Cushings/Addisons

Question 1

Know the different divisions of the adrenal cortex and what is produced there.

Answer 1

Zona Glomerulosa - aldosterone.
Zona Fasciculata - cortisol
Zona Reticularis - 17-ketosteroids and cortisol.

Question 2

Breed and age incidence of cushing’s

Answer 2

Toy and mini breeds, poodle and dachshunds have increased incidence.
Age 3-13 years (8y avg).

Question 3

What is exogenous/iatrogenic cushing’s?

Answer 3

Caused by giving large doses of glucocorticoids. Tx is slowly weaning off of the meds and giving the adrenals time to start producing again.

Question 4

Physical features of cushing’s

Answer 4

Pot bellied
Thin skin, esp on abdomen
Truncal, bilateral, symmetrical alopecia.
Occ, calcinosis cutis.

Question 5

Cushing’s functional adrenal tumor incidence and pathophys-

Answer 5

15-20% of cases.
Tumor causes excessive amounts of cortisol to be produced/released. This DOES feed back to the pituitary and cause a decrease in ACTH.

Question 6

Pituitary-dependent cushing’s incidence and pathophysiology

Answer 6

80-85% of cases.

Feedback loop is damaged by tumor and ACTH continues to be released despite high cortisol levels.

Question 7

Clinical signs of cushing’s disease

Answer 7

PU/PD, polyphagia, weight gain, weakness/lethargy, hyperpigmentation of skin and hair, testicular atrophy, and hepatomegaly. Physical appearance changes.

Question 8

Cushinoid dogs are ____coagulable.

Answer 8

Hypercoagulable.

Question 9

Lab findings for cushing’s

Answer 9

Stress leukogram (lymphopenia, eosinopenia, neutrophilia and monocytosis).
^Chol, ALP, ALT.
Proteinuria, +/- UTI.

Question 10

Endocrine dx of cushing’s

Answer 10

ACTH stim test
LDDT
HDDT
Plasma ACTH
Urine cortisol/Cr ratio

Question 11

ACTH stimulation test evaluation

Answer 11

Elevated - cushing’s
Depressed - addison’s

Abdominal U/S could then be done to see if adrenal tumor present for cushinoid animals.

Question 12

OPDDD (AKA - lysogren, mitotane)

Answer 12

Used in dogs only. Cat rapidly metabolize so ineffective. Phenobarb makes ineffective as well b/c of P450.

• Cytotoxic to all layers of adrenal cortex.
• If ACTH >10 reload dose.
• drug tox - depression, weakness, v/d, anorexia. Stop med until signs abate then restart on lower dose.

Question 13

Trilostane

Answer 13

Used in dogs and cats. Most popular drug used for PDH.

1-2 mg/kg BID, titrate to effect (as high as 3mg/kg BID)

Question 14

Cushinoid cat

Answer 14

Etiology similar to dogs. Many diabetic, testing is the same but interpretation difficult.

Question 15

LDDST interpretation

Answer 15

• Failure of suppression by atleast 50% base cortisol level by 4-8hrs is diagnostic for cushing’s disease — either PDH or ADH.
• 30% of PDH patients will have suppression of cortisol by 4 hrs and increase by 8 hrs.

Question 16

HDDST interpretation

Answer 16

Used to differientiate PDH from ADH.

*PDH - cortisol level <50% baseline at 4-8hrs post-dex..

Question 17

ACTH stimulation test interpretation

Answer 17

Measures response to synthetic ACTH.

• If pre and post <2 ug/dl - hypoadrenocorticism.
• If post is >18 patient is cushinoid but a HDDST or abdominal ultrasound needs to be done to deterine if PDH or ADH.

Question 18

Incidence of addison’s

Answer 18

Not common, but frequently undiagnosed.
No known sex predilection.
Most common in young dogs <5yr.

Question 19

Causes of adrenal insuffiency

Answer 19

Iatrogenic
Infiltrative - dz, cancer, mycosis.
Infartion
Pituitary insufficiency
OPDDD induced
Idiopathic
Autoimmune destruction

Question 20

Electrolyte abnormalities associated with hypoaldosteronism

Answer 20

Decreased Na and Cl

Increased K

Question 21

S/S of acute addisonian crisis

Answer 21

Hx of wt loss, lethargy, anorexia, +/- GI signs.
Dog presents weak or lateral recumbent.
Mentally dull.
Bradycardia, weak femoral pulses.

Question 22

Lab findings with acute addison’s crisis

Answer 22

► ± ↓ Neuts
► ± ↑ Eos
► ± ↑ Lymphs
^^^Insensitive
► ↑ K+
► ↓ Na
► ↑ BUN
► ↓ Glu (rare)
► ↓ HCO3

Question 23

Other causes of decreased Na and increased K - pseudoaddison’s

Answer 23

renal disease
GI disease
DKA, HNKD,
Chylothorax

Question 24

Dx of addisons

Answer 24

Gold standard is ACTH stim test.

Na/K <20

Question 25

Plasma aldosterone

Answer 25

Low in most addisonian dogs.
Low blood levels are independent of serum Na and K levels…. sometimes Na and K can be normal despite low aldosterone due to independent compensatory mechanisms.

Question 26

A patient presents in what you believe is an addisonian crisis. How do you treat and Dx at the same time?

Answer 26

Begin IV NaCl. Collect resting serum cortisol blood.
Give Cortrosyn IV.
Give dexamethasone IV.
Collect 2nd serum cortisol at 1 hr.

Question 27

Goals of treating addisonian crisis

Answer 27

Restore volume.
Provided glucocorticoid.
        Pred Na succinate or dexamethasone.
Provide mineralcorticoid.
        Florinef or DOCP
Reverse marked hyperkalemia.

Question 28

Maintenance tx for addison’s

Answer 28

Florinef or DOCP
+/- Prednisone
Periodic Na/K eval.

Question 29

What is DOCP?

Answer 29

Percorten-C. Tx for addison’s.
Contains only mineralocorticoid. Need to give pred with.
*OD = hypokalemic myopathy. Tx w/ KCl in fluids.

Question 30

What is Florinef?

Answer 30

Treatment for addison’s. Has both glucocorticoid and mineralcorticoid activity. Occ need to supplement with pred.

Question 31

Atypical addision’s

Answer 31

Chronic lethargy, weakness, poor appetite, wt loss.

Normal Na/K despite low aldosterone. Absent to minimal ACTH-induced cortisol response.

Question 32

Tx of atypical addison’s

Answer 32

If lytes normal: Pred

If lytes ABnormal: Pred w/ florinef (DOCP) OR percorten-V.

Question 33

What is important to remember when managing an addisonian patient?

Answer 33

Any medical or surgical stress will warrent the use of significant supplemental doses of glucocorticoids.

Question 34

Comparison between typically and atypical addison’s

Answer 34

Typical |Atypical
Na+            ↓      N or ↓
K+              ↑      N or ↑
Cl-              ↓       N or ↓
BUN           ↑       N
Cortisol       ↓        ↓
Glucose  N, ↓ ↑   N or ↓