Digestion & Metabolism 2: Thyroid Diseases

Question 1

what is COLLOID?

Answer 1

COLLOID is present in THYROID & acts as PRECURSOR of THYROID HORMONES

Question 2

FORMATION of THYROID HORMONES comes from ____ which we get through ____

formation is FACILITATED by WHAT enzyme? this is important because…

Answer 2

IODINE, DIET

ENZYME = THYROID PEROXIDASE
–> IMPORTANT because we can TARGET THIS ENZYME with DRUGS to SUPPRESS THYROID PEROXIDASE in HYPERTHYROIDISM

Question 3

MOST of T3 and T4 in PLASMA will be….

when ACTIVATED…

Answer 3

BOUND TO PROTEINS in PLASMA

when PHYSIOLOGICALLY ACTIVATED, T3 and T4 ARE FREE

Question 4

T____ is MORE active than T____

T3 is made in ___ by…

if we want to measure the ACTION of thyroid, we should measure…

Answer 4

T3 MORE ACTIVE THAN T4

T3 is made in PERIPHERY by DEIODINATION of T4

if we want to measure ACTION of thyroid = T4

Question 5

NEGATIVE FEEDBACK cascade of THYROID? (5 steps)

Answer 5

1. hypothalamus makes TRH
2. stimulates PITUITARY to make TSH
3. TSH acts on THYROID GLAND –> makes T3/T4
4. LIVER makes PROTEINS BOUND TO MOST OF T3/T4
5. but only T3/T4 FREE can cause NEGATIVE FEEDBACK

Question 6

thyroid MAIN FUNCTION?

why can we see ANEMIA in HYPOTHYROIDISM

Answer 6

= INCREASE METABOLISM

anemia? = because THYROID INCREASES EPO PRODUCTION, so HYPOTHYROID = NOT ENOUGH EPO

Question 7

5 MAIN thyroid hormone actions?

Answer 7

1. STIMULATES PROTEIN SYNTHESIS
2. STIMULATES CARB & LIPID METABOLISM
3. STIMULATES EPO (making RBCs)
4. STIMULATES BONE TURNOVER
5. STIMULATES NEURAL & SKELETAL DEVELOPMENT

Question 8

HYPERTHYROID DZ..

= definition?

commonality dogs vs. cats?

what AGE animals do we tend to see this in?

MOST COMMONLY caused by ___ ____, but possible to be caused by ___ yet this is ___

Answer 8

= CLINICAL CONDITION resulting from EXCESS PRODUCTION of T3/T4 by thyroid

CATS&raquo_space;»> DOGS

tend to see in MIDDLE AGE-OLD CATS

MOST COMMONLY caused by ADENOMATOUS HYPERPLASIA, but possible to be caused by CARCINOMA but this is RARE

Question 9

T4 name?

T3 name?

Answer 9

T4 = THYROXINE

T3 = TRIIODOTHYRONINE

Question 10

ADENOMATOUS HYPERPLASIA of the THYROID…

most common cause of…

see grossly..

Answer 10

MOST COMMON CAUSE OF HYPERTHYROIDISM

see MULTIFOCAL NODULES THROUGH GLAND

Question 11

ID LESION & DZ

Answer 11

ADENOMATOUS HYPERPLASIA

HYPERTHYROIDISM

Question 12

MOST cats that become HYPERTHYROID are >____ ____

Answer 12

> 8 YEARS

Question 13

HYPERTHYROIDISM…

1 common & often MISTAKEN clinical sign? how do owners see this?

6 other clinical signs?

Answer 13

1 common clinical signs? = POLYPHAGIA
–> owners MAY NOT NOTICE ANYTHING

other clinical signs?
1. WEIGHT LOSS despite RAVENOUS
2. PU/PD
3. V+
4. D+
5. POOR COAT
6. BEHAVIOR CHANGES

Question 14

PE on HYPERTHYROIDISM? (4)

WHAT IS THE MOST IMPORTANT????

Answer 14

1. HYPERACTIVE/hard to examine
2. THIN
3. ABNORMAL CARDIAC AUSCULTATION
4. PALPABLE THYROID GLAND!!!! MOST IMPORTANT

Question 15

three CBC abnormalities in HYPERTHYROIDISM?

however, they’re OFTEN ____ seen

Answer 15

1. MILD elevation in PCV
2. INCREASED MCV
3. STRESS LEUKOGRAM

however, they’re OFTEN NOT seen

Question 16

CHEMISTRY changes in HYPERTHYROIDISM? (3)

what 2 VALUES can be ELEVATED if CONCURRENT RENAL DZ?

Answer 16

1. ALP/ALT elevation
2. HYPERGLYCEMIA from STRESS
3. T4 HIGH

2 elevations in CONCURRENT RENAL DZ?
1. BUN
2. CREATININE

Question 17

diagnosis to CONFIRM HYPERTHYROIDISM?

if this test result is NORMAL but we still SUSPECT DZ, what should we do?

if STILL NORMAL, then likely…

Answer 17

TOTAL T4 CONCENTRATION!!

if we still SUSPECT DZ, then REPEAT 1-2 WEEKS since HORMONE LEVELS FLUCTUATE

if STILL NORMAL, then likely NONTHYROIDAL ILLNESS

Question 18

FREE T4 CONCENTRATION…

this CANNOT be used as a ___ test for HYPERTHYROIDISM

why?

