Canine Hyperadrenocorticism + Canine Hypoadrenocorticism, Pheochromocytoma Flashcards
What layers of the adrenal gland does ACTH work on?
- Zona Fasciculata (glucocorticoids)
- Zona Reticularis (androgens)
Majority (80-85%) of dogs with Hyperadrenocorticism have a _________ tumor secreting excess ______
Pituitary, ACTH
(Pituitary tumor > adrenal tumor)
True or False: Most Pituitary dependent HAC are microadenomas
TRUE
(10-20% are macroadenomas which can cause compression and neuro signs)
What is an important consideration when taking a single ACTH and cortisol sample on a dog with PDH?
ACTH is secreted in bursts, if taking 1 sample ACTH and Cortisol can appear normal… look at AUC over time
What can be visualized on ultrasound of the adrenal glands in patients with PDH?
Bilateral hyperplasia due to excessive secretion of ACTH from the pituitary gland
What can be visualized on ultrasound of the adrenal glands in patients with ADH?
Unilateral hyperplasia or normal size of 1 gland, the other is atrophied and small
Do dogs with ADH have a benign or neoplastic tumor of the adrenal gland?
50:50 adenoma or carcinoma
What would you expect the CRH, ACTH, and cortisol levels to be in a patient with ADH?
↓ CRH
↓ ACTH
↑ Cortisol
(Adrenal gland secreting too much cortisol independent of feedback loop)
What can be visualized on ultrasound of the adrenal glands in patients with iatrogenic HAC?
Bilateral adrenal gland atrophy from exogenous steroids suppressing ACTH
At what age in dogs is HAC typically seen?
Middle to older age dogs
Is there a sex predilection for dogs with HAC/Cushings?
Yes, female > male
What breed of dogs are predisposed to developing HAC/Cushings?
PDH/ADH : poodles, dachshunds, terriers, GSD
+ labradoodles
What clinical signs can be seen in dogs with HAC?
(Cushings - 5 P’s!!)
- PU/PD/PP
- Pot belly
- Panting
- Muscle weakness
- Obesity
- Bilateral alopecia
- Calcinosis cutis
- Thin skin
True or False: Both hypothyroid and Hyperadrenocorticism patients tend to have thick skin
FALSE
HypoT = thick skin
HAC = thin skin
What are the associated complications in HAC/Cushings patients? (8)
- Hypertension
- Proteinuria
- Hypercoagulable state (PTE/ATE)
- UTI
- Calcium oxalate uroliths
- Pancreatitis
- Diabetes mellitus
- Poor wound healing
List the findings on CBC, Chem, and UA from a dog with HAC
CBC:
- Stress leukogram
- Thrombocytosis
Chem:
- ↑ ALKP, ↑ ALT, ↑ BA, ↑ Cholesterol, ↑ triglycerides
- mild ↑ BG
- ↑ Na, ↓ K
UA:
- USG: < 1.015, often < 1.008
- UTI (clinically silent, must do C&S)
HAC in dogs can cause hepatomegaly. How does this appear on ultrasound?
Hyperechoic liver
How is Urine Cortisol: Creatine ratio implemented in the diagnosis of HAC?
- Screening test
- High sensitivity, low specificity
- If ↓ UCCR = unlikely HAC
- If ↑ UCCR = not specific for HAC, can be a hint
What is the GOLD standard test for assessment of Iatrogenic HAC?
Iatrogenic HAC = Iatrogenic addisons
- ACTH stim test
What results would you expect from an ACTH stim test performed on a PD-HAC patient?
- Hypersecretion of cortisol levels in response to ACTH injection
What results would you expect from an ACTH stim test performed on a AD-HAC patient?
- Hypersecretion of cortisol levels in response to ACTH injection
What is the GOLD standard test for diagnosing HAC?
LDDS test
(take blood sample, give Dexamethasone, then measure cortisol at 4 and 8 hrs)
What results would you expect from an LDDS test performed on a PD-HAC patient?
