Endocrine

Question 1

Husband’s Endocrine Lectures

Question 2

1. Why is the owner bringing you this cat (Hx)?
2. What are your findings on PE?
   a. Ddx?
3. What are the cat’s CS?
   b. Ddx?
4. What diagnostics will you run?
   4a. Results?
   c. Dx?
5. How will you Tx?

Answer 2

1. This cat has lost weight, restless (meowing all the time), vomiting, eating a lot.
2. Thin BCS, tachycardia, decr. wt., palpable thyroid, scruffy
   a. Hyperthyroidism, DM, lymphoma
3. decr. weight, incr. appetite, vomiting, PU/PD
   b. Hyperthyroidism, lymphoma, DM
4. MDB: CBC, Chem, UA, TT4
   4a. CBC: incr. RBCs, Heinz bodies, mild stress leukogram

Chem: incr. liver enzy, azotemia, hyperphosphatemia, hyperglycemia

UA: low USG, proteinuria

TT4: elevated

c. Hyperthyroidism
5. depends on o $:

Medical tx:

Methimazole

Diet

Nuclear tx:

I¹³¹

Sx tx:

thyroidectomy

Question 4

What can be a complication of hyperthyroidism tx?

Answer 4

Occult renal dz may be uncovered when thyroid is normalized!

Question 5

What is most common cause of 1° hypothyroidism?

What species is it seen in?

Answer 5

lymphocytic thryoiditis

dogs

Question 6

What are client’s CC for hypothyroid dogs?

Answer 6

lethargic

weight gain despite not eating that much

poor haircoat/not growing back after grooming

doesn’t have any oomph to play

likes to lie in the sun all day

Question 7

What might your PE findings be on a hypothyroid dog?

Answer 7

skin changes:

symmetric alopecia

scaling

hyperpigmentation

pyoderma

incr. weight

tragic expression (myxedema)

Question 8

What diagnostics might you run for a Ddx of hyperthyroidism?

What might the findings be?

Answer 8

CBC, Chem, UA, T4 & TSH

mild normocytic/chromic anemia

hypercholesterolemia

+/- incr. ALP

low T4, elevated TSH

Question 9

What causes the disease Hypercalcemia?

Answer 9

Trick Question!!!!

Hypercalcemia is not a disease in an of itself!

It is a symptom of a disease!

Question 10

How do you tx hypothyroidism in dogs?

How long is tx?

Answer 10

Oral supplementation w/ levothyroxine

Lifelong

Question 12

What is HOGS IN YARD?

Answer 12

• H- hyperparathyroidism
• O- osteolysis
• G- granulomatous disease
• S- Spurious
• I- iatrogenic, idopathic (cats)
• N- neoplasia
• Y- youth
• A- Addison’s, acidemia
• R- renal disease (a or c)
• D- vit. D toxicosis

Question 13

If a dog were to be dx’d with 1° hyperparathyroidism what age and breed might it be?

What is the most common tumor causing 1° hyperparathyroidism?

What would be the normal physiological response of PTH in the face of high iCa⁺⁺?

Answer 13

Older & Keeshond!

Benign Functional Adenoma

PTH should be low to not stimulate the parathyroid. Even a value in normal range is not normal in the face of high iCa⁺⁺

Question 14

What are some causes of osteolytic dz that might cause hypercalcemia?

Answer 14

Osteomyelitis (bacterial or fungal)

Hypertrophic osteodystrophy

Question 15

Good image to know

Answer 15

Remember: FT4 (unprotein bound in serum) is active → intracellularly → converted either into T3 (active) or rT3 (inactive)

Question 16

What is euthyroid sick?

Answer 16

Non thyroidal illness causing a falsely decreased T4

Question 17

What are thought to be the mechanisms behind euthyroid sickness?

Answer 17

decr. TSH release

change in protein binding

decr. synth of T4

other?

Question 19

How should TT4 & TSH be interpreted when making dx of hypothyroidism?

Answer 19

Never dx only due to diagnostic testing!

TT4:

If in upper ½ of normal range → unlikely to have hypoT4

If low → either hypoT4 or euthyroid sick

If in lower ½ of normal range → may be hypoT4

TSH:

If high w/ a low TT4 or fT4→ 90% hypoT4

Question 20

What CS can be seen with hypocalcemia?

At what level does total Ca have to be for CS of hypocalcemia? iCa^++?

Answer 20

facial rubbing

seizure

lethargy

depression

coma

muscle tremors/cramping/fasciculations

Tot Ca: 6mg/dL iCa^++: o.8mmol/L

Question 21

CS of hyperCa?

Answer 21

PU/PD

Anorexia & Vomiting

Drowsiness

Weakness

Question 22

What must be done when hypercalcemia is reflected on labwork?

Answer 22

Confirm incr. in Ca is due to ionizedCa!!

iCa⁺⁺ test

thorough PE IMPERATIVE (digital rectal exam)

SYSTEMATICALLY RULE OUT CAUSES

HOGS IN YARD

Question 23

What are most common hypercalcemic syndromes?

Answer 23

Neoplasia

1° hyperPTH

CKD (mild when present)

*HyperCa may result from kidney dz or cause kidney injury!

Hypoadrenocorticism (Addison’s)