Clinical Chemistry Flashcards Preview

Veterinary Technician > Clinical Chemistry > Flashcards

Flashcards in Clinical Chemistry Deck (51):
1

What do these tests measure and why are they important to perform?

1) They perform tests on normal substances and abnormal substances. Most chemical assays measure either the level of a dissolved substance normally carried in the blood or the amount of a substance, not normally found in blood, which has been released into the blood from damaged or destroyed cells.
2) They’re important to perform for formulating an accurate diagnosis(which can identify the organ affected), you can prescribe the proper therapy(whether it is kidney vs. liver failure), you can monitor the response to treatment(which is therapeutic drug monitoring)

2

Why is it important to review sample collection and procedures prior to performing the test?

1) For accuracy and reliability of the tests
2) You should always check: The test protocol for the type of sample required, proper anticoagulant (if any), proper sample volume
3) know if you need to have fasting samples or if postprandial is required.

3

What information is important to put on the sample and why?

It should be labeled with the date, time of collection, patient’s name, and clinic number because serious errors can result if it is not labeled immediately after the sample is collected.

4

How does hemolysis happen and how does it potentially affect the sample results?

1) Hemolysis may result when a blood sample is drawn into a moist syringe, mixed too vigorously after sample collection, forced through the needle when being transferred to the tube, or frozen as a whole blood sample
2) It can also occur when there is excess alcohol is used to clean the skin and not allowed to dry before beginning the blood collection procedure
3) Hemolysis can greatly alter the makeup of a serum or plasma sample from fluid from ruptured blood cells which can dilute the sample, resulting in a falsely lower concentration. Certain constituents normally not found in high concentrations in serum or plasma escape from ruptured blood cells, causing falsely elevated concentrations in the sample

5

How can artifactual results be identified?

Warning signs:
1) Value inconsistent with patient
2) May find other artifactual value on panel
3) May find significant variation on repeat
4) Lipemia or hemolysis do not necessitate the values are artifact but do require closer evaluation as they may change values

6

How do you correct artifacts once identified?

One artifact should cause further investigation of entire panel

7

What influences reference ranges for the chemical tests?

1) Species
2) Age

8

Where is total protein produced, how is it altered and what can that mean for the patient?

1) By the liver and the immune system
2) Can be affected by: altered hepatic synthesis, altered protein distribution, altered protein breakdown or excretion and hydration status
3) This could determine the animals state of hydration

9

What other 2 plasma proteins are found on the chemistry profile, where are they formed and how are they measured?

1) Albumin- Synthesized by hepatocytes (makes up 35-50% of the total blood protein), measured by the bromcresol green dye-binding method
2) Globulins- Alpha globulins are synthesized in the liver, gamma globulins are synthesized by plasma cells, determined by measuring the difference between total protein and albumin concentrations

10

What is an enzyme, and where are they located normally?

1) Proteins produced inside of cells which function in the acceleration of chemical reaction in biological systems.
2) They are located intracellular and for this reason, blood levels are very low in healthy animals.

11

What causes an abnormal result of enzymes?

1) Leakage
2) Increased Production

12

How are enzymes identified?

1) From either an endpoint assay or kinetic assays
2) -ase ending

13

Explain briefly the two methods of measurements of enzyme assays:

1) Endpoint assay- Uses the detection of a color complex to calculate the enzyme amount. The product of the enzymatic reaction interacts with a reagent in the slide or rotor to produce a color complex (the amount of color complex is measured by the amount of light absorbed by this color complex, which indirectly reflects the concentration of the enzyme present in the sample----The more intense the color complex, the more enzymes present.
2) Kinetic assay- Measures the rate of the enzymatic reaction as it I happening by taking serial measurements of the product as it is formed---- The rate of product formation and therefore the rate of the reaction is proportional to the amount of enzyme present. The need for high substrate concentration to move faster.

14

List the four factors that affect enzyme activity and give an example of each.

1) Inhibition: Low temps- false low values
2) Acceleration: High temps- false high values
3) Retardation: Dehydration, UV light exposure, exposure to heavy metals such as copper, mercury, lead, etc.- leading to false low values
4) Denaturation: Extremes of temp and pH

15

Why are all enzymes measured in U/L(units per liter)?

because U/L was developed to correlate results of different methods of testing; it’s the amount of enzyme, which under given assay conditions will catalyze the conversion of micromole of substrate per minute.

