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Flashcards in Adrenocortical Function Deck (33)
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1
Q

What does the hypothalamus release for the regulation of cortisol and aldosterone secretion?

A

Corticotropin-releasing hormone

2
Q

What does CRH cause the pituitary to release?

A

Adrenocorticotropic hormone and others

3
Q

What does ACTH cause the adrenal glands to do?

A

Secrete cortisol, aldosterone, and other steroids

4
Q

What does low cortisol promote?

A

Secretion of CRH and ACTH

5
Q

What inhibits the secretion of CRH and ACTH?

A

High cortisol

6
Q

What is aldosterone secretion promoted by?

A

ACTH, angiotensin II, hyperkalemia, and hyponatremia

7
Q

What is the secretion of aldosterone inhibited by?

A

Atrial natriuretic peptide

8
Q

What does aldoseterone promote?

A

Renal retention of Na and Cl

Renal excretion of K and H

9
Q

When is the peak secretion of cortisol in dogs and horses?

A

Morning

10
Q

When is the peak secretion of cortisol in cats?

A

Evening

11
Q

What is most of the cortisol bound to?

A

Protein: 40% transcortin, 50% albumin

12
Q

What percent of cortisol is free?

A

5-10%

13
Q

What is the half-life of cortisol in dogs?

A

1.5 hours

14
Q

What happens when cortisol and aldosterone bind to receptors in cells?

A
Gluconeogenesis
Protein catabolism
Lipolysis
Immune response
H2O balance
15
Q

What is cortisol and aldosterone removed by?

A

Hepatocytes

Some is excreted in the urine

16
Q

What is the sample needed for cortisol?

A

EDTA-plasma

17
Q

What is the sample needed for aldosterone?

A

Serum or heparinized plasma

18
Q

What is the sample needed for ACTH?

A

EDTA-plasma

19
Q

What are causes of hypercortisolemia?

A
Pituitary-dependent hyperadrenocorticism (Cushing's)
Functional adrenocortical neoplasia
Stress induced hypercortisolemia
Ectopic production of ACTH
Exogenous ACTH administration
20
Q

What are common lab findings of leukogram with hypercortisolemia?

A

Steroid leukogram

21
Q

What are common lab findings of chemistry profile with hypercortisolemia?

A

ALP in dogs
Hyperglycemia
Hypercholesterolemia
Lipemia

22
Q

What are common lab findings of urinalysis with hypercortisolemia?

A

Relatively unconcentrated, isosthenuric or hyposthenuric urine
Glucosuria in horses

23
Q

What are causes of hypocortisolemia?

A

Primary hypadrenocorticism (Addison’s)
Secondary hypoadrenocorticism (ACTH deficiency)
Atypical primary hypoadrenocorticism
Iatrogenic hyperadrenocorticism
Iatrogenic hypoadrenocorticism
Treatment with ketoconazole or trilostane

24
Q

What are common lab findings of leukogram with hypocortisolemia?

A

Absence of stress leukogram in ill, stressed patients

25
Q

What are common lab findings of chemistry profile with hypocortisolemia?

A

Hyponatremia, hypochloremia, hyperkalemia, hypercalcemia, hypoglycemia, azotemia

26
Q

What are common lab findings of urinalysis with hypocortisolemia?

A

Inappropriately low USG with azotemia

27
Q

What does the urine cortisol to creatinine ratio provide?

A

A relative rate of of urinary excretion of cortisol

28
Q

What are causes of normal to increased ACTH?

A

PDH
Primary hypoadrenocorticism
Perhaps ectopic production of ACTH

29
Q

What are causes of decreased ACTH?

A

FAN
Secondary hypoadrenocorticism
Dexamethasone injection
Therapeutic use of steroids

30
Q

What does the low-dose dexamethasone suppression test screen for?

A

PDH and FAN

31
Q

What is high-dose dexamethasone suppression test used for?

A

Differentiating PDH and FAN after hyperadrenocorticism is diagnosed

32
Q

When is aldosterone expected to be decreased?

A

In clinical hypoadrenocorticism

Primary and secondary hyperaldosteronism

33
Q

What does primary hypoadrenocorticism in dogs do to the aldosteorne:renin ratio?

A

Decreases it