GP- adrenal glands

what are the 3 types of endocrine disease?

hyperfunction

hypofunction

affection of adjacent tissues

what are the main causes of endocrine hyperfunction?

-functional neoplasia

-regulatory mechanisms fail

-hormone-like substances

-iatrogenic overactivity (drugs)

what are the causes of endocrine hypofunction?

-non-functional neoplasia

-inflammation

-lack of sensitivity of the effector organ

-hormone production/release defects

-congenital anomaly

are congenital anomalies common causes of endocrine hypofunction in dogs and cats?

no

the adrenal cortex is composed of what layers? what hormone does each produce?

glomerulosa: aldosterone (mineralocorticoid)

fasciculata: cortisol (glucocorticoid)

reticularis: glucocorticoids and sexual androgens

aldosterone has a half life of how long?

60-90 min

what is the half life of cortisol?

20min

what are the functions of cortisol in the body?

metabolism:

-↑ glycemia (stim gluconeogenesis, antagonizes its inhibition, and ↓ insulin sensitivity)

-↓ proteins in cells and ↑ plasma proteins

-mobilizes fat from adipose

-↑ oxidation of fatty acids in cells

-anti-inflammatory

-immunosuppressive

-stress response

what is the function of aldosterone in the body?

promotes Na+ reabsorption and K+ excretion → ↑ water reabsorption

aldosterone is produced/secreted more in states of ________

hypotension, hypovolemia, ↑ K+ blood levels

what hormone increases Na+ reabsorption and K+ excretion?

aldosterone

what system in the body stimulates secretion of aldosterone?

the RAAS

in states of hypovolemia or hypotension

what hormone stimulates the adrenal cortex to release cortisol?

ACTH from the hypophysis

when the hypothalamus secretes _________, it stimulates the hypophysis to secrete ACTH, which has what effect on the adrenal cortex?

CRH

stimulates the release of cortisol

what is the role of ACTH?

it is the hormone released from the pituitary to stimulate the release of cortisol

cortisol gives negative feedback to the _______, decreasing release of _______

hypothalamus; CRH

hyperadrenocorticism is also known as....

cushing's syndrome

primary HAC makes up _____% of all HAC cases.

15%

most HAC cases are ______ (primary or secondary)

secondary (85%)

what is primary HAC?

hyperadrenocorticism caused by a functional adrenal tumor. it can be benign (adenoma) or malignant (adenocarcinoma).

it causes the ↑ release of cortisol and therefore the ↓ release of CRH and ACTH (due to negative feedback)

what is the name of the disease caused by a functional tumor on the adrenal gland?

primary hyperadrenocorticism

what causes secondary HAC?

an ACTH producing pituitary tumor

which- primary or secondary HAC is easier to diagnose?

primary, because the tumor is usually big and visible on an ultrasound.

secondary HAC tumors are microadenomas in small animals, so are not visible in an ultrasound. however, in horses they are macroadenomas

how is the size of the adrenal glands in a patient with primary HAC?

this tumor is usually unilateral, so the affected adrenal gland is larger, and the unaffected gland is atrophied.

how is the size of the adrenal glands in a patient with secondary HAC?

both are hyperplastic (larger) due to increased stimulation from the pituitary (secondary HAC is due to a functional tumor on the pituitary)

what is the difference between a functional and non-functional endocrine tumor?

functional- increases the activity of the gland. the patient will have hyperfunction.

nonfunctional- decreases the activity of the gland. the patient will have hypofunction.

how does cortisol affect proteins and glucose?

↑ blood glucose

↑ blood proteins

an animal with a functional ACTH producing tumor on the pituitary has what disease?

secondary hyperadrenocorticism

what is the pathophysiology of secondary hyperadrenocorticism?

a tumor on the pituitary causes the ↑ of ACTH release, which stimulates the adrenal gland, so there is ↑ cortisol.

negative feedback causes a ↓ in CRH

an animal with primary HAC will have ____cortisol, _____CRH, and _______ACTH

↑ cortisol

↓ CRH

↓ ACTH

an animal with secondary HAC will have ____cortisol, _____CRH, and _______ACTH

↑ cortisol

↓ CRH

↑ ACTH

is it easy to diagnose a dog or cat with secondary HAC?

no, because the tumor is a microadenoma, so is not visible with imaging

what is the cause of iatrogenic HAC?

clinical error- chronic excess of exogenous corticosteroids.

the chronic excessive administration of glucocorticoids will cause what disease?

iatrogenic HAC

what is the pathophysiology of iatrogenic HAC?

↑ cortisol (exogenous), sends negative feedback to hypophysis and hypothamalus, causing ↓ ACTH and CRH

which type of HAC has suprarenal (adrenal) bilateral atrophy?

iatrogenic HAC, because the adrenal glands do not work as much due to the excess exogenous cortisol

what are the consequences of ↑ cortisol in the body?