16

For the following enzymes, list the organ of production, what abnormal reading it would mean, write out the entire word, what artifact could affect the result: ALT

1) Alanine Aminotransferase
2) Liver specific enzyme
3) An abnormal reading could mean muscle necrosis, drugs (including corticosteroids in the dog), trauma, blood loss or shock.
4) Hemolysis and Lipemia

17

For the following enzymes, list the organ of production, what abnormal reading it would mean, write out the entire word, what artifact could affect the result: AST

1) Aspartate Aminotransferase
2) Found in hepatocytes with significant amounts in erythrocytes, cardiac muscle, skeletal muscle, renal cells, and pancreatic cells.
3) Hemolysis and Lipemia

18

For the following enzymes, list the organ of production, what abnormal reading it would mean, write out the entire word, what artifact could affect the result: SDH

1) Sorbitol dehydrogenase
2) Produced from the hepatocyte
3) unstable in serum and its activity declines within a few hours

19

For the following enzymes, list the organ of production, what abnormal reading it would mean, write out the entire word, what artifact could affect the result: ALKP

1) Alkaline Phosphatase
2) Found in liver and in osteoblasts & chondroblasts, as well as hepatobiliary cells.
3) Cannot use EDTA or oxalate anticoagulants.
4) Storing at RT > 24 hrs can elevate values

20

For the following enzymes, list the organ of production, what abnormal reading it would mean, write out the entire word, what artifact could affect the result: GGT

1) Gamma Glutamyltranspeptidase
2) Primarily found in the liver cells but a lesser degree can be found in cells of the kidneys, intestine, pancreas, and muscoskeletal system.
3) An abnormal reading could mean obstructive liver disease.
4) Prolonged contact with erythrocytes may affect the results.

21

For the following liver tests, list the origin of the compound, what an abnormal result might indicate, and what artifact could affect the results: Total Bilirubin

1) Metabolite of hemoglobin (heme portion) which is waste product of erythrocytes.
2) With an abnormal result you should suspect elevation when you have icterus, either in plasma or serum, or bilirubinuria (any amount in cat or significant amounts in the dog)
3) Artifacts that could affect the results would be Drugs (phenobarbital), lipemia and hemolysis.

22

For the following liver tests, list the origin of the compound, what an abnormal result might indicate, and what artifact could affect the results: Lipase

1) The pancreas
2) do not use EDTA (amylase & lipase require the presence of Ca +2 for activity)-Causes a false increase in both amylase & lipase.
3) Hemolysis may result in falsely elevated levels of amylase & sometimes lipase.
4) May be elevated in dogs with duodenal FB’s, chronic gastritis and gastric carcinoma-Does not correlate with severity of disease

23

For the following liver tests, list the origin of the compound, what an abnormal result might indicate, and what artifact could affect the results: Bile acids

1) Synthesized from cholesterol in liver cells.
2) Elevations would indicate liver or portal circulation problems. Also caused by microhepatica or by cholestatic disease.
3) Artifacts from lipemia and hemolysis may falsely decrease values
4) Unspecific for problem, used only as a screening test

24

For the following liver tests, list the origin of the compound, what an abnormal result might indicate, and what artifact could affect the results: Cholesterol

1) Produced by all cells in the body and liver is the primary site of synthesis in most animals, adrenal cortex, gonads (ovaries and testes) and intestinal epithelium.
2) Can be used as screening test for hypothyroidism which causes hypercholesterolemia 3) Artifact that could affect results is drugs like corticosteroids, fluoride, and oxalate anticoagulants.

25

For the following liver tests, list the origin of the compound, what an abnormal result might indicate, and what artifact could affect the results: Creatinine Kinase

1) Produced primarily by striated muscle cells and the brain.
2) Abnormalities could be from IM injections or difficult venipuncture, prolonged recumbency, surgery, vigorous exercise, electric shock, laceration, bruising, hypothermia, myositis and other myopathies.
3) Artifacts could be from sample handling, EDTA, exposure to sunlight, and a delay in the assay (sample cannot be frozen)

26

For the following liver tests, list the origin of the compound, what an abnormal result might indicate, and what artifact could affect the results: BUN

1) A nitrogenous compound, a product of amino acid breakdown (catabolism) made in the liver from ammonia.
2) An abnormal result can indicate Azotemia and Uremia.
3) Postprandial lipemia may also affect results, therefore fasting for 12-18 hours is recommended before sample collection. Urease-producing bacteria (Staphylococcus aureus, Proteus, Klebsiella sp.) can contaminate samples, resulting in decomposition of urea & thereby artificially decrease the blood values.

27

For the following liver tests, list the origin of the compound, what an abnormal result might indicate, and what artifact could affect the results: Creatinine

1) Stores energy in muscles & creatinine is formed by the decomposition of creatine.
2) High-protein diets do not affect serum creatinine levels, only muscle mass; hemolysis has little effect

28

For the following liver tests, list the origin of the compound, what an abnormal result might indicate, and what artifact could affect the results: Insulin

1) lowers blood glucose, found in the pancreas
2) Insulin target organs are liver, skeletal muscle and fat.
3) Glucose utilization depends on the amount of insulin & glucagon being produced.

29

For the following liver tests, list the origin of the compound, what an abnormal result might indicate, and what artifact could affect the results: Glucagon

1) elevates blood glucose found in the pancreas
2) acts to prevent blood glucose from plummeting too low
3) When glucose drops, glucagon is secreted. which in turn causes insulin to be secreted which will increase blood glucose by catabolizing stored carbohydrates.

