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Biochem > 13 > Flashcards

13 Flashcards

1
Q

How do we investigate a patient

A

patient history
physical exam
imaging
laboratory tests

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2
Q

Why are lab tests ordered

A

diagnosis
monitor progression of disease
monitor effectiveness of treatment
screening population for diseases
to identify complications of treatment
for predicting survivability, employability
to check the accuracy of an unexpected data
to conduct research
to prevent malpractice
for education
to assess nutritional status and health of a ahealthy individual
responding to total uncertainty

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3
Q

What are the types of patient samples that are excreted

A

urine
stool
selaiva
semen
sweat
hari

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4
Q

What are types of patient sample s that are within the body

A

blood
CSF
amniotic fluid
tissue (biopsy)
bone marrow

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5
Q

What biochemical molecules could provide insights into a person’s heatlh

A

electrolytes
- potassium
- sodium

LDL cholesterol
lipids, lipoproteins

vitamins

uric acid/urea

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6
Q

Describe lab organization

A

core lab facility
- hospitals
- operates 24/7
- most essential and requested tests
- highly uatomated
- multi-analyte capabilities

special chemistry
- less frequently ordered tests
- labour intensive and often manual methods
- non-stat tests (not required imediately)

point of care testesting
- outisde of chemistry laboratory (CCU, ER, ICU, clinic)

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7
Q

Describe the core lab

A

high volumte tests (many per day)
often requriing a quick turn around time
provide critical information on client health
- electrolytes: sodium, potassium, chloride
- blood gases: pO2, pCO@, pH, HCO3, oxygen sat
- endocrine: thyroid hormones, prolactin, testosterone, estrogen, FSH, LH
- lipids: total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides
- proteins: total protein, liver proteins (albumin, immunoglobulins
- glucose:
- tumor markers
- bitamins, minerals (trace elemetns)
- toxicology

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8
Q

What are the elements of the point of care testing

A
  • urgent importance
  • affect immediate management of the patient (can be used at home)
  • available that can perform at remote locations
    (blood glucose, urinalysis, blood gases, electrolytes, cardiac markers, drug screens, COVID)
  • many are immunoassay based
  • qualitative or quantitative
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9
Q

how do tests work

A

measure an analyte as a marker to distinguish health and disease

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10
Q

What are ideal markers

A

absolutely specific for a specific disease
easily measurable
quantity reflective of severity of disease
early detection following onset of disease
not affected by other biological disturbances

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11
Q

What is troponin T
what is an example

A

highly specific marker
- marker of myocardial infarction
- found predominately in cardiac tissue
- released into hte blood following cardiac cell death

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12
Q

What is an example of a non-specific marker

A

low blood pH
- very important to know but can be caused by many pathologies
(medications or drugs, resp problems, renal problems)

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13
Q

What is the source of bllodo

A

veins
arteries
skin puncture - capillary blood

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14
Q

What is the collection method of blood

A

syringe
evacuated tube (additives, seperator gel)
intravenous lines

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15
Q

What are factors affecting choice of blood source and collection method

A

analyte under investigation
patient (vascular status, ease of collection)

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16
Q

What is blood, plasma and serum

A

whole blood is red fluid that is removed from a vein into a tube

plasma is the protein containing fluid portion of the blood, after centriugation to remove red and white blood cells and platelets

serum is the clear fluid left after blood is alllwoed to clot and then centrifuged – plasma without the blood clotting proteins

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17
Q

What happens when blood is centrifuged

A
  1. plasma (PRP)
    - plasma is fluid component of blood
    - comprises ~55% of total volume of blood
    - contains proteins, sugars, vitamins, minerals, lipids, lipoproteins and clotting factors
    - 95% of plasma is water
  2. buffy coat
    - WBC and platlets
  3. hemtocrit
    - RBC
18
Q

When is insoluble firbin clot formed

A

if blood is allowed to stand without anti-coagulants

19
Q

how does serum form

A

if blood is centrifuged, it is the fluid portioin

20
Q

What are the parts of serum

A

serum
- ~55% of total volume of whole blood
- proteins, sugars, vitamins, minerals, lipids, lipoproteins
- no clotting factors
- 95% serum is water

clotted blood
- RBC, WBC
- clotting factors (fibrin, platelets)

21
Q

What are collection tubes

A

most widely used tubes for blood collection evacuated
- negative prersure facilitates collection
- easy to use
- sterile
- universally colour-coded rubber stoppers denote tube type

