44 Disorders of the Adrenals II

Angiotensin II from the lungs triggers aldosterone

note: NOT the pituitary, because ACTH plays a minimal role in aldosterone secretion

The point of Aldosterone being released by the adrenal gland is to help retain sodium and waste potassium. What other chemical triggers aldosterone?

1. decreased extracellular volume (like from hemorrhage)

2. increased serum potassium concentration (and increased intracellular Ca)

In general, what two conditions trigger the adrenals to secrete aldosterone?

Deficiency of BOTH mineralocorticoids (aldosterone) and glucocorticoids (cortisol)

What hormones are the problem with PRIMARY Addison's disease (the more common)?

PRIMARY: increased ACTH but low cortisol

SECONDARY: decreased ACTH AND low cortisol

What is the difference in amount of ACTH present with primary (idiopathic) versus secondary Addison's?

ONLY glucocorticoids (cortisol) deficiency

What hormones are the problem with SECONDARY Addison's disease?

SECONDARY

Is chronic exogenous glucocorticoid administration more likely to cause *primary or secondary* addison's?

Primary

Are immune mediated processes or drugs like Mitotane and Trilostane more likely to cause *primary or secondary* Addison's?

Young to middle age FEMALES, esp. standard poodles and west highland white terriers (westies)

What is the signalment typical of Addison's disease?

GI and renal disease

What "great imposter" problems might Addison's present as in dogs?

Non-regenerative anemia, eosinophilic, NO STRESS LEUKOGRAM

Azotemia (inc. BUN/creatinine, mostly from the hypotension/dehydration), low serum sodium, elevated serum potassium, low Na:K ratio (under 27:1), hypoglycemia (from the dec. cortisol)

What are the most common laboratory findings of Addison's?

Dehydration, hypovolemia, weak pulses, lethargy and collapse (because remember this disease would be a dec. in aldosterone, which helps to control blood pressure in combo with cortisol), bradycardia, PU/PD, stress intolerance

If you have Addison's what might some signs be?

EKG changes will be associated with hyperkalemia (if aldosterone is low body cannot waste potassium properly)

= TALL T, R DECREASED, flat/disappearing P

How might Addison's disease change an EKG?

ACTH stim test

Give ACTH to see if the adrenal glands will make cortisol. If there is no change in cortisol baseline after test, the animal has Addison's

How do you diagnose Addison's disease?

0.9% saline, Dexamethasone, Bicarb, 50% dextrose for hypoglycemia, Insulin with glucose to lower potassium

What can you give to Addison's patients to help treat an acute crisis?

Dexamethasone is a synthetic cortisol.

Remember the negative feedback loop = if you give Dex. to an animal with hyperadrenocorticism, the negative feedback should respond and stop making cortisol.

However, because it is a synthetic cortisol, it can be used to supplement hypo patients, like those with Addison's

Why does it make sense you can give dexamethasone to test for Cushings (hyperadrenocorticism) but treat Addison's?

Mineralocorticoids (aldosterone analogs): either Desoxycorticosterone pivalate INJECTION or Fludrocortisone Acetate ORAL

Glucocorticoids: either prednisone or prednisolone

note: you have to give both a mineralocorticoid AND glucocorticoid because primary addison's has a decrease in both, so you must address both deficiencies

What medication can you give for MAINTENANCE of Addison's instead of dexamethasone longer term?

a. Desoxycorticosterone pivalate

Which mineralocorticoid to treat Addison's is an INJECTION given every 25-29 days:

a. Desoxycorticosterone pivalate

b. Fludrocortisone Acetate

b. Fludrocortisone Acetate

Which mineralocorticoid to treat Addison's is an ORAL medication given daily:

a. Desoxycorticosterone pivalate

b. Fludrocortisone Acetate

Excellent

What is prognosis like with Addison's if there is good owner compliance?

Primary Hyperaldosteronism

What is "Conn Syndrome"

PRIMARY: Decreased renin

SECONDARY: Increased renin (often from dec. effective blood volume)

note: Primary hyperaldosteronism originates from the adrenal glands overproducing aldosterone, which suppresses the kidneys from releasing renin. Secondary hyperaldosteronism is a reaction to a stimulus, such as low blood flow to the kidneys, that causes high renin to be released, which in turn triggers the adrenal glands to produce more aldosterone.

What is the difference in Renin levels between Primary and Secondary Hyperaldosteronism?

Primary (Conn Syndrome)

Which form of hyperaldosteronism involves autonomous secretion of aldosterone?

Hyperaldosteronism

What is this cat likely suffering from?

HYPOkalemia

HYPERnatremia

What are the primary electrolyte changes in animals with hyperaldosteronism?

hyperaldosteronism

A cat presents with profound muscle weakness, ventral cervical flexion, difficulty walking and cardiac arrhythmia. You have ruled out neuro causes. You see the CBC/Chem shows hypernatremia and hypokalemia. Thoughts?

SLOW IV infusion of KCl, Spironolactone (a K sparing diuretic that blocks aldosterone).

May use amlodipine for hypertension

How can you treat hyperaldosteronism?

ADDISONS: HYPERKALEMIA, hyponatremia

Hyperaldosteronism: HYPOKALEMIA, hypernatremia

What is the difference between what Addison's and hyperaldosteronism do to potassium and sodium?