Adrenal Gland Pathology Flashcards
What hormones does the zona glomerulosa secrete ?
mineralocorticoids
aldosterone main one, stimulated by angiotensin 2 and increased by extracellular K+ concentration
increases K+ excretion and Na+ retention at kidneys
What hormones does the zona fasciculata secrete ?
glucocorticoids
mostly cortisol, promoted by stress
effects = induce hyperglycaemia, lipolysis and protein catabolism, suppress inflammation and immune responses, inhibit wound healing
What hormones does the zona reticularis secrete ?
sex hormones
What hormones does the medulla secrete ?
catecholamines, adrenaline and noradrenaline “flight or flight” repsonse
Define adrenal agenesis
absence of adrenal gland at birth may be bilateral or unilateral
bilateral is lethal as electrolyte and fluid imbalances (no mineralocorticoids)
unilateral is clinically normal
How does an adrenal haemorrhage occur ?
blood supply to the adrenal glands is via a sinusoidal plexus that is fragile and susceptible to damage
–> exertional death, abortions, coagulopathies and septicaemia
Define an adrenal infarction
death of adrenal gland tissue due to a lack of blood supply, commonly causes by sepsis.
grossly, wedge-shaped area of necrosis
Define and give the causes of adrenalitis
the adrenal glands have an anti-inflammatory environment, due to the cortisol effect (suppression of cytokine production)
this can only be over-ridden by an infectious or autoimmune cause
Define an adrenal cortical adenoma
benign neoplasm common in old dogs
well defined, encapsulated nodules that compressions and distorts surrounding tissue
functional or non-functional
How do you tell the difference between nodular hyperplasia and an adenoma ?
hyperplasia is multiple, bilateral, not encapsulated, small (<1cm) and does not compress surrounding tissue
Define an adrenal cortical carcinoma
large, poorly defined and efface normal tissue, more common in older dogs and cows
sometimes bilateral
malignant
see vascular invasion, thrombosis and blood in the abdominal cavity
Define Cushing’s disease
hyperadrenocorticism
Name the 4 forms of Hyperadrenocorticism
pituitary-dependent
- pituitary tumour secretes ACTH
- unresponsive to cortisol feedback pathway
- excess ACTH secretion causes hyperstimulation of cortex and bilateral adrenocortical hyperplasia
adrenal-dependent
- adrenal neoplasm secretes excess cortisol independent of ACTH
- excess cortisol suppresses ACTH secretion
- bilateral adrenocortical atrophy with visible mass
iatrogenic
- administration of chronic, high-dose corticosteroids
- exogenous corticosteroids suppress ACTH
- bilateral adrenocortical atrophy
ectopic ACTH secretion
- secretion of ACTH by a non-pituitary neoplasm
- bilateral adrenocortical hyperplasia
CS of hyperadrenocorticism
excess cortisol –> increased protein catabolism, lipolysis, suppressed inflammatory response
“stress” effects –> lose hair, eat more, drink more, increase BW, blood glucose increased, suppressed immune system
muscle catabolism –> abdominal and limb muscle atrophy, “pot-bellied”
PU/PD –> decreased sensitivity to ADH
hyperglycaemia, polyphagia, immunosuppression
Name the skin CS of hyperadrenocorticism
alopecia at pressure points and flanks, often bilaterally symmetrical, can see keratin plugs in follicles at histology
dermal atrophy with catabolism of collagen
hyperpigmentation due to excess ACTH
calcinosis cutis - calcification of degenerate collagen on the skin and other organs