22
Q

What are tubes additives

A

various anticoagulatns for the collection of whole blood or plasma
- additives for specific tests

23
Q

What do red-top tubes indicate

A

contain no anticoagulants or preservatives

used for collecting serum
- 10-15 minutes is requred to allow blood to clot before centrifuging
- used for blood bank specimens and chemistry

24
Q

What do gold-top tubes indicate

A

contain a gel that forms a physical barrier between the serum and cells after centrifugation
- no other additives present
- gel barriers may affect some lab tests

25
Q

what do grey-top tubes indicate

A

used for glucose measurement
(because after blood collection, glucose concentration ecreases because of cellular metabolism

  • contain either: sodium flouride and potassium oxalate and sodium iodacetate)
  • both presevatives stabilize glucose in plasma by inhibiting enzymes of the glycolyti pathway (glycolysis) and iodoacetate inhibits glucose-3-phophate dehydrogenase
26
Q

What do the green-top tubes indicate

A

contain either the Na, K, or lithium salt of heparin
most widely used anticoagulant for chemistry test
- can effect the size and integrity of cellular blood componenets and not recommended for hematology studies
heparin enhances the action of antithrombin, which inhibits thrombin and stops the clotting cascde

advantage: saves time, don’t need to wait for clot to form

27
Q

What do the lavender-top tubes indicate

A

contain the K-salt of ethylenediaminetetraactic acid, which chelates calcium (essentail for clot formation) and inhibits coagulation

used for hematology and some chemistires

cannot by used for K or Ca test

28
Q

What do the light blue-top tubes indicate

A

contain sodiium citrate, which chelates clacium and inhibits coagulation

used for coagulation studies becuase it is easly reversitble

29
Q

What do the brown and royal blue-top tubes indicate

A

specialyl cleaned for trace metal studies
- brown: lead Pb analysis
- royal blue: trace element studies (acid washed)

30
Q

What are the steps in obtaining a laboratory test

A
  1. test is requested by physician and ordered on the computer –> barcode is generated
  2. specimen is collected
  3. specifment nad order are transported to the lab
  4. the speciment is accessioned in the lab
  5. the specimen is processed
  6. the speciment is analyzed
  7. the results are reviewed nad verified by a technologist
  8. the results are released to the patient’s record
31
Q

What causes variations in test results

A

inter-individual variation
- age
- sex
-race
- genetics
- longterm health status

intra-indivudal vaiation
- diet
- exercise
- dtugs
- sleep pattern
- posture
- time of venipucture
- length of time tourniquet is applied

pre-analytical variation
- transport
- exposure to UV light
- standing time before sepeartaion fo cells
- centrifugation time
- storage conditions

analytical variation
- random erros
- systemic errors

post-analytical
- transcription erros
- results reported to wrong patient

32
Q

What are the types of variations

A

clinical variation: within an individual and between individuals

analytical variation: all tests have some degree of variations for repeated measurement of the same sample

33
Q

When do the factors affect the final test results

A

during sample collection
transit
during lab test
during analysis

34
Q

What are retrievable samples

A

collection easily obtained (urine, non-invasice, can get again)

35
Q

What are irretrievable samples

A

might be pediatric CSF or blood or blood marrow (cannot get again)

36
Q

What causes sieving effect

A

blocking the flow of blood with the tourniquet with eventually (too tight)

37
Q

What happens in the sieving effect

A

small molecules, water, and ions are forced out of blood vesseles and larger molecules are concentrated

increased total protein, proteins, iron, cholesterol, bilirubin

decreased potasisum

38
Q

How does the position of the body change (supoin to sitting to standing)

A

going from supine to upright reduces total blood volume by about 700 mL

may decrease by 5-15% in the supine position
- total protein
- albumin
-lipids
- iron
- calcium
-enzymes `

39
Q

What is hemolysis

A

rupture of RBC

can be due to improper collection
result in dumping cellular contents into blood (hemoglobin, iron)
mild dilution effect in some analytes

significant increase in potassium, magnesium, phosphorus

40
Q

What does hemolysis cause

A

can affect the reactions comprising specific tests
causes serum or plasma to be red and can affect tests that are colorimetric (based on colour changes)

41
Q

What is lipemia nad proteinemia

A

lots of fats and lots of protein

causes serum or plasma to become turbid

can affect colorimetric and turbidimetric based tests

can cause dilution effect
- fats and proteins are large and displace water in plasma
- can give falsely low results especially for Na

Biochem (11 decks)

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