Answer 18

SINGLE

can be ELEVATED FOR OTHER REASONS

Question 19

THYROID SCINTIGRAPHY…

helps ID what?

in HYPERTHYROIDISM, can help find ___ ___

Answer 19

helps ID FUNCTIONAL THYROID TISSUE

in HYPERTHYROIDISM, can help find ECTOPIC TISSUE

Question 20

THREE DIAGNOSTICS we should perform for FELINE HYPERTHYROIDISM?

what 2 diagnostics can we reserve if ___ ___ is NORMAL?

Answer 20

1. TOTAL T4
2. CBC/CHEMISTRY
3. UA

what 2 can we reserve if TOTAL T4 is NORMAL?
1. THYROID SCINTIGRAPHY
2. T3 SUPPRESSION TEST

Question 21

BEFORE treating, need to ask WHAT QUESTION?

the answer in HYPOTHYROIDISM should be…

Answer 21

DO I NEED TO TREAT OR NOT?

IN HYPOTHYROIDISM, SHOULD ALWAYS BE YES

Question 22

HYPERTHYROIDISM often associated with ___ ____

how does this occur? (3)

Answer 22

RENAL FAILURE

how does this occur?
1. ELEVATED T4 causes INCREASE in GFR

2. when HYPERTHYROID TREATED, causes DECREASED T4 and therefore DECREASED GFR
3. because cats usually having CONCURRENT KIDNEY DZ, this can then cause RENAL FAILURE

Question 23

HYPERTHYROIDISM treatment…

drugs will INHIBIT action of ____ ____, which is used to make…

2 names of drugs?

Answer 23

drugs will INHIBIT action of THYROID PEROXIDASE, which is used to make THYROID HORMONES

2 names?
1. METHIMAZOLE (TAPAZOLE)

2. FELIMAZOLE

Question 24

METHIMAZOLE…

used to treat WHAT?

ADVANTAGES? (2)

DISADVANTAGES? (1)

SIDE EFFECTS usually seen… and are usually ___, as well as…
1.
2.

Answer 24

TREATS HYPERTHYROIDISM

ADVANTAGES?
1. AVAILABLE & INEXPENSIVE
2. can control AMOUNT of THYROID HORMONE PRODUCED, especially important if there’s SUSPECTED RENAL DZ

DISADVANTAGES?
1. owners have to PILL ANIMAL MANUALLY BID

SIDE EFFECTS usually seen within FIRST 3 MONTHS, and are usually GI, as well as…
1. HEPATIC TOXICITY
2. IMMUNE-MEDIATED

Question 25

3 ROUTES of ADMINISTRATION for METHIMAZOLE? how long/often should we MONITOR for SIDE EFFECTS & if we need to CHANGE DOSE?

Answer 25

1. PO 2. LIQUID 3. TRANSDERMAL should monitor EVERY 2-3 WEEKS for FIRST 3 MONTHS for SIDE EFFECTS & DOSAGE

Question 26

when is THYROID SURGERY indicated? (2) advantages? (3) disadvantages? (3)

Answer 26

indications? 1. only if there's a BIG/CYSTIC THYROID MASS 2. if we need to REMOVE WHOLE THYROID advantages? 1. can be CURATIVE 2. NO LIFELONG MEDS 3. NO MONITORING BLOOD LEVELS disadvantages? 1. COST 2. requires GA 3. can cause HYPOCALCEMIA because PARATHYROID CAN BE COMPROMISED

Question 27

I-131 treatment... = what is it? advantage? (1) disadvantages? (2)

Answer 27

= RADIOACTIVE TREATMENT with RADIOACTIVE ISOTOPE OF IODINE that will be MORE READILY TAKEN UP BY NEOPLASTIC THYROID CELLS advantages? 1. 1 SQ injection can be CURATIVE disadvantages? 1. need to be AUTHORIZED to work with RADIOACTIVE MATERIALS, so animal needs to be HOSPITALIZED BY LAW ($$$) 2. animals can become HYPOTHYROID

Question 28

animals treated with I-131 for HYP__THYROIDISM lived ___ than when treated with METHIMAZOLE

Answer 28

HYPERTHYROIDISM, LONGER

Question 29

if a cat has HYPERTHYROIDISM but VARIABLE KIDNEY FUNCTION, then you should likely do a...

Answer 29

TRIAL for METHIMAZOLE

Question 30

CANINE HYPERTHYROIDISM... commonality? can be caused by... & MOST animals have ____ ___ at the time of presentation often has ___ to ____ prognosis

Answer 30

RARE in dogs can be caused by THYROID CARCINOMAS that are LARGE & INVASIVE; & MOST animals have CERVICAL MASSES at the time of PRESENTATION often has POOR to GRAVE prognosis

Question 31

what is the MOST COMMONLY DIAGNOSED ENDOCRINOPATHY in the... DOG? CAT? in WHAT AGES?

