Hyperthyroidism (Cram Set)

Question 1

What do elevated levels of alanine aminotransferase suggest?

Answer 1

Viral hepatitis, bile duct blockage, diabetes, congestive heart failure, myopathy

Question 2

What are the reasons for elevated ALT in a normal individual?

Answer 2

Fluctuate during the day

May be elevated after exercise

Question 3

Why is ALT a more significant indicator of liver damage than AST?

Answer 3

Because AST is also found in cardiac muscle, skeletal muscle, kidneys, brain and red blood cells

Question 4

What are reasons for raised AP in a normal individual?

Answer 4

Growth or pregnant women

Liver damage in diseased individuals

Question 5

Reasons for decreased bile acids in hyperthyroidism?

Answer 5

Decreased production and uptake by liver due to cell damage

Question 6

Constituents of bile?

Answer 6

Bile salts, water, mucus, fats, cholesterol

Question 7

Which nerve must you be especially careful of in a thyroidectomy?

Answer 7

Recurrent laryngeal nerve

Question 8

What is Horner’s syndrome and how might this occur in a post?operative complication?

Answer 8

Damage to sympathetic trunk ? leads to ptosis, miosis and enopthalmos (drooping of eyelid, constriction of pupil, sinking of eye into orbit)

Question 9

Hypocalcaemia?

Answer 9

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

Question 10

Main ways of treating hyperthyroidism?

Answer 10

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

Question 11

Hyperthyroid histology?

Answer 11

Reduced colloid ? thyroglobulin and T4 taken up by circulation
Principal cells large and cuboidal/columnar ? very active, producing lots of thyroid hormone

Question 12

Cause of hyperthyroidism?

Answer 12

Benign tumours ? caused by tinned foods, PBDEs, fish concentrate this chemical

Question 13

How are thyroid hormones synthesised?

Answer 13

Condensation and iodination of tyrosine

Question 14

Why do you test for T4 and not T3?

Answer 14

T4 tests more sensitive, T4 longer half life ? more in blood (usually bound) and lasts longer ? most converted to T3 in cells

Question 15

Extra capsular dangers?

Answer 15

Take thyroid and parathyroid glands oot

Question 16

Thyroid carcinoma histology?

Answer 16

Capsular invasion by cancerous cells
Vascularisation
Enlarged follicular cells
Metastasis
Thick fibrous capsule

Question 17

PTH actions

Answer 17

Decrease calcium ion loss from kidneys
Increase vitamin D production from kidneys
Phosphate excretion
Mobilisation of calcium from bone

Question 18

Hypocalcaemia clinical signs?

Answer 18

Muscle fatigue
Tetany
Seizures
Arrythmias

Question 19

Calcitonin actions

Answer 19

Suppress calcium reabsorption from kidneys
Suppress mobilisation of calcium from bone ? bone resorption
Promote bone formation

Question 20

Biliary disease and cholestasis tests?

Answer 20

AP and GGT

Question 21

What is cholestasis?

Answer 21

Condition in which bile cannot flow from liver to intestine (duodenum)

Question 22

How does bilirubin assess liver damage?

Answer 22

Not always associated with damage but disease.

Increased if lack of uptake by liver

Question 23

Low iodine diet not cure?

Answer 23

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

Question 24

Advantages?

Answer 24

Not as many risks as surgery; good for older cats

Controls production of thyroid hormones

Question 25

Thyroid hormone effects on metabolism?

Answer 25

Increases BMR
Increases metabolism in all tissues except gonads and brain
Increased uptake of fats/carbs from gut
Potentiates effects of glucagon, catecholamines, cortisol, GH

Question 26

Thyroid hormone effects on cardiovascular system?

Answer 26

Increased responsiveness to catecholamines promotes vasodilation
Increases inherent contractility of myocardium
Increases oxygen consumption of myocardium
Increases pulse pressure, cardiac output, heart rate, excitability, tendency for arrythmias

Question 27

Thyroid hormone effects on nervous and reproductive systems?

Answer 27

CNS development in foetus
Too little ?> sluggishness
Too much ?> excitable

May cause infertility if reduced amounts

Question 28

Hyperthyroidism leading to pulmonary oedema?

Answer 28

Left ventricle myocardium hypertrophy (hypertrophies inwards)
Thus less room for blood fill, increased pressure, decreased efficiency
Back flow into left atrium and pulmonary veins
Increase in oncotic pressure leads to pulmonary oedema
OR
clot in aorta (stagnation of blood) ?> back legs most commonly seen

Question 29

How do increased thyroid hormones cause hepatocyte damage?

Answer 29

Build up of metabolism products
Hepatic lipidosis
Thyroxine toxic to liver

Question 30

Unilateral hyperthyroidism?

Answer 30

Thyroid unaffected will atrophy

Question 31

How many pTHglands do cats have?

Answer 31

4

Question 32

Best way to diagnose hypertrophic cardiomyopathy and why?

Answer 32

Echocardiography ? can see diameter of heart walls, see blood flow, heart rate, stages of heart beat