Hypoadrenocorticism Flashcards
1
Q
Hormone
A
- chemical messenger
- Secreted from a ductless gland
- Emptied directly into the circulation
- Transported by blood to alter the function of a target organ
- Usually has multiple actions
- Present in small concentrations
2
Q
Relative proportions of each zone of the adrenal gland
A
- Zona glomerulosa (15%)
- Zona fasciculata (75%)
- Zona reticularis (10%)
- Medulla
3
Q
Hormone secreted by zona glomerulosa
A
Aldosterone
4
Q
Hormone secreted by zona fasciculata
A
Cortisol
5
Q
Hormone secreted by zona reticularis
A
Sex hormones
6
Q
Hormone(s) secreted by adrenal medulla
A
Epinephrine and Norepinephrine
7
Q
Peripheral effects of cortisol
A
- Vascular tone
- Gluconeogenesis/Glycogenolysis
- Stimulation of erythropoiesis
- Anti-inflammatory
- Adaptation to stress
8
Q
What system regulates Aldosterone?
A
- RAAS
9
Q
What is aldosterone released in response to?
A
- Hypovolemia, hyponatremia, hyperkalemia
- Via Angiotensin II
10
Q
Primary functions of Aldosterone (electrolytes)
A
- Increased sodium and chloride reabsorption (SAVE SODIUM)
- Increased potassium and hydrogen secretion (PEE POTASSIUM)
11
Q
Primary (adrenal gland lesion) cause of hypoadrenocorticism (#1 cause)
A
- Immune mediated destruction of adrenal cortex
12
Q
How much of the adrenal cortex must be destroyed for clinical signs (usually)?
A
- > 85-90% of adrenal cortical destruction
- Most cases are 95%
13
Q
Other primary (adrenal gland lesion) causes of hypoadrenocorticism
A
- Iatrogenic destruction
- Drugs (mitotane, trilostane)
- Suppression by exogenous steroids
- Neoplasia
- Granulomatous disease
14
Q
Secondary causes of hypoadrenocorticism (Pituitary gland lesion)
A
- RARE
- Decreased ACTH
15
Q
Typical Addisonian
A
- Destruction of zona glomerulosa and fasciculata
- Deficiency of cortisol (glucocorticoid) and aldosterone (mineralocorticoid)
16
Q
Atypical Addisonian
A
- Destruction of zona fasciculata only (?)
- Signs of cortisol deficiency only
- No electrolyte changes
- This is why you can’t rule out Addison’s even if you don’t see changes in electrolytes
17
Q
Does atypical really exist?
A
- May be another mechanism allowing for maintenance of electrolytes even without aldosterone present
18
Q
Typical age of Addisonian patients
A
Young to middle aged
19
Q
Typical sex of Addisonian patients
A
Females may be more predisposed
20
Q
Typical breeds of Addisonian patients
A
- Standard poodles***
- Portuguese water dog
- Nova Scotia Duck Tolling Retriever
- Bearded Collie
- Others: Great Danes, Westie, Saint Bernard, etc.
21
Q
Acute signs of Addisonian crisis
A
- May present recumbent, shocky
- Threatening crisis
22
Q
Chronic signs of Addison’s
A
- “waxing and waning”
- History of GI signs, etc., that resolve on their own with supportive care (especially fluids)
- PU/PD, weakness/lethargy, weight loss
23
Q
Physical exam findings of Addison’s
A
- Non-specific findings
- Changes may be vague or absent
- Weakness, dehydration, pale mucous membranes, decreased pulse strength, bradycardia, hypothermia
24
Q
Most common CBC changes with Addison’s
A
- No stress leukogram (92%)
- Eosinophilia (20%)
- Lymphocytosis (10%)
- Non-regenerative anemia (27%) - may be masked by dehydration
25
Pathophysiology of non-regenerative anemia in Addison's
- Steroids play a role in erythropoiesis, so chronically can have an anemia
26
Common Urinalysis in Addison's
- Isosthenuria even with dehydration (60%)
27
Pathophysiology of isosthenuria in Addison's
- Medullary washout due to low sodium
28
Common chemistry panel findings in Addison's
- Hyponatremia
- Hyperkalemia
- Azotemia
- Hyperphosphatemia
29
Less common chemistry panel findings in Addison's
- Hypercalcemia (unknown mechanism)
- Hypoalbuminemia (GI loss, possible hepatopathy)
- Hypoglycemia (lack of glucocorticoids)
- Hypocholesterolemia (melena, GI signs can lead to hypocholesterolemia)
- Elevated liver enzymes
30
Clinical signs of Addison's associated with Cortisol deficit
- Vomiting Diarrhea
- Hypoglycemia
- Maintenance of vascular tone
31
Clinical signs of Addison's associated with Aldosterone deficit
- Polyuria/polydipsia (possible some contribution from glucocorticoids)
- Hyperkalemia
- Hyponatremia
32
General signs of Addison's that are a combination of the Aldosterone and Cortisol signs
- Lethargy/Weakness
- Collapse
- Hypovolemic shock
33
Na:K ratio with Addison's
- K is high and Na low with "Typical Addison's" (Na:K ratio <27)
- Electrolytes normal with "Atypical Addison's (can still progress to clinical form)
- There are other things that can cause a ratio <27 (NOT PATHOGNOMONIC)
34
Baseline cortisol <2 µg/dL Meaning
- If cortisol <2 µg/dL = NOT DIAGNOSTIC - need ACTH stimulation to confirm
- YOU WOULD HAVE TO COMMIT TO STIM-ING THE ANIMAL!
- Very suspicious but NOT diagnostic
35
Baseline cortisol >2 µg/dL Meaning
- NOT Addison's
36
ACTH stim overview for Addison's
- Gold standard
37
ACTH Stim Test Protocol
- Give cosyntropin IV and measure cortisol 1 hr post administration
38
ACTH Stimulation tests consistent with Addison's
- Most Addisonian patients have pre and post cortisol values <1 µg/dL
- Value <2 µg/dL = Addison's
- Value >2 µg/dL = Not Addison's
39
Treatment for Acute Addisonian crisis
- IV fluids, supportive, and symptomatic care
- Get all blood work and perform an ACTH stim test
- If you are suspicious of Addison's and patient is unstable, then start glucocorticoids
- Ideally perform stim first, but if you can't then use dexamethasone (NOT PRED)
40
Rationale for fluids in Addison's
- Volume replacement
- Fluids will likely also help correct electrolyte imbalances
- Be cautious about correcting sodium too rapidly
- Wait until sodium levels are safe to administer a mineralocorticoid (otherwise you can correct sodium too quickly, which is also dangerous)
41
How long will treatment for Addison's last?
- LIFELONG TREATMENT NEEDED
42
What are the mainstays of treatment for chronic Addison's?
- Glucocorticoids (prednisone): oral
- Mineralocorticoid (DOCP or Percortin): IM injection
- Glucocorticoid and Mineralocorticoid (Florinef): oral
43
Prednisone treatment for Addison's
- Daily administration
- Give at physiologic doses (~0.1-0.25 mg/kg/day)
- Increase dose during stressful or exciting events
44
DOCP treatment frequency
- Given every 25-30 days
45
Price of DOCP
- $$$$$
46
Florinef frequency
- Daily
47
Florinef overview
- Fludricortisone acetate
- Glucocorticoid and mineralocorticoid
- Difficult to manipulate tablet size
48
Florinef challenges
- Can be difficult to accurately dose for glucocorticoid amount
- May be too much for some
- Others may need additional prednisone
49
Florinef cost
- Often less expensive than DOCP
50
Monitoring for DOCP
- Check electrolytes 14 days after starting
- Then check every 25-30 days to determine maximal duration possible between injections
- Once controlled - check electrolytes every 6 months
51
Glucocorticoid monitoring
- Based on clinical signs
- If pred side effects seen (PU/PD, polyphagia), may need to decrease dose
- If GI signs then may be too low
52
Prognosis of Addison's
- Good
- Quality of life can be excellent with vigilance and proper care
- Medications need to be given correctly and on schedule to prevent crisis and possible death
- Can be cost prohibitive as medications are expensive