30

For the following liver tests, list the origin of the compound, what an abnormal result might indicate, and what artifact could affect the results: Amylase

1) Primary source is in the pancreas but also in the liver and the small intestines.
2) Lipemia can reduce amylase activity

31

For the following electrolytes, list where they are primarily found, and if there is any associated pathology to an abnormal result: Na

1) sodium-major cation of extracellular fluid
2) sample handling- Na+ salt of heparin will falsely increase levels while hemolysis may decrease

32

For the following electrolytes, list where they are primarily found, and if there is any associated pathology to an abnormal result: K

1) potassium-found intracellular
2) hypokalemia can result from alkalosis or fluid loss due to vomiting and or diarrhea.
3) sample handling- hemolysis and clotting results in artificially elevated K+ levels.

33

For the following electrolytes, list where they are primarily found, and if there is any associated pathology to an abnormal result: Cl

1) chloride-extracellular anion
2) sample handling-serum is the sample of choice and hemolysis may decrease Cl concentrations.

34

For the following electrolytes, list where they are primarily found, and if there is any associated pathology to an abnormal result: Mg

1) magnesium-found in little over 50% in the bones and the rest can be found in all body tissues.
2) sample handling- anticoagulants other than heparin may artifactually decrease results and hemolysis increases Mg+2 levels.

35

For the following electrolytes, list where they are primarily found, and if there is any associated pathology to an abnormal result: P

1) phosphorus-80% is found in the bones, the remaining 20% or so has major functions in the body
2) alterations in P levels can indicate: renal disease, dietary over supplementation or insufficiency, ketoacidotic diabetes mellitus, and or be secondary to disturbances in Ca+2 metabolism. 3) sample handling- hemolyzed samples may falsely elevate P and serum or plasma should be separated ASAP after blood collection for accurate results

36

For the following electrolytes, list where they are primarily found, and if there is any associated pathology to an abnormal result: Ca

1) calcium-99% is found in the bones but the remaining 1% has major functions in the body including: maintenance of neuromuscular excitability and tone, and facilitation of blood coagulation
2) alterations in Ca+2 can indicate: hyper or hyperparathyroidism, hypercalcemia of malignancy, renal disease, vitamin D toxicosis, milk fever/ eclampsia, acute pancreatitis, and ethylene glycol toxicity. Ca+2 levels are inversely related to phosphorus levels.

37

Bicarbonate (HCO³-) sample handling?

Sample handling-arterial blood is the sample of choice, when HCO³- measured directly, & must be chilled in ice water & analyzed asap.

38

For Fibrinogen tests ___ is the only sample that can be used for this assay.

plasma

39

An alteration in the_____ is often the first indication of a protein abnormality

A:G ratio (Albumin to Glycogen)

40

The difference between total serum protein & total plasma protein is the total plasma protein _____, whereas the total serum protein ___ since it is removed during the clotting process.

includes fibrinogen, does not

41

T/F The total plasma protein should normally always be slightly higher than the total serum protein.

true

42

Sample handling of total protein: marked hemolysis & lipemia, hyperglycemia, & azotemia falsely _____ TP, while heat & UV light can be proteolytic & artificially ____ TP.

increase, decrease

43

Trypsin Sample Handling:handling:
1) ______ must be used, proteolytic bacteria in older samples may result in false positive results
2) Certain food recently eaten by the patient can also alter the results so the patient should be ____

1) fresh feces
2) fasted

44

T/F Trypsin is a normal component of feces and absence is abnormal

true

45

Explain the two methods to measure Trypsin.

1) Test tube method: is performed by mixing fresh feces w/ a gelatin solution in a test tube.
The gelatin contains protein which reacts with trypsin and will catabolize the protein and the solution will stay homogenous.
If trypsin is absent, the solution becomes a gel.
2) The x-ray film test: uses the same principle but uses the gelatin coating on undeveloped x-ray film.
Fresh feces are mixed w/ bicarbonate soln to a slurry & a strip of undeveloped x-ray film is placed in the slurry. If trypsin is present in the feces, the gelatin coating will be removed from the x-ray film after rinsing w/ water. No change in the gelatin coating is an abnormal test-trypsin is NOT present in the sample.

46

Which enzymes detect the exocrine components of the pancreas?

Trypsin, Amylase, Lipase

47

_____ confirms beta-cell tumor

Insulin

48

Sample handling considerations for Glucose: 1) mature RBCs use glucose for energy & if serum is not separated from a blood sample fairly quickly after collection, blood glucose will be falsely ____
2) BG can drop by a factor of ___%/hour at room temp-refrigeration slows this process & hemolysis does not affect glucose results.

1) low
2) 10%

49

The liver is the largest internal organ:
1) detoxification of certain toxins, catabolism of certain drugs-
2) amino acids, carbohydrates, lipids-
3) ___ of of bilirubin for bile
4) albumin, cholesterol, plasma protein, clotting factors-
5) bile formation-

1) elimination
2) metabolism
3) secretions
4) synthesis
5) digestion and absorption of nutrients

50

What are the two main artifacts?

lipemia and hemolysis

51

Insulins target organs are ___, ___, and ____

liver, skeletal muscle, and fat