17) Analytical variables Flashcards

1
Q

anything that may affect test results, which would result in an incorrect result

A

analytical variable

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2
Q

tracks errors and strives to find solutions to sources of error

A

quality assurance (QA) department

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3
Q

4 types of preanalytical variables

A

physiologic
specimen collection
handling of specimens
interferences

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4
Q

analytes affected by diurnal variation

A

BUN, aldosterone, bilirubin, catecholamines, cortisol, testosterone, luteinizing and follicle stimulating hormone, iron, potassium, thyroxine-stimulating hormone, triglycerides, uric acid and therapeutic drugs

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5
Q

analytes affected by exercise level

A

bilirubin, creatine kinase, aspartate aminotransferase, high-density lipoprotein cholesterol, lactate dehydrogenase, myoglobin, and uric acid

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6
Q

high protein diet effects

A

increase uric acid, urea, and ammonia levels

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7
Q

caffeine effects

A

decreases pH, increases ionized calcium and catecholamine levels

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8
Q

smoking effects

A

increases glucose, triglycerides, cholesterol, LDL cholesterol, ammonia

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9
Q

alcohol short term effects

A

decreases glucose, increase in plasma lactate, increases uric acid and triglycerides

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10
Q

alcohol moderate intake effects

A

increases HDL

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11
Q

alcohol long term effects

A

increases gamma glutamyltransferase, aspartate aminotransferase and alanine aminotransferase

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12
Q

prolonged fasting effects

A

Decreases prealbumin, glucose, albumin, LD, HDL cholesterol, ketones, and insulin

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13
Q

dehydration effects

A

Results in hemoconcentration, which falsely elevates iron, calcium, sodium, and enzymes

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14
Q

NIH recommendation for patient positioning

A

patients sit for 5 minutes before collecting a specimen for lipid testing

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15
Q

effects of standing vs supine

A

decrease in aldosterone, ADH, catecholamines, renin, albumin, ALP, ALT, bilirubin, calcium, cholesterol, total protein, and triglycerides

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16
Q

examples of physiologic variables

A
  • age, ethnicity, gender
  • diurnal variation
  • exercise
  • lifestyle/diet
  • nonfasting/prolonged fasting
  • dehydration
  • pt position
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17
Q

examples of specimen collection variables

A
  • requisition errors
  • tourniquet time
  • cleaning agent
  • IV fluids/contamination
  • drug interference
  • capillary vs venous, serum vs plasma
  • additives
  • tube order
  • short draw
  • mixing
  • labelling
  • specific collections for micro
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18
Q

effects of long tourniquet time

A

increase in the ratio of cellular elements to plasma (hemoconcentration) and by causing hemolysis

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19
Q

analytes affected by long tourniquet time

A

those measuring large molecules, such as plasma proteins and lipids, or analytes affected by hemolysis, including potassium, lactic acid, and enzymes

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20
Q

betadine effects

A

falsely increase the phosphorus, uric acid and K+

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21
Q

Isopropyl (70%) alcohol cannot be used when…

A

collecting medical or legal ethanol specimens

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22
Q

IV draw procedure

A

not below IV
IV has been turned off for 2 – 5 min
draw a waste tube (10 mL, thrown away, usually a red top)

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23
Q

examples of IV contamination effects

A

Na and Cl may be increased, everything else diluted out.

Extremely high glucose, potassium, etc

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24
Q

analytes that require a conversion factor when EDTA plasma is used

A

cholesterol, triglycerides and HDL should be multiplied by 1.03 to be equivalent to a serum result

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25
Q

Capillary glucose values are —- higher than in venous specimens

A

1.4%

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26
Q

EDTA used for…

A

CBC’s, platelet count, ammonia, reticulosytes, sedimentation rates, A1c

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27
Q

Calcium could be less than test
Potassium could be greater than test

A

EDTA contamination

28
Q

purple top/pink top

A

EDTA

29
Q

lithium heparin used for…

A

BMP, CMP, troponin, CKMB, ionized calcium (on ice)

30
Q

lithium heparin not used for…

A

lithium

duh

31
Q

mint green with gel, dark green without gel

A

lithium heparin

32
Q

heparin general function

A

acts to activate antithrombin to prevent the formation of fibrin, which stops clotting

33
Q

sodium heparin used for…

A

cytogenetics

34
Q

dark green

A

sodium heparin

35
Q

Never in chemistry

A

sodium heparin

36
Q

balanced heparin used for…

A

Blood gases and whole blood sodium and potassium performed on a blood gas analyzer

37
Q

syringe tube additive

A

balanced heparin

38
Q

sodium oxalate fluoride used for…

A

glucose (gold standard glycolysis inhibitor), lactic acid and ethanol

39
Q

sodium oxalate fluoride not used for…

A

electrolytes, because it alters the blood cell membrane permeability

40
Q

gray top

A

sodium oxalate fluoride

41
Q

Inhibits coagulation by forming insoluble complexes with calcium ions

A

sodium oxalate fluoride

42
Q

SST/nonSST used for…

A

BMP’s, CMP’s and most chemistry tests

43
Q

SST/nonSST not used for…

A

therapeutic drug levels (in those with gel)

44
Q

Contains a clot activator to promote clotting; gel separates RBCs from serum

A

SST

45
Q

gold top with gel, red top without gel

A

SST/nonSST

46
Q

sodium citrate used for…

A

PT, PTT, INR coagulation tests

47
Q

light blue top

A

sodium citrate

48
Q

Acid citrate dextrose. Can be used for fungal cultures and bone marrows.

A

blood culture tubes

49
Q

yellow tops

A

blood culture tubes

50
Q

royal blue top

A

Metal free tube for trace metal testing. Often made of glass as plastics can contain metal ions.

51
Q

why might we use a glass tube instead of plastic?

A

Some analytes adhere to glass (vancomycin); others may be absorbed by the plastic tube if allowed to sit

52
Q

order of tube draw

A
  1. blood cultures
  2. citrate or coagulation tubes
  3. serum (SST) tubes
  4. heparin tubes
  5. EDTA tubes
  6. fluoride tubes
53
Q

….are collected in special tubes prepared by coag dept

A

pediatric APTTs and PTs

54
Q

———- tubes get vigorously shaken.

A

tuberculosis

55
Q

examples of specimen handling variables

A
  • light
  • temperature
  • specimen processing
  • prompt delivery
56
Q

examples of interfering substances

A
  • hemolysis
  • icterus
  • lipemia
  • fibrin
57
Q

analytes that must be protected from light

A

bilirubin, vitamin B12, folate, vitamin A and carotene

58
Q

Once centrifuged, plasma or serum should be separated from cells within ——–. (Unless SST or PST)

A

2 hours

59
Q

subtract bilirubin/lipemia interference by measuring with two wavelengths to eliminate the increase/decrease in absorbance

A

bichromatic analysis

60
Q

lipemia can be reduced by ——— of the sample

A

ultracentrifugation

61
Q

how to handle fibrin in serum and plasma

A

Serum: Allow blood to clot, no fibrin
Plasma: No need to wait to clot, contains fibrin

62
Q

2 types of analytical variables

A

instrument
technologist

63
Q

examples of instrument variables

A
  • imprecision
  • assay
  • power source
  • maintenance
  • calibration
  • QC
64
Q

examples of postanalytical variables

A
  • delivery of test results
  • calling critical results
  • LIS issues
  • printer malfunction
  • fax machine malfunction
  • file results in wrong chart
65
Q

example of critical result call documentation

A

Results called to Jane Smith, RN by Mindy D Lampe at 2:30 PM on 11/12/2018 and read back verified.