Hypothyroidism & Hyperthyroidism Flashcards
T4
T3
Thyroxine
triiodothyronine
Causes of hypothyroidism
Primary?
Secondary?
Primary:
Lymphocytic_plasmacytic,thyroiditis
Thyroid atrophy
Secondary: Lack of TSH from the pituitary
Tertiary: Lack of TRH (not reported in dogs)
Tests for hypothyroidism
Total T4
Free T4 (more time & $)
TSH (high expected)
(Note: T3 varies too much to be useful)
Hypothyroidism Biochem findings
Mild,non_regenerative,anemia (30%,of,patients),
Fasting,hypercholesterolemia,(75%)
Fasting,hypertriglyceridemia,(80%),
Euthyroid Sick Syndrome drugs (Hypothyroidism)
Aspirin Glucocorticoids Meloxicam (no effect) Clomipramine (antidepressant) Phenobarbital Sulphonimides
Conditions known to decrease T4
Hyperadrenocorticism Hypoadrenocorticism Diabetic ketoacidosis Renal insufficiency Hepatic disease Peripheral neuropathies Heart failure Critical illness/ Infections/Surgery/Anaesthesia
If you expect that the hypothyroidism is immune mediated, what can you test for?
Anti thyroglobulin antibodies (ATA)
Anti T3 antibodies
Anti T4 antibodies
Hypothyroidism Treatment
Synthetic,sodium,levothyroxine,(T4) - initially a twice a day dose, then once a day dose; goal: Middle,to,high,end,of,normal,TT4,(30_50, nmol/L),Middle,to,high,end,of,normal,TT4,(30_50, nmol/L)
Hyperthyroid drugs
Methimazole - Inhibits production of T3 T4
Side effects - vomiting diarrhea & hepatotoxicity, Blood dyscrasias, facial excoriation
Clinical findings for hyperthyroidism in cats
Increased hematocrit Neutrophilia lymphopenia elevated liver enzymes Increased phosphorus Sometimes azotemia Rarely hyperglycemia Low specific gravity's Sometimes UTIs
Clinical features for hyperthyroidism
Weight loss PU/PD Polyphagia Hyperactivity Intermittent GI signs Intolerance to stress Tachycardia Murmur
Typical patient for hyperthyroidism in cats
12-13 year old cats