Answer 31

DOG = CANINE HYPOTHYROIDISM CAT = FELINE HYPERTHYROIDISM if MIDDLE to OLDER AGE

Question 32

CANINE HYPOTHYROIDISM... commonality? has HIGH incidence of ___ DIAGNOSIS most COMMON cause is ___-mediated ___ of the THYROID GLAND biopsy? in NECROPSY, can sometimes see...

Answer 32

COMMON disease HIGH incidence of FALSE DIAGNOSIS usually IMMUNE-mediated DESTRUCTION of the THYROID GLAND biopsy is NOT HELPFUL because IT WILL NOT TELL US FUNCTION in NECROPSY, can sometimes see SEVERE THYROID ATROPHY (almost no thyroid left)

Question 33

2 NEOPLASMS that can cause CANINE HYPOTHYROIDISM? often cause ____ ____ of the thyroid gland but this is an ____ cause

Answer 33

2 NEOPLASMS.. 1. CARCINOMA 2. SQUAMOUS CELL CARCINOMA often cause NEOPLASTIC DESTRUCTION UNCOMMON cause

Question 34

what DRUG can cause CANINE HYPOTHYROIDISM?

Answer 34

TMS

Question 35

CANINE HYPOTHYROIDISM.. occurs in WHAT aged dogs? & give specific range tends to affect WHAT size dogs? give 2 breeds intact/fixed dogs & sexes likely? (2)

Answer 35

occurs in MIDDLE-AGED dogs 4-10 YEARS tends to affect MID-LARGE breed dogs... 1. GOLDEN RETRIEVERS 2. DOBERMAN PINSCHERS SPAYED FEMALES & NEUTERED MALES LIKELY

Question 36

CANINE HYPOTHYROIDISM... clinical signs tend to be ___ common UNIQUE clinical signs? (5) which finding is MOST COMMON? can also see many ____ & ____ signs! SOMETIMES, can see ____ signs!

Answer 36

clinical signs tend to be PROGRESSIVE common UNIQUE clinical signs? 1. EXERCISE INTOLERANT 2. CONSTIPATION --> MOST COMMON 3. MENTAL DULLNESS 4. ANOREXIA 5. HEAT-SEEKING can also see many DERMATOLOGIC & NEUROMUSCULAR signs! SOMETIMES, can see REPRODUCTIVE signs!

Question 37

DERMATOLOGIC signs in CANINE HYPERTHYROIDISM? (4)

Answer 37

1. DULL, DRY FLAKEY COAT 2. SECONDARY PYODERMA 3. SEBORRHEA 4. SYMMETRIC ALOPECIA

Question 38

in INTACT FEMALES with HYPOTHYROIDISM, causes WHAT 2 signs?

Answer 38

1. affects FERTILITY 2. DECREASES LIBIDO

Question 39

CONGENITAL HYPOTHYROIDISM commonality?

Answer 39

RARE

Question 40

2 CARDIOVASCULAR signs in HYPOTHYROIDISM?

Answer 40

1. BRADYCARDIA 2. CARDIAC ARRHYTHMIAS

Question 41

MYXEDEMA COMA... can be a sign associated with WHAT DZ? commonality? animals often present...

Answer 41

can be associated with HYPOTHYROIDISM EXTREMELY RARE animals often present COMATOSE/NEUROLOGICAL

Question 42

WHY is CANINE HYPOTHYROIDISM often OVER-DIAGNOSED? what SHOULD be done?

Answer 42

people usually ONLY TEST TOTAL T4 and use that as DIAGNOSIS! INSTEAD, should combine LOW TOTAL T4 with HIGH TSH

Question 43

ONE COMMON CBC finding in HYPOTHYROIDISM? which value should we take MULTIPLE measurements of? why?

Answer 43

1. HYPOCHOLESTEROLEMIA take MULTIPLE measurements of TOTAL T4 because LOW T4 CAN BE PRESENT FOR MANY REASONS

Question 44

if you have to choose ONE thyroid test for HYPOTHYROIDISM, choose ___ ___ because it's....

Answer 44

FREE T4 because it's LESS AFFECTED BY NON-THYROIDAL DISEASE

Question 45

TSH test... can be used to test for ____ if POSITIVE for that disease, expect HIGH/LOW TSH BEST DIAGNOSIS for this when COMBINED with WHAT test & WHAT result for this disease?

Answer 45

TESTS FOR HYPOTHYROIDISM if HYPOTHYROID --> TSH IS HIGH, A LOT OF SUPPRESSION BEST HYPOTHYROIDISM DIAGNOSIS when COMBINED with TOTAL T4 BEING LOW

Question 46

what is the GOLD STANDARD for HYPOTHYROIDISM?

Answer 46

TSH-STIM TEST