Exam 3 Clin Path

Question 1

Thyroxine (T4) is _____% synthesized by the thyroid

Answer 1

100%

Question 2

Triiodothyronine (T3) is ____% synthesized by the thyroid

Answer 2

30-40%

Question 3

Which is more potent: T4 or T3?

Answer 3

T3

Question 4

____% of thyroid hormones are circulating in the inactive/protein bound form

Answer 4

~99%

Question 5

Which hormone:

• Increases metabolic rate
• Increases oxygen consumption, stimulates erythropoiesis
• positive inotropic, chronotropic effects
• Catabolizes muscle & adipose
• Alters lipoprotein metabolism

Answer 5

Thyroid hormone

Question 6

What test should you have on a canine thyroid panel?

Answer 6

• Total Thyroxine (TT4)
• Free Thyroxine (FT4)
• Thyroid Stimulating Hormone (TSH)

Question 7

****** If a cats TT4 levels do not match their clinical signs, you should run what test?******

“HINT -HINT ;)”

Answer 7

_***FT4 ***_

it is exspensive but TT4 can be masked by euthyroid sick syndrome

Question 8

What is the gold standard test for Total thyroxine (TT4)?

Answer 8

Radioimmunoassay (RIA)

Snap ELISA test kits- high sensitivity, reliable for normal [T4]

Question 9

What is the most common way to measure TSH?

Answer 9

Immunoradiometric*

only use in dogs

Question 10

What is the most common cause of primary hypothyroidism in dogs?

Answer 10

Autoimmune disease- Lymphocytic thyroiditis

Question 11

Clinical signs of primary hypothyroidism become apparent when <____% of thyroid tissue is left

Answer 11

<25%

Question 12

What disease in dog will produce:

• Mild to moderate non-regenerative anemia
• Fasting hypercholesterolemia
• Fasting hypertriglyceridemia

Answer 12

Hypothyroidism

All due to decrease metabolic rate and decrease catabolism by the liver

Question 13

What disease causes:

• TT4 decrease
• FT4 decrease
• TSH increase

Answer 13

primary hypothyroidism

Question 14

What disease causes a decrease in TT4, FT4 and TSH?

Answer 14

Secondary hypothyrioidism

Question 15

T/F: In dogs, MOST thryoidcarcinomas do not echibit sign so abnormal thyroid function

Answer 15

True- will be normal as long as 25% of normal tissue remains

Question 16

Sick animals have a (increased or decreased) levels of TT4?

Answer 16

decreased TT4= Euthyroid sick syndrome

TSH should be normal (99% of the time)

Due to adaptive response - energy is put toward the immune system

Drug induced: Phenobarbital, Sulfonamides, Furosemide

Question 17

What drugs interfere with thyroid hormone levels?

Answer 17

1. Phenobarbital
2. Sulfonamides - block iodination
3. Furosemide
4. Glucocorticoids - changes metabolism and inhibits TSH formation

Question 18

In euthyroid sick syndrome:

• TT4 decreased
• FT4 normal to decreased
• TSH __________________?

Answer 18

TSH is normal (99% of time time)

Question 19

Which breeds tend to have lower TT4 levels naturally?

Answer 19

Greyhounds, Sighthounds, and large breeds

Question 20

T/F: No single test definitively diagnoses hypothyroidism and you should always Interpret data with clinical presentation

Answer 20

True

Question 21

____% of feline hyperthyroidism is due to functional thyroid adenomas or hyperplasia

Answer 21

99%

Question 22

Which disease will cause:

• Polycythemia (~50%) due to increase EPO
• Heinz-Body formation (NON-hemolytic anemia)
• stress leukogram (~20%)
• Elevated ALT (~90%)
• Altered bone metabolism (~20%)- change ALP
• Masked Azotemia (30%)
• increase TT4

Answer 22

Hyperthyroidism

Question 23

What are the advantages and disadvantages of Manual counting/hemocytometer?

