1- Intro Clinical Biochem
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Transcript of 1- Intro Clinical Biochem
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INTRODUCTIONTO CLINICAL
BIOCHEMISTRYLAB
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OBJECTIVE
Students are expected to:
Explain types of biochemistry test with examples.
Describe types of specimen available.
Understanding sources of sampling error. Explain the factors contributing variation of results.
Understanding the importance of the Clinicalbiochemistry lab.
Expecting General Risk
Describe Clinical Biochemistry Process
Elaborate Quality Assurance (QA) & Quality Control(QC)
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Types of Specimen
Blood
Serum- blood which is collected into plain tube that allowed toclot in room temp.
- recommended for biochemical analysis
Plasma- used when the analyte questioned is unstable- obtained when blood collected in an anticoagulant tube
- when centrifuged, the supernatant is called plasma
Urine Cerebrospinal fluid
Others?
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SPECIMEN COLLECTION The test request
The specimen for analysis must be collected andtransported to the laboratory according to a specified
procedure if the data are to be of clinical value. This
procedure begins with the clinician making a test
request, either on a computer terminal or on paper. Thecompleted request should include:
patient's name, sex and date of birth
hospital or other identification number
ward/clinic/address name of requesting doctor (telephone/pager number for
urgent requests)
clinical diagnosis/problem
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test(s) requested
type of specimen
date and time of sampling
relevant treatment (e.g. drugs).
It is essential that sufficient information be provided
to identify the patient. In practice, vital information is
often omitted and this may either cause delay in
analysis and reporting or make it impossible tointerpret the results.
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Sampling Error Blood sampling technique
-improper technique lead to hemolysis and give falsepositive result with consequent increase of potassiumand red cell constituents.
Prolong stasis during venipuncture- stasis causes plasma water diffuse into interstitialspace and serum or plasma sample obtained will beconcentrated.
- protein and protein bound components of plasma such
as calcium or thyroxine will be falsely elevated
Insufficient specimen
- certain volume of specimen is required to enable the
test to carried out
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Errors in timing
- collection of an accurately time volume of urine such as24 hrs urine
Incorrect specimen storage
- blood sample stored overnight before being sent to labwill show falsely high K+, phosphate and red cellenzymes such as LDH because of leakage into theextracellular fluid (ECF) from the cells.
Inappropriate sampling site
- blood taken downstream from IV drip may affected bythe drip content
Incorrect specimen container
-anticoagulant/ preservative. Eg: glucose in fluoride tubewhich inhibits glycolysis.
-never decanted into another tube.
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Variation Result
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Variation Result
Due to biological factors:
Gender-muscle mass
Age- increase in ALP
Diet-fasting,malnutrition,alcoholic
Pregnancy- insulin resistance
Time the sample taken- cortisol
Stress and anxiety
Medical and drug history
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Importance of Biochemistry Lab
Screening
detection of subclinical disease Diagnosisconfirmation or rejection of
clinical diagnosis
Prognosisinformation regarding the likely
outcome of disease
Monitoringmonitoring progression or
response to treatment
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General Risk in Lab Test
Determination of the right test
- to decide the most sensitive, specific, accurate andprecise with reasonable price
Sample collection procedure
- collected with right manner. Eg: avoid hemolysis duringblood collection
- collected from right source. Eg: CSF to determinemeningitis
Sample transportation- use the right tubes. Eg: tubes with sodium citrate forglucose
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Sample storage
- serum separated from blood cells before storage
- urine should not be left more than 2 hours unless
refrigerated
Human error
- unskilled lab personnel
Interpretation of result
- use the right reference range
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Clinical Biochemistry Process
Clinical questions
Request form & clinical data
Specimen collection
Transit sample to lab
Reception at lab and ID Analysis
QC
Collation
Result interpretation Reporting to doctor
Biochemistry answer
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Quality Assurance (QA) & Quality
Control (QC)
Pre Analytical Quality Assurance
Analytical Quality Assurance
Post Analytical Quality Assurance
Quality Control
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Quality Assurance (QA)
QA - all activities that ensure the validity ofchemical testing and analysis and all relevant
technical support
Lab personnel required to follow QA plans and
SOP
These documents and staff vigilance help
ensure the analytical data and other test results
will be acceptable as the bases for makingsignificant decision.
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Pre Analytical Error
Patient preparation- nutrition status, recent meal, alcohol, drugs, smoking,exercise, stress
Sample collection and handling
- right specimen collection tubes usage
- sample match with anticoagulant or additive
- specimen transportation and separation
- avoid contamination
-effects of infusion
- hemolysis
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Storage
- to know the characteristics of each analyte and store
with right manner in order to preserve the analyteamount
- Evaporated analyte to store with tightly capped. Eg:
electrolytes
- Light sensitive analyte to be stored in dark place. Eg:bilirubin
- Temperature sensitive analyte to be refrigerated. Eg:
Lactate dehydrogenase
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Post Analytical QA
System to record all patients profile to avoidlosing data
System to report the reliable lab data to the
doctors in specific time given
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Quality Control (QC)
Refers to the measures that must be included
during each test run to verify that the test is
working properly.
Aims to recognize and minimize analyticalerrors.
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Management requirement ISO 9000
-certification:
-documented quality system is in place
-Auditors are skilled in Quality Assurance but
may not have the expertise in service.
ISO 15189
-more specific for lab operation
-technically competant, have laboratory
experience, skilled in lab management, QA
technique
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ANALYSIS OF BLOOD
BIOCHEMISTRY
http://rds.yahoo.com/_ylt=A0S020yS4UhKgOYA8lijzbkF/SIG=12lpglmue/EXP=1246376722/**http%3A//www.sandhurstjoggers.org.uk/3-HealthAdvice/blood_cells.jpg -
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Learning objectives:
Describe blood composition
Differentiate types of blood sample and its
source
Explain causes lead to hemolysis and how to
avoid hemolysis
Identify the blood collection tubes and the
usage of the tubes
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Blood Composition
Cells
Erythrocytes
Leucocytes
Platelet
Plasma vs serum?? - nutrient, metabolism
product
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Plasma vs serum
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Hemolysis Due to - high speed centrifugation
- high pressure during draw the blood
Hemolysis avoided by: Use dry and clean needle and syringe
Apply minimal constriction on arm
Let blood flow slowly into syringe
Use dry blood tube Mix well blood with anticoagulant
Low velocity centrifugation
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Blood Tubes
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St Additi R lti Additi A C t
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Stopper
Colour
Additive Resulting
Sample
Additive
Action
Assay Comments
Grey Na fluoride &
K oxalate
Plasma Inhibit
glycolysis
Glucose,
lactose
Not for Na & K
analysis
Green Na/Li/NH3
Heparin salts
Plasma Enhance
antithrombin
III
Cortico
steroids,
electrolytes
Antithrombin
III inactivates
clotting factors
Brown Na heparin Plasma Enhance
antithrombin
III
Lead Tube has only
minute
quantity of
lead
Royal
blue
None Serum None Trace
elements
Tube has only
minute
quantity of
traceelements
Lavender EDTA Plasma Binds Ca CEA,
hematology
test
Ca is needed
for clotting
Blue Na citrate Plasma Binds Ca Coagulationtest Ca is neededfor clotting
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NEXT CLASS
ACTIVITY 1
Student need to form group of 4 and number
each group member. Propose a procedure on
drawing blood sample and decide on the best
tube used for these situations: a) To monitor blood glucose level
b) To investigate bleeding tendency
c) To determine cardiac enzyme level in
blood
Justify your answer.