INTRODUCTION ,COURSE OVER VIEW

MLS Level 7

Ms.Elham Ali Saad

Objectives • Discuss different type of patient’s sample

• Define&Explain substance of clinical interest in many different

situation

• List Component of each test ?

• Compare between different Types of results obtained in the

laboratories

• Compare between different Types of tests in clinical laboratories?

• Describe different Types of equipment & instruments are used in

clinical laboratories

• Discuss Important consideration in using tests, equipment's &

instruments

Function of the clinical lab

• Carry out analysis and investigations on patient’s

samples upon to request of the doctor to obtain

meaningful and timely results which will help the doctor

in the proper diagnosis , treatment and management of

the patient condition .

• The patient sample can be any type of

material obtained from the patient

which include;

-Whole blood -plasma -serum

-CSF -synovial fluid

-Amniotic fluid -saliva -pericardial fluid

-sweat -sputum -plural fluid

-peritoneal fluid -semen -body swabs

-urine -Body tissues (biopsies and

needle aspirations)

• Substances of clinical interest are those which are

affected directly or indirectly by the disease.

• The effect of disease on such substances can be

increase , decrease or presence of the substance

• Components of tests:

patients sample+ specific reagents+ means of identification

• Substances of clinical interest that may be increased

or decreased due to disease include;

-RBC -WBC -platelets -Hb -Hct -PT

-PTT -Na -K -Cl -Ca -Mg

-PO2 -PCO2 -glucose -protein -albumin

-γ-globulin (IgG , IgM , IgA)

-Enzymes (ALP , AST , ALT , GGT….)

-Ammonia -urea -creatinine -cholesterol -TG

-Hormones (cortisol , aldosterone , GH ,T3 , T4 , PTH….)

• Substances of clinical interest that their presence

may indicate the presence of disease include;

-Bacteria -Parasites -Viruses

-Tumor Markers (AFP , CEA , PSA…)

-Abnormal cells or tissues

• Reagents of the test include:

-Diluent (H2o , 0.9%NaCl , other solutions)

-Solvents (ethanol, acetone, iso-butanol,

petroleum ether , other organic and aqueous

solvents)

-Dyes (giemsa stain, wright stain, BCG,

hemotoxylin, gram stain , malachite green…)

-Buffer : are used when the reaction required

specific pH (acidic , neutral or alkaline pH)

-Catalysts :

Used to lower the energy requirement for the progress of

the reaction and speed up the reaction

It can be chemicals or substances such as : (Mg, Ag, Urea ,

Caffeine)

They can be also biological (i.e. enzymes) such as

(dehydrogenases , oxidases , reducates)

-Reaction solution:

Are chemicals which are prepared at specified

concentration with specific procedure.

They could be just one single compound (AgCl ,HClO4

, H2O2)

In many cases , the reaction solutions involve two or

more compounds which are added in one step (e.g.:

biuret reagent (protein) , jaffe-reagent (creatinine)

Types of results obtained in the laboratories

Types of tests1- Screening tests:

Characteristic Simple test

Cheap to perform

involve 1 single step;(mixing 1 drop of

sample + 1 drop of reagent = formation of

product by visual means (naked ye or light

microscope).

Aim of this type

applied to screen for the presence or

absence of specific disease or disorder

Place to performed

outside the lab or hospital

Requirements

Require minimum amounts of reagents and

equipment's

Don’t require high technical skills

Results

quickly and clearly obtained

Results can be easily interrupted

either qualitative or semi-quantitative

Results obtained are +ve results must be

confirmed by further more and accurate

specific results.

2- Confirmatory Tests:

Characteristic More complex and number of steps

Tests are more sensitive and specific

than screening test

Aim of this type Are used to confirm the positive results

obtained from screening test

Requirements

Require specialized equipments and

instruments

Are performed in the lab

Require technical skills and experience

Results

Results more accurate and precise than

screening test

Results can be qualitative , semi-quantitative

or quantitative

If the results is also +ve then the patient is

referred for medical examination

If the results is negative , then the disease or

disorder is ruled out (no disease)

3- Diagnostic tests:

Characteristic expensive and technically demanding

not necessary confirmatory tests but

confirmatory test may be diagnostic

Examples:

- High level of amylase in both blood and urine are

diagnostic for acute pancereatitis

- High level of HCG in women is diagnostoc for

pregnancy

- High level of urea and creatinine are diagnostic foe

renal abnormality

- Low level of cortisol in blood is diagnostic for

addison’s disease

- High level of glucose in GTT are diagnostic for diabetes

mellitus

Place of performed

Usually performed in the lab

Aim of this type

check for specific substances which are

indicative for the presence of disease or

disorder.

Requirements

Require skill , experience, and good

background of pathophysiology of the disease

Require instruments and equipments of high

accuracy and precision

Require tests with high sensitivity and

specificity

Results Can be qualitative , semi-quantitative or

quantitative

In quantitative and semi-quantitative results

the severity of the disease may be related

to the level of the substance

4- Definitive test:

Characteristics Highly advanced, specialized and complex procedures

They include ; PCR , Mass-spectroscopy ,

HPLC , GC

Aim of this type

1-Detection of inherited disorder such as; a.a

metabolism abnormalities, f.a metabolism

abnormalities, cystic fibrosis , muscular

dystrophy ,coagulation abnormalities , Hb

abnormalities and many other.

2-It is also being applied to detect the presence

of viruses , bacteria and other microorganisms

Aim of this type

3-detect the presence of specific causative

agents such as ; genes , gene mutations ,

specific metabolites or specific cells

This type of tests are able to show disease

variations

Requirements

high level of technical skill , good

experience and background on advanced

techniques

high complex and advanced instruments and

equipments

Results Usually qualitative

Types of equipments and instruments are used in clinical

laboratoriesA)Basic equipments :

Example

- Pipette -Glassware

- -Plastic ware

-Mixer -Balances

-Fridge -Safety cabinet

-Freezer -Fume-cupboard

-Centrifuge

B)Single application instruments:

-Example:

light microscope -spectrophotometer

single channel counter

single test analyzers (PH Pco2,Po2 , Na, K , Cl, Hb-

meter)

-Can be linked to computer for operations and results

-Very important in high capacity(large) laboratory

-Reduce the amount of time ,effort and

space required for tests.

-Example

1-automated hematology analyzer :

measure RBCs , WBCs ,platelets , Hb,

Differential , Hct , and calculate MCV ,

MCHC)

2-automated chemistry analyzer(measure

number of analytes

C) Multi-tests (multi-sample instruments):

-usually fully or partially automated

-Can carry out more than one measurements

-Can process many samples

-Depend on electronic and computer controls

-Combine various technique and instruments in one large

system as :

(pipetting+spectrophotometer+ISE+incubator+mixer+

Washing + centrifugation+calculation)

Important consideration in using tests , equipment's & instruments

-title/name -purpose and aim

-principle of operation the instruments

-principle of test -proper methodology

-reagent preparation -type of specimen

-collection and handling of specimen

-transportation

-processing and storage of specimen

-precaution and source of errors

-safety consideration(electrical, fire,biological,chemical ,waste)

-use of standards , calibrators and controls

-results calculation and interpretation

-installation and maintenance of instruments

-sensitivity and specificity ,accuracy and precision of test

and instruments .

-updating/changing of tests and instruments