Answer 23

• Advantages: Inexpensive, Simple & small instrument, No calibration or QC required
• Disadvantages: Time, Training, Imprecise

Question 24

What are the disadvantaged of Buffy Coat Analysis?

Answer 24

Values are estimated
Calibration Rod performed each morning

No quality assurance methods available between QC or calibrations

Question 25

What are advantages and disadvantages in in-office flow cytometry?

Answer 25

_Advantages_: reduced interference with platelet clumps and nRBC, evaluate number, size and complexity of cells, automated reticulocyte counts possible. Dot plots available for each patient. _Disadvantage_: Cost, Sample size, speed, requires extra computer, No QC materials, dot plots not printed

Question 26

Which analyzer gives you histograms of each cell count and distribution? (Manual, Buffy coat, Flow cytometry or Impedance)

Answer 26

impedance

Question 27

What are Advantages and disadvantages of Impedance?

Answer 27

_Advantages_: low cost, on-board computer, sample size, speed, QC materials available, species validation, histograms printed for each CBC, alterantive fluid analysis _Disadvantages_: looks at size only (affected by platelet clumps and nRBC), some have only 3 part analyzers

Question 28

What cells do 3 part and 5 part analyzers detect?

Answer 28

3 part: GRN, LYM, MON 5 part: LYM, MON, NEU, EOS, BAS

Question 29

T/F: Alcohol can cause sample hemolysis

Answer 29

True! If used, allow to dry before inserting needle

Question 30

T/F: MCHC and HCT are measured

Answer 30

FALSE They are calculated

Question 31

Hgb X ____ = HCT

Answer 31

Hgb X **3** = HCT approx

Question 32

What can falsely increase Hgb?

Answer 32

**Lipemia** (take fasted samples) Markedly icteric sample Lots of Heinz bodies Lyse resistant RBC

Question 33

What will these due to your MCV:(1) a tube sitting too long (2) too much EDTA

Answer 33

Tube sitting too long (RBC swelling) = **INCREASE MCV** Too much EDTA to RBC in tube (RBC shrinkage) = **DECREASE MCV** MCV is used to calculate HCT, thus these errors can cause a false HCT

Question 34

What causes afalse increase in MCHC? MCHC= (Hgb/HCT) x 100

Answer 34

**Anything that increases the Hgb or decreases the HCT** * _Hgb falsely increased by_: lipemia (measured with spectrophotometer) * _HCT falsely decreased by:_ hemolysis & not enough blood/EDTA MCHC= (Hgb/HCT) x 100 HCT= (RBC x MCV) / 10

Question 35

What can blood smears tell you, that no machine can do yet?

Answer 35

Cell Morphology Cell Inclusions Left Shift Toxicity Presence of abnormal cells Parasites

Question 36

What are the 4 chemistry analyzer techniques?

Answer 36

1. **Absorbance spectrotometry (wet)** 2. **Reflectance spectrophotometry (dry)** 3. Fluorescence 4. Electrochemical

Question 37

What it Beer's Law?

Answer 37

Determines an unknown [] an analyte in solution A series of samples with a known concentration of a specific substance is measured by how much light is absorbed Maps the linear relationship, then uses the absorbance to determine the concentration

Question 38

Which is **more** affected by interfering substance (lipemia, icterus, hemolysis): End-point Reactions or Rate Reactions

Answer 38

End-point

Question 39

What is the difference b/w the **reference range** and the **dynamic range?**

Answer 39

* Referencerange- normal/average values for a specific species * Dynamic Range- what the analyzer can accuratly read

Question 40

Abnormally Low Ca and high K in a healthy appearing animal is an indicator of what artifact?

Answer 40

EDTA contamination

Question 41

Which can be removed from a sample in-vitro: Lipemia or Hemolysis

Answer 41

Lipemia - via a exspensive ultracentrifuge ---------------------- if not removed, these can interfere with color, turbidity, volume, reactions and RBC

Question 42

Increase K and liver enzymes in a healthy animal could be due to what artifact?

Answer 42

hemolysis