Intro to Lab Med Flashcards

1
Q

Hematology

A

Whole blood analysis and coagulation

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2
Q

coagulation

A

clotting

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3
Q

Urinalysis

A

Urine

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4
Q

Chemistry

A

Body Fluids component, organ functions

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5
Q

Special Chemistry

A

elaborate techniques such aselectrophoresis, and manual testing methods.

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6
Q

Microbiology

A

Pathogenic microorganisms

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7
Q

Serology/Immunology

A

Antibody studies

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8
Q

Role of Lab testing

A

The decision making model
History and physical exam
Patient assessment and the differential diagnosis (hypothesis)
Deciding on a management plan

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9
Q

60-70% of heath care decision rest on clinical lab tests-

A

play crucial role in decision making

Diagnosing symptoms, deciding course of treatment, monitor response to therapy

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10
Q

Chest pain what are your differentials?

A

Use of test called CK-MB/CPK or troponins….…..enzyme/protein released from myocytes during cardiac damage…… level is elevated during an MI in the serum

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11
Q

What do you need to learn?

A

when & what to order to aid your decision

how these correlate with the physiologic condition of the patient

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12
Q

Once diagnosis is made…

A
Use in continuous management
Monitor disease course and therapeutic response
Provide information on prognosis
Information on risk of future disease
Screening tests
Detection of subclinical disease
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13
Q

PSA is a tumor marker for…

A

initial diagnosis of prostate CA then to follow and check for metastatic disease occurrence or return of CA once treatment complete

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14
Q

Are lab tests always needed?

A

some substance in the blood, urine, cerebrospinal fluid, other body fluids
ONLY AS GOOD AS SPECIMEN SUBMITTED

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15
Q

Don’t order lab tests if…

A

you know why (how will you use info)
you know WHAT to order
it will help narrow your differentials
it will change your treatment decision

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16
Q

Ordering Parameters are

A
Over 1,000 from less to very invasive
simple to complex
Cost money 
Practical limitations
Lab capabilities
Time to receive results- can you wait
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17
Q

CBC versus H&H means

A

complete blood count versus bone marrow

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18
Q

Do all labs off all tests?

A

NO, – may use reference labs or substitute one test for another- need to understand and know what information you need and best way to get it in terms of turn around for your patient – will ordering it help your tx decision or your patient
example of troponins versus CK-MB

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19
Q

Sequential versus concurrent ordering

A

Turnaround time for results important here
minimize # of tests ordered to promote efficiency and accuracy
Assess potential for patient risk

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20
Q

Single test versus profile/panel testing

A

Collection of different measurements related to specific organ system or disease
Useful in initial screening evaluation
IMPROPER use in continued monitoring

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21
Q

Is a Greater # of tests ordered always better?

A

NO

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22
Q

Long wait for results or high perceived risk for patient…….

A

need to order all of those, useful

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23
Q

When you need glucose measurement…

A

Order Chem 7

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24
Q

A proper use of STAT is an additional parameter that

A

expression of results
like
Qualitative–> absent or present
Semi-qualitative(PEESTICK)-> absent/trace/mod/marked
Quantitative(HCG)-> express in units of measurement, mass quantities; grams per deciliter, international units
Calculated-> direct measurement impractical- derived from math formulas using known values
LDL in lipid panel testing

25
Q

Lab tests are divided into categories of requests…

A

Routine tests are those for which blood samples are drawn or other body fluids are collected with no specific urgency. Doctors order these tests when the patient is not acutely ill and the results may be reported back to the doctor after a few hours to a few days time

26
Q

ASAP test request is ..

A

“as soon as possible”. This category is used when there is some urgency for the blood or body fluid to be taken and the test(s) to be performed. Examples might include such situations as a patient is in the waiting room for the results or the doctor is waiting for lab results before he orders medication for a patient.

27
Q

STAT test request is…

A

STAT stands for the Latin word “statim”, which means “with haste”. This category is used for tests that are urgently needed because the patient’s life or well-being is in danger. Examples of these types of orders might include typing and crossmatching blood for a patient in the emergency room who is bleeding from a gun shot wound.

28
Q

Prep-Op test request is…

A

Pre-op refers to those tests that are ordered before a patient is scheduled for surgery. Examples of these types of tests might include an H&H, which measures the amount of blood in a patient. A surgeon would not want to operate on a patient who is dangerously low on blood, since most operations involve blood loss.

29
Q

NPO test request is…

A

NPO comes from the Latin words “non per os”, which means “nothing by mouth”. These orders are for tests to be drawn before a patient eats. Many chemistry tests, including blood sugar and cholesterol, require that the patient be NPO or “fasting” before the blood is drawn.

30
Q

PP or PC test request is…

A

pp (or pc) means “post-prandial” or “after eating”. A few lab tests require that a patient have either eaten or drunk some type of food or sweet liquid and then have blood drawn a certain amount of time after that ingestion. An example is when a doctor wants to test a patient for diabetes; a patient is instructed to eat a full meal or drink a certain type of sweet liquid and have blood drawn two hours later. Diabetics will have a high blood sugar content after two hours while patients without diabetes will have a normal blood sugar after two hours.

31
Q

Results variability

A

Biologic variability- CANNOT BE CONTROLLED to reduce effect (gender, race, ethnicity)

Pre-analytic variability- Physiological influences that can be CONTROLLED. Like testing time-fasting state preferred. pre instructions & compliance, food intake, physical exercise, meds, smoking

32
Q

Pre-analytic Variability continued…

A
HUMAN ERROR...
Specimen collection and transport
IV lines, tourniquet
Handling of specimen during draw –mixing, hemolysis  (Potassium)
Storage and proper labeling
Time from draw to arrival in lab
Quantity Not Sufficient (QNS)
33
Q

Analytical Variability…

A

LAB ERROR ITSELF
Variability in lab measurement due to analytic method
Laboratory error versus clinician error
Performance of each contributes to total variability
Reagents, equipment, procedures, maintenance
Personnel
Specimen misidentification

34
Q

Test Characteristics

A

For confidence in medical decision making analytic test methods need to meet standards of statistical reliability
Accuracy and precision of each test established and monitored
WANT ACCURACY + PRECISION

35
Q

Accuracy

A

closeness or agreement of a measurement to its “true” value

36
Q

Precision

A

measurement of the reproducibility of a result (produce same value repeatedly)

37
Q

Quality Assurance

A

Maintenance of lab instrument and reagent variability
Confidence Interval- 95% perform within 2 standard deviations of the mean and 99% within 3 SD’s
Assess precision and accuracy of methods used

38
Q

Post analytical Variability…

A

Between completion of test and results reported
Transcription errors by various personnel
Timely reporting
Lab report form most reliable source

39
Q

How do you know theres a Lab Error?

A

Suspect when result is:
Unreasonable, unphysiologic or impossible
inconsistent with prior results
unexpected based on clinical picture
May require re-evaluation of clinical impression as well as confirmation of result
JUST REDRAW!

40
Q

Reference Ranges are normal values…

A
results interpreted relative to these
Determined relative to +/- 2SD of the mean of test result
normalized by age and gender
values vary depending on lab methods 
not same interpretation for all tests
41
Q

Critical/Panic values are..

A

DANGEROUS LEVEL

Immediate notification of results exceeding “critical limits”

42
Q

Calcium

A

8.4-10.2 mg/dL coma can occur if greater than 13.5 (panic value)

43
Q

Amylase 56-190 IU/L critical if greater than 3x the Upper Limit of Normal

A

TRUE

44
Q

In measures of diagnostic performace..

A

All tests ideally designed to help clinician discriminate between patient who has disorder and those who do not
“Gold standard” – all others compared to this
“Best” test available
Determine which test to use based on its measure of performance

45
Q

Sensitivity versus specificity

A

Sensitivity indicates how often false negatives will be encountered
Test 90% sensitive means 10% of the time results are falsely negative

Specificity indicates how often false positives will be encountered
Test 98% specific means 2% of the time results are falsely positive

46
Q

An ex of Use of test with high sensitivity followed by different test with high specificity

A

Serum amylase followed by serum lipase

47
Q

Sensitivity

A

Probability of a test to correctly identify those who truly HAVE the disease

True Positives-> reflects those individuals with particular disease who test POSITIVE to that test

False Negatives->reflects those individuals with the particular disease who test NEGATIVE to that test

48
Q

Specificity

A

Probability of a test to correctly identify those who truly DO NOT HAVE the disease

Known as True Negatives– reflects those individuals without particular disease who test NEGATIVE to that test

Indicates False positives- reflects those individuals without the particular disease who test POSITIVE to that test

49
Q

Example of sensitivity:

A
300 pts have an MI
CK-MB choice to indicate whether had MI
- 250 tested POSITIVE (TP)
-50 tested Negative (FN).. but we know had MI
sensitivity = 83% Neg
50
Q

Ex of specificity:

A
500 pts did not have MI
CK-MB choice to indicate
-10 tested Positive (FP)
- 490 tested Neg (TN)
98% specific
51
Q

SpPins

A

If a test used to RULE IN or CONFIRM a disease must have high specificity
- A positive result will rule in the disease
Specific PosIn(SpPin)

52
Q

SnNouts

A

If a test used to RULE OUT or EXCLUDE a disease must have high sensitivity
- A negative result will rule out the disease
SensitiveNegOut (SnNout)

53
Q

Predictive Values

A

Prevalence of a disease in a population or community -varies in different geographic locations or demographics

54
Q

Positive predictive value

A

likelihood that a positive test result will occur in those who have the disease

55
Q

Negative predictive value

A

likelihood a negative test result will occur in those who do not have the disease

56
Q

Likelihood ratios

A

Incorporates sensitivity and specificity of a test into a single measure
Ratio of probabilities for a given test
Likelihood a given test result would be expected in a patient with the disease compared to the likelihood the same result would be expected in a patient without the disease

57
Q

Medical diagnosis

A

diagnosis a clinical reasoning process relying on information from multiple sources- laboratory testing a component but not the only tool.

58
Q

Lab testing

A

a science conducted with statistical analysis standards and quality controls.