-mobilizes energy from storage

-↑ CV tone

-delays long-term processes (feeding, digestion, growth, reproduction)

-↓ protein synthesis and ↑ protein degradation

-induces fat mobilization

what animals are more likely to have HAC?

-middle to advanced age

-50-60% are female

-primary HAC: large breeds

-secondary HAC: small breeds

-rare in cats

is HAC common in cats?

no, it is rare

but it can be secondary to diabetes mellitus

small breed dogs are more predisposed to _____ HAC (primary/secondary), while large breeds are predisposed to _______HAC

small: secondary

large: primary

what are the common clinical signs of HAC?

-PU/PD

-polyphagia

-pendulous abdomen

-obesity

-diabetes mellitus

-alopecia

-skin fragility and atrophy

-pyoderma

-hyperpigmentation

-comedones

-calcinosis cutis

-wound healing delay and predisposition to infections

-osteoporosis/ osteodistrophy

-muscle weakness

-lethargy

-pulmonary thromboembolism

-reproductive disorders

is it easy to detect HAC from the clinical signs?

yes, the clinical signs are very obvious

what skin problems can HAC cause?

alopecia

comedones

hyperpigmentation

pyoderma

fragility

skin atrophy

calcinosis cutis

seborrhea sicca

wound healing delay

bilateral alopecia is typical of what disease?

hyperadrenocorticism

what is the effect of HAC on the animal's metabolism?

-↓ protein synth

-↑ protein catabolism

-induces fat mobilization

these will result in:

-polyphagia

-pendulous abdomen

-obesity

-diabetes mellitus

a pendulous abdomen is a characteristic of what disease?

hyperadrenocorticism

(bc of muscle weakness, fat accumulation, and hepatomegaly)

how can the cardiorespiratory system be affected with hyperadrenocorticism?

-pulmonary thromboembolism (due to clotting factor alteration and systemic hypertension)

-increased vascular tone → hypertension

what reproductive disorders do we see with hyperadrenocorticism?

alteration of cycles

testicular atrophy

hypoadrenocorticism is commonly known as...

addison's disease

is addison's disease common in pets?

no

which is more common- primary hypoadrenocorticism or secondary hypoadrenocorticism?

primary (95%)

secondary hypoadrenocorticism makes up ____% of the hypoadrenocorticism cases

5

what is the cause of primary hypoadrenocorticism?

destruction of the adrenal cortex:

-immunomediated

-drugs

-infectious disease

-treatment of HAC

an animal with primary hypoadrenocorticism will have:

_____ cortisol

______ aldosterone

_____ ACTH

______ CRH

↓ cortisol

↓ aldosterone

↑ ACTH

↑ CRH

what may cause the destruction of the adrenal cortex? what is this disease called?

hypoadrenocorticism

causes:

immunomediated

drugs

treatment of HAC

infectious disease

secondary hypoadrenocorticism is caused by ______

a non-functional intracranial tumor on the hypothalamus or pituitary gland.

this causes ↓ stim to the adrenal gland and therefore ↓ cortisol

if there is a non-functional tumor on the hypophysis, there will be _____ ACTH, ______CRH, and ________cortisol

↓ ACTH

↑ CRH (neg. feedback)

↓ Cortisol

if there is a non-functional tumor on the hypothalamus, there will be _____ ACTH, ______CRH, and ________cortisol

↓ ACTH

↓ CRH

↓ Cortisol

primary hypoadrenocorticism means there is destruction of the ______

adrenal cortex

a non-functional tumor either on the hypophysis or hypothalamus will cause what endocrine disease?

secondary hypoadrenocorticism

what is the cause of iatrogenic hypoadrenocorticism?

-abrupt suppression of high doses of glucocorticoids

-overdose of trilostane: treatment for HAC

-treatment with spironolactone

overdosage of trilostane can cause what endocrine disease?

iatrogenic hypoadrenocorticism

because it is the drug to treat HAC, so suppresses the cortisol release. too much can cause not enough release

what are the clinical signs of hypoadrenocorticism?

due to K+ and H+ retention:

-hyperkalemia (causes delayed electrical conduction in the heart → cardiac arrest and asystole)

-metabolic acidosis

-vomit/diarrhea

-abdominal pain

-dehydration → renal failure

what breeds are predisposed to hypoadrenocorticism?

great dane

portuguese water dog

poodle

rottweiler

west highland white terrier

what is the effect of hypoadrenocorticism on electrolytes?

↑ H+ and K+ in the blood

treatment with spironolactone can possibly cause what endocrine disease?

iatrogenic hypoadrenocorticism (because it inhibits aldosterone)

if we are administering high doses of glucocorticoids to an animal and then abruptly stop treatment, what endocrine disease can this cause?

hypoadrenocorticism