Endocrine Diseases Flashcards
Where are T4 and T3 synthesized?
T4 synthesized 100% by the thyroid
T3 synthesized by the thyroid and created by cells systemically
In what forms do the thyroid hormones circulate?
- 99% inactive form (protein bound)
- 1% active form (unbound)
What does Total Thyroxine test (TT4) measure?
What is the gold standard?
- measures total circulating T4 (bound and unbound)
- radioimmunoassay is the gold standard
What does the Free Thyroxine test (FT4) measure?
What is the gold standard?
- measures unbound, circulating T4
- equilibrium dialysis is the gold standard
What is the most common cause of hypothyroidism in dogs?
Canine adult-onset hypothyroidism, also known as primary hypothyroidism
- auto-immune disease
What are the common clinical signs of canine adult-onset hypothyroidism?
- lethargy, mental dullness, weight gain
- cold intolerance, hypothermia, cold ears
- bradycardia
- alopecia, shedding, poor hair coat
What are the CBC and chemistry abnormalities in canine hypothyrodism?
- mild to moderate non-regenerative anemia
- fasting hypercholesterolemia and hypertriglyceridemia
Primary Hypothyroidism test results
TT4, FT4, TSH
- TT4 decreased
- FT4 decreased
- TSH increased
Euthyroid Sick Syndrome test results
TT4, FT4, TSH
- TT4 decreased
- FT4 normal to decreased
- TSH normal to increased (usually normal)
What is the most common endocrine disorder of cats?
hyperthyroidism
What are the clinical signs of feline hyperthyroidism?
- palpable thyroid slip
- tachycardia
- polyphagia with weight loss
- hyperactivity
- diarrhea
What are the CBC and chemistry abnormalities of feline hyperthyroidism?
- polycythemia
- Heinz-body formation
- stress leukogram
- mild to moderate increase in ALT
- azotemia
- altered bone metabolism
What is the single test for feline hyperthyroidism?
TT4
- increased
What disease is commonly masked in feline hyperthyroidism?
renal failure
What are the functions of PTH?
- increase plasma Ca
- decrease plasma P
What is the cause of hyperparathyroidism?
parathyroid adenoma
What are the chemistry abnormalities of hyperparathyroidism?
- hypercalcemia
- hypophosphatemia
What are the chemistry abnormalities of hypoparathyroidism?
- hypocalcemia
- hyperphosphatemia
What does ADH/Vasopressin respond to?
What does it do?
- responds to increased osmolality or decreased plasma volume
- transports aquaporins in the collecting ducts to the membrane, and stimulates their synthesis
- maximizes water reabsorption
What happens in Central Diabetes insipidus?
- no production of ADH
- no water reabsorption
What happens in Nephrogenic Diabetes insipidus?
- no response to ADH (non-functional receptors)
- no water reabsorption
Describe the ADH response test and its results
- administer desmopressin, and monitor urine specific gravity
- CDI = concentrated urine
- NDI = dilute urine
Describe the water deprivation test
- dehydrate the animal
- does it release ADH and concentrate its urine?
- PPD = yes
- DI = no
When should you not do the water deprivation test?
if the animal is:
- suspected of having renal disease
- azotemic
- dehydrated