- Dexamethasone will lower cortisol levels at 4 hrs (75% of cases), then elevates again by 8 hrs
What results would you expect from an LDDS test performed on a AD-HAC patient?
- Elevated cortisol @ 4 hrs and 8 hrs, no suppression
- Dexamethasone suppresses CRH and ACTH
- ADH is from adrenal mass secreting too much cortisol, so LDDS won’t be effective at suppressing cortisol
If measuring endogenous ACTH, what would you expect the levels to be in a dog with ADH vs PDH?
ADH: Low ACTH
PDH: High ACTH
When would mitotane be used over trilostane in treatment of HAC?
- Used for carcinogenic adrenal tumors to destroy mets
- Destroys the adrenal cortex and can cause iatrogenic addisons
- Addisons better than neoplasia i guess
What hormone regulates glucocorticoid secretion?
ACTH
What is the difference between typical vs atypical addisons?
Typical: deficiency in glucocorticoids (cortisol) and mineralocorticoids (aldosterone)
Atypical: deficiency in glucocorticoids only
How is the medical management different in typical vs atypical addisons?
Typical:
- Needs Dexamethasone/Prednisone + Fludrocortisone acetate or DOCP
Atypical:
- Only needs glucocorticoid replacement (Dexamethasone/Prednisone)
Do typical or atypical Addisonians present with worse clinical signs?
Typical addisons (worse CS due to mineralocorticoid deficiency)
What is the consequence of a mineralocorticoid deficiency?
- Inability to conserve Na+ → hypovolemia and hypotension
- Lack of aldosterone leads to K+ retention → myocardial excitability (cause of death)
What is the main mineralocorticoid lacking in typical Hypoadrenocorticism patients?
- Aldosterone
What layers of the adrenal gland are affected in atypical hypoadrenocorticism patients?
- only the zona fasciculata
- Lack of glucocorticoids (cortisol)
What layers of the adrenal gland are affected in typical hypoadrenocorticism patients?
- Zona glomerulosa and Zona fasciculata
- Lack of glucocorticoids (cortisol) + mineralocorticoids (aldosterone)
What age of dogs present with hypoadrenocorticism?
Young to middle age
Is there a sex predilection for dogs with hypoadrenocorticism?
Female > male
What clinical signs can be seen in dogs with hypoadrenocorticism? (7)
Usually waxing/waning non specific CS
1. PU/PD
2. Poor appetite/anorexia
3. Vomiting/Regurg
4. Diarrhea
5. Shaking, shivering, tremors
6. Collapse
7. Hematemesis, hematochezia, melena
What would you expect the following PE findings to be from a patient with hypoadrenocorticism?
HR:
Temp:
Femoral pulses:
CRT:
BP:
HR: ↓↓↓ Bradycardia
Temp: ↓↓↓ Hypothermia
Femoral pulses: ↓ weak
CRT: > 2, prolonged
BP: ↓↓↓ (from hypovolemia)
What is the treatment protocol for fixing electrolyte imbalances associated with hypoadrenocorticism?
( ↓ Na, ↑ K ) Treating hyperkalemia
- Calcium gluconate (heart protective)
- Insulin (pushes K+ intracellularly to ↓ K+)
- Dextrose IV (glucosuria will pull K+ into urine)
What are the main electrolyte changes seen in patients with typical hypoadrenocorticism?
↑ K, ↓ Na, ↓ Cl
What is the treatment plan for a patient with hypoadrenocorticism?
- IV fluids
- Address hyperkalemia (calcium gluconate, dextrose, insulin)
- Dexamethasone or Prednisone to replace glucocorticoids
- Fludrocortisone or DOCP to replace mineralocorticoids
What clinical signs can patients with pheochromocytoma present with?
- Himb limb edema
- Collapse
- ABD distension
- Acute blindness
- Epistaxis
- Vomiting
(may be intermittent)
What physical exam finding is not seen with pheochromocytoma?
A. Tachycardia
B. Retinal hemorrhage
C. Hypothermia
d. Hind limb edema
C. Hypothermia
(Pyrexia/Fever)
List the physical exam findings that can be seen in patients with pheochromocytoma
- Normal PE is common
- Inc lung sounds due to pulmonary hypertension
- Tachycardia, arrhythmias, murmur
- High/normal BP
- ABD mass
- Pyrexia (fever)
- Signs of retinal hypertension
- Hind limb edema
List the Ddx for systemic hypertension
- CKD
- HyperT
- Hyperadrenocorticism / Cushings
- Hyperaldosteronism / Conns
- Acromegaly
- Pheochromocytoma
How can catecholamines be measured to diagnose pheochromocytoma?
- Measure metabolites in urine/blood → Normetanephrine, Metanephrine, Vanillymandelic acid
How is pheochromocytoma treated?
- Control hypertension (Phenoxybenzamine, Prazosin)
- Surgical removal (risky, massive arrhythmias) - treat with Esmolol
What is the prognosis of pheochromocytoma?
- 50% malignant in dogs, if benign and successful surgery can have normal life
- Variable in cats
Which of the following has a longer survival time: PDH or ADH?
- PDH longer survival because it’s benign
- ADH 50:50 adenoma or carcinoma with metastasis
What diagnostics must be performed prior to surgery on a Cushings patient?
CT/MRI - assess for mets, invasion of CVC, angiography
List the Ddx for a palpable adrenal mass
- Hyperadrenocorticism
- Hyperaldosteronism (Conns)
- Pheochromocytoma
- Non secretory adrenal tumors
A patient is presenting with non specific, chronic, mild waxing and waning GI signs. Bloodwork shows hyperkalemia and hyponatremia. What is the 1st test you should run if suspect Addisons?
- Start with basal cortisol
- If ↑ cortisol, rules out Addisons = “pseudoAddisons”
- If ↓ basal cortisol, confirm with ACTH stim test
A patient presenting collapsed in an Addisonian crisis. What is the first test you should perform?
ACTH stim
When should basal cortisol levels vs ACTH stim test be used in hypoadrenocorticism patients?
- Basal cortisol if patient showing non specific CS of addisons
- ACTH if in addisonian crisis, collapsed, or if basal cortisol comes back ↓
A patient presenting collapsed in an Addisonian crisis is managed with fluids and started on Dexamethasone and DOCP. On 2 week recheck, the patient is hypokalemic and hypertensive. What could be the cause?
DOCP can cause hyperaldosteronism (too much aldosterone) resulting in ↓ K+ and ↑ BP
What dog breed is susceptible to side effects from DOCP?
Labradoodles
What is “pseudoAddisons”?
Patient presenting collapsed with CS of addisons, ↓ Na+, ↑ K+ but normal cortisol and aldosterone levels
Bradycardia in a collapsed or shocky dog should raise suspicion of ____________
Hyperkalemia (Addisons)
Is primary or secondary hypoadrenocorticism more common in dogs?
Primary - destruction of adrenal gland causing low cortisol
(Idiopathic, immune mediated, neoplasia, hemorrhagic infarction, iatrogenic)
What is the cause of secondary hypoadrenocorticism in dogs?
- Lack of ACTH secreted from pituitary (less common) results in atypical Addisons (loss of only glucocorticoids)
- exogenous steroids
What layers of the adrenal gland are affected by secondary hypoadrenocorticism?
- Zona fasciculata only
- Lack of glucocorticoids only (from lack of ACTH from pituitary)
What is the most common cause of atypical Addisons?
(Secondary hypoadrenocorticism)
Addisons secondary to exogenous steroids (dec ACTH = atrophy of zona fasciculata, mineralocorticoids unaffected)
