HypOthyroid Dz Flashcards
Describe the general effects of thyroid hormone on protein
increases the production of proteins throughout the body and results in an overall increase in all organ activity
Give examples for what the thyroid hormone normally does to the body
- improves nutrient digestion and absorption
- increases metabolism of nutrients
- increases cardiovascular function (HR, blood flow, cardiac output, strength of cardiac muscle contractions)
- helps maintain normal BP
- increases RR and depth
- increases neuronal excitability
- increases vigor of contraction and tone of muscles
Hypothyroidism
decreased production and secretion of thyroid hormones
What causes hypothyroidism?
destruction of the thyroid gland itself
What causes destruction of the thyroid gland?
- secondary to immune-mediated destruction
- neoplastic tissue
- idiopathic
What happens to the organs if there is a decreased circulating level of thyroid hormone?
- reversal of the actions of thyroid hormone on the organ system
- decrease of basal metabolic rate
- decrease in activity of other organ systems
What species does hypothyroidism often affect?
dogs
Clinical signs and PE abnormalities for hypothyroid dogs (with what causes them)
- mental dullness
- lethargy
- exercise intolerance
- weight gain –> slowed metabolism
- alopecia –> symmetric and nonpruritic; decreased growth of haircoat doesn’t allow for replenishment of coat as shedding occurs
- Pyoderma & Otitis Externa –> slowed ability of skin’s immune cells to respond to antigens properly
- weakness –> decreased neuromuscular activity
- bradycardia –> due to decreased HR
- diarrhea or constipation –> due to decreased motility of GI tract
Alterations to CBC
mild to moderate nonregenerative anemia
Alterations to serum chem and why
hypercholesterolemia
b/c thyroid hormones are important in lipid metabolism; if metabolism is slowed down, there is an increase in circulating lipid molecules that aren’t getting broken down (such as cholesterol and triglycerides)
Alterations to UA
normal
Serum Total T4 Test
- what it checks
- affected by sick euthyroid
checks circulating protein bound T4 and free T4
Yes
Free T4
- what it does
- affected by sick euthyroid
- better differentiates normal and hypothyroid dogs
- yes
Thyroid Stimulating Hormone Test (TSH)
- how it is tested
- affected by sick euthyroid
- results if hypothyroid and reason
- test in conjunction with TT4 and FT4
- minimally affected
- TSH should be elevated b/c body will try to stimulate production of more thyroid hormone, so there will be elevated levels of TSH around
What is sick euthyroid syndrome?
a term given to a condition in which non-thyroidal illness results in a decrease in circulating thyroid hormone concentrations; wait for illness to resolve and retest
(basically, if there’s an illness, the body tries to decrease metabolic rate which also decreases TSH; thyroid will look low but isn’t actually low)
