Dz of the Adrenals Flashcards
Adrenal gland cortex
Glomerulosa: aldosterone
Fasciculata: cortisol, sex hormones
Reticularis: androgen, some cortisol
Function of the adrenal cortex
Glucocorticoid regulation (neg feedback regulation CRH and ACTH)
Aldosterone regulation (osmoreceptors, RAAS, K+ levels)
Medulla
Catecholamines
Primary hypoadrenocorticism
Immune-mediated destruction of adrenal cortices
Usually bilateral
Drug induced hypoadrenocorticism
Mitotane and trilostane
Other causes of hypoadrenocorticism
Iatrogenic
Thromboembolism/ loss of blood supply
Infiltrative neoplasia
Amyloidosis
Signalment of hypoadrenocorticism
Young to middle-aged female dogs (intact>)
Poodles, collies, westie terriers, danes, rotties
Hx of patients with hypoadrenocorticism
Waxing and waning (on and off)
+/- V/D responsive to fluids, abx and steroids
Weakness and leth
CS associated with hypoadrenocorticism
Depression, leth, weakness, anorexia, dehy
PU/PD, bradycardia, abdominal pain, regurg. hypotension, acute collapse
CBC of hypoadrenocorticism
Anemia of chr. dz
Marked anemia secondary to GI hemorrhage
+/- hyperproteinemia
Reverse stress leukogram
Chemistry of hypoadrenocorticism
Hypo-natremia,-cholermia, -glycemia, -albuminemia
Hyper-kalemia, calcemia
Na:K <25:1
Azotemia (dehy/ hypotension- ↓ GFR, upper Gi hemorrhage)
Atypical addison’s
Electrolyte changes won’t occur
Gluco deficient and normal aldosterone
UA of hypoadrenocorticism
Low USG due to PU/PD
May ↑ with dehy (if medullary washout not occured)
ECG changes with hypoadrenocorticism
Hyperkalemia induced changes →bradycardia, tall T waves, wide QRS, flat P waves → atrial standstill
Diagnostic imaging of hypoadrenocorticism
Rads: hypovolemia maybe megaesophagus
U/S: adrenals small or poorly visualized
ACTH stimulation test
Definitive for hypoadrenocorticism
If pre and post <1 = diagnostic
Not addison’s if 2x the baseline cortisol
Tx for adrenocorticol crisis
Correct hyperkalemia and hypotension
Crystalloids @ shock dose (LRS)
Maintenance fluids with Na and dextrose
Dexamethasone
Glucocorticoid supplementation
Hypoadrenocorticism maintenance therapy
Fludrocortisone acetate daily
Pred with DOCP therapy
Mineralocorticoid supplementation
Hypoadrenocorticism maintenance therapy
Desoxycorticosterone pivalate (most common, q25d)
Fludrocortisone acetate daily
Hyperadrenocorticism
Pituitary dependent 80-85% (most microadenomas)
Adrenal dependent 15-20% (50% malignant)
Signalment for Hyperadrenocorticism
Middle aged to older dogs
Poodles, beagles, dascuhunds, cockers
Females >
Rule of thumb for Hyperadrenocorticism
Small-medium breeds more likely to have PDH
Large breeds more likely to have adrenal dependent
CS of Hyperadrenocorticism
Marked PU/PD, polyphagia, alopecia (rat tail)
Hyperpigmentation, thin skin, dermatits/ pyoderma, calcinosis cutis, panting, weight redistribution
CBC/ chem for Hyperadrenocorticism
Stress leukogram and thrombocytosis
Markedly ↑ ALP, mild to moderate ↑ ALT
Hypercholesterolemia
UA for Hyperadrenocorticism
USG <1.020
Proteinuria
Subclinical UTI
Radiograph findings of Hyperadrenocorticism
Markedly enlarged liver
Distended urinary bladder
+/- mineralized adrenals
Screening test for Hyperadrenocorticism
Cortisol: creatinine ratio
Sensitive, not specific (many false +)
Low= no cushing’s
Low dexamethasone suppression test (Hyperadrenocorticism)
Collect baseline cortisol, 4hr cortisol then 8hr (>1.4= cushinoid)
Normal: low
PDH: 4 hr= low to ↑, 8hr = ↑
Adrenal dependent: 4 hr= ↑, 8hr = ↑
Differentiating test for Hyperadrenocorticism
HDDS test (not used as much)
PDH: 4 hr= low, 8hr = low to ↑
AD: 4 hr= ↑, 8hr = ↑
When should a ACTH stimulation test be done for Hyperadrenocorticism
Concurrent illnesses
Post-stim cortisol results >18-20 = HAC
U/S for Hyperadrenocorticism
PDH: bilaterally symmetrically enlarged adrenals
AD: one large, other small and not visualized
Metastases and hyperechoic liver
Tx for PDH Hyperadrenocorticism
Trilostane: inhibits 3b-hydroxysteroid dehydrogenase
Mitostane: destroys fasciculata and reticularis
Tx for AD Hyperadrenocorticism
Sx!!
Has complications: pancreatitis, thromboembolism, DIC
Other adrenal atrophied/ not functional (need gluco and mineral supplement)
Monitoring for trilostane and mitotane therapy
T: ACTH stim levels @ wk 1,3,6,13 then q4-6m
M: ACTH stim levels @ q3-6m
Alopecia X
Pituitary hyperstimulation of reticularis layer of adrenals
Overproduction of androgens instead of cortisol
CS of Alopecia X
PU/PD/PP + similar signs as PDH
Less marked elevation of ALP
DX alopecia X
Androgen panel university of TN
ACTH stim serum samples
Elevated 17-hydroxyprogesterone, estradiol, other sex hormones
Alopecia X tx
therapies vary
Melatonin, flax seed oil
Trilostane and mitotane (less success)
Pheochromocytoma
Neoplasia of adrenal medulla: transient hypersecretion of catecholamines
Older dogs, rare in cats
CS of Pheochromocytoma
PU/PD, depression, leth., V/D
Anxiety/ restlessness, exercise intolerance, sudden blindness, tachycardia and hypertension
DX for Pheochromocytoma
U/S: one large (right) adrenal, other normal sized
Dx with histopath
CT/ MRI: determine extent of local involvement
Tx for Pheochromocytoma
Sx resection
Pre-sx stabilization: phenoxybenzamine (a-blockers) and atenolol (b-blocker)