Hyperthyroidism (Cram Set) Flashcards
What do elevated levels of alanine aminotransferase suggest?
Viral hepatitis, bile duct blockage, diabetes, congestive heart failure, myopathy
What are the reasons for elevated ALT in a normal individual?
Fluctuate during the day
May be elevated after exercise
Why is ALT a more significant indicator of liver damage than AST?
Because AST is also found in cardiac muscle, skeletal muscle, kidneys, brain and red blood cells
What are reasons for raised AP in a normal individual?
Growth or pregnant women
Liver damage in diseased individuals
Reasons for decreased bile acids in hyperthyroidism?
Decreased production and uptake by liver due to cell damage
Constituents of bile?
Bile salts, water, mucus, fats, cholesterol
Which nerve must you be especially careful of in a thyroidectomy?
Recurrent laryngeal nerve
What is Horner’s syndrome and how might this occur in a post?operative complication?
Damage to sympathetic trunk ? leads to ptosis, miosis and enopthalmos (drooping of eyelid, constriction of pupil, sinking of eye into orbit)
Hypocalcaemia?
Damage to parathyroid gland ?> no parathyroid hormone ?> decrease in blood calcium
PTH affects kidney to produce calcitriol (vitamin D) and increased bone calcium into blood
Main ways of treating hyperthyroidism?
Radioiodine ? destroys thyroid tissue
Surgery ? risky
Antithyroid drugs ? cats may refuse, nausea, depression, blood cell damage, itchiness
Reduced iodine diets ? long term expense, cats may refuse
Hyperthyroid histology?
Reduced colloid ? thyroglobulin and T4 taken up by circulation
Principal cells large and cuboidal/columnar ? very active, producing lots of thyroid hormone
Cause of hyperthyroidism?
Benign tumours ? caused by tinned foods, PBDEs, fish concentrate this chemical
How are thyroid hormones synthesised?
Condensation and iodination of tyrosine
Why do you test for T4 and not T3?
T4 tests more sensitive, T4 longer half life ? more in blood (usually bound) and lasts longer ? most converted to T3 in cells
Extra capsular dangers?
Take thyroid and parathyroid glands oot
Thyroid carcinoma histology?
Capsular invasion by cancerous cells Vascularisation Enlarged follicular cells Metastasis Thick fibrous capsule
PTH actions
Decrease calcium ion loss from kidneys
Increase vitamin D production from kidneys
Phosphate excretion
Mobilisation of calcium from bone
Hypocalcaemia clinical signs?
Muscle fatigue
Tetany
Seizures
Arrythmias
Calcitonin actions
Suppress calcium reabsorption from kidneys
Suppress mobilisation of calcium from bone ? bone resorption
Promote bone formation
Biliary disease and cholestasis tests?
AP and GGT
What is cholestasis?
Condition in which bile cannot flow from liver to intestine (duodenum)
How does bilirubin assess liver damage?
Not always associated with damage but disease.
Increased if lack of uptake by liver
Low iodine diet not cure?
Not removing cause (e.g. tumour)
Cats may refuse food esp. when thryoid hormone levels reach normal and their appetite returns to normal
Expensive over long term
May be deficient in other things e.g. protein
Commitment
Advantages?
Not as many risks as surgery; good for older cats
Controls production of thyroid hormones
