Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

724 Clin Path > Thyroid - Ex 4 > Flashcards

Thyroid - Ex 4 Flashcards

1
Q

T3 and T4 - which is active form? which is more common in blood?

A

T3 is active form, responsible for negative feedback mechanism to pituitary and hypothalamus

T4 is major secretory product of the normal thyroid gland and is found in higher amounts in bloodstream

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Serum T3 & T4

A

Free (active) and protein-bound (inactive)

Albumin is major protein that binds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Thyroid Hormone Functions

A
  1. inc basal metabolic rate
  2. inc O2 consumption
  3. inc HR
  4. inc catabolism of fat and muscle
  5. inc protein synthesis
  6. inc erythropoiesis (may affect CBC results)
  7. inc sensitivity to catecholamines (may affect CBC results)
  8. Critical for development of differentiation of cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Canine Hypothyroidism

A

Most COMMON endocrinopathy in dogs!!

  • middle aged dogs
  • mid to large sized breeds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Canine Hypothyroidism clinical signs

A

Dermatologic: alopecia, pyoderma, otitis, etc.

Metabolic: lethargy, inactivity, weight gain

Neuromuscular: weakness, ataxia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Canine Hypothyroidism - Lab Abnormalities

A
  • Hypercholesterolemia (>75% of dogs)

* Mild, non regenerative anemia –> BM can get affected; thyroid hormones are needed for proliferating cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Pathogenesis of Hypothyroidism

A
  • Congenital - abnormal thyroid development (RARE)
  • Acquired:
  • Primary: thyroid gland doesn’t produce hormone
  • -95% of cases
  • Secondary: Pit gland doesn’t produce TSH
  • Tertiary: Hypothalamus doesn’t produce TRH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Thyroid Tests - Total T4

A
  • Serum or plasma
  • Normal thyroid function = frequently low T4 –> if low you can’t rule out hypothyroid
  • Good for excluding hypothyroidism (if normal)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Thyroid Tests - Free T4

A

Most accurate in canine testing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

If a patient is hypothyroid - what would you expect?

A

T4 to be low

T3 to be low

TSH to be high (primary acquired hypothyroid patient)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Thyroid Tests - Total T3 & free T3

A

Not recommended as sole test

Often within normal limits in hypothyroid dogs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Thyroid Tests - cTSH

A

Not good as single test

Hypothyroid dogs can have normal cTSH

&

Euthyroid dogs can have elevated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Whats the best combo of tests to dx hypothyroid in dogs?

A

fT4 & cTSH

TSH should be high and T4 should be low –> in true hypothyroid patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

More thyroid tests - TSH stimulation

A

TSH stimulation –> give dog TSH –> T4 production should increase in healthy dogs; in hypothyroid animals T4 remains low

Now uncommonly used

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Equine Hypothyroidism

A

More likely to occur in foals –> rare in adults

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Equine Hypothyroidism - Pathogenesis

A

Foals:

  • Dietary iodine deficiency
  • ingestion of goitrogen by mare

Adults:
- neoplasia

17
Q

Equine Hypothyroidism - Dx

A

tT4, fT4, tT3, and fT3 –> same as dog

TSH –> different; we can get cTSH but hard to get eTSH

18
Q

Feline Hypothyroidism

A

RARE condition

Most commonly iatrogenic –> OD of antithyroid drug or bilateral thyroidectomy

19
Q

Hyperthyroidism - Dogs

A

Dogs:

RARE

May be due to functional thyroid tumor
- most thyroid tumors are nonfunctional (don’t secrete T3 or T4)

20
Q

Hyperthyroidism - Horses

A

Horses:

RARE

May be due to functional thyroid tumor
- most thyroid tumors are nonfunctional (don’t secrete T3 or T4)

Exposure to excess iodine
- drugs, shampoos, leg paints, expectorants

21
Q

Feline Hyperthyroidism

A

Most COMMON endocrinopathy in cats

> 8 years of age (mean is 13 years)

No breed or gender predilection

22
Q

Feline Hyperthyroidism - Clinical signs

A 
weight loss
polyphagia
PU/PD
inc activity 
restlessness
GI signs (d/v) 
Skin changes 
Res signs

Basically…. “SICK CAT”

23
Q

Feline Hyperthydoiism - Lab Abnormalities

A
  1. Inc liver enzymes (ALT, ALP)
    - >90% of cats
  2. Erythrocytosis
  3. Excitement leukograms (neutrophilic, lymphocytosis)
  4. Inc BUN
    - creatinine WNL (but usually have concurrent kidney dz so this will not be the case)
    - due to inc protein catabolism
  5. Dec cholesterol
  6. Falsely dec fructosamine (can mask DM)
24
Q

Feline Hyperthyroidism - Pathogenesis

A
  • Excess production of T4 & T3 by the thyroid gland
  • almost always primary thyroid dz
  • benign proliferations much more common
  • malignant tumors uncommon
25
Q

Feline Hyperthyroidism - Dx tT4

A

Total T4

  • if high –> dx for hyperthyroidism
  • if normal to high normal –> additional tests needed, or repeat test later
26
Q

Feline Hyperthyroidism - Dx fT4

A

If normal, helps rule out hyperthyroidism

If elevated:

  • high normal tT4 w/elevated fT4 = hyperthyroidism
  • low to low normal tT4 w/ elevated fT4 = euthyroid
27
Q

Feline Hyperthyroidism - Dx T3 Suppression Test

A

Not commonly used

Give 7 doses of synthetic T3 q8hr

Collect post-administration tT4

Interpretation:
- Normal: 50% reduction in tT4

  • Abnormal: minimal to no reduction in tT4
28
Q

If increased tT4…

felines

A

HYPERTHYROID - cats

724 Clin Path (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions