n. & lungs
A bull presents with a bulge in the neck region and increase vertebral bone density.
DDx?
C-cell hyperplasia/carcinoma
What cells produce PTH in the parathyroid gland?
What effect does PTH have on Ca & P levels?
chief cells
increase blood Ca; decrease blood P
A miniture schauzer presents with hypocalcemia and hyprphosphatemia.
DDX?
hypoparathyroidism d/t chief cell atrophy
What are the three causes of primary hyperPTH?
- PTH chief cell adenoma- dogs, small
- PTH chief cell carcinoma- large, invasive
- Idiopathic, multinodular hyperplasia of chief cells-dogs
What are the two types of secondary hyperPTH?
Is secondary or primary hyperPTH more common?
renal
nutritional
secondary more common
How can you differ primary from secondary hyperPTH based on gross changes?
primary- tumor, could be unilateral
secondary- diffuse, bilateral
Causes for nutritional hyperPTH?
- high P
- low Ca
- low Vit. D
DDX?
nutritional hyperPTH (Bran/Big head Disease)
High P in bran feeds-
Increase PTH pulls calcium out of bone-bony
remodeling with fibrous connective tissue aka Fibrous osteodystrophy
Metabolic bone disease in reptiles is a result of what?
nutritional hyperPTH
The fibrous osteodystrophy (rubber jaw) observed in this puppy is a result of what?
Why did this condition occur?
renal secondary hyperPTH d/t primary renal dysplasia
Increase PTH response to hyperphosphatemia, hypocalcemia, or low blood calcitriol (helps absorb Ca from intestines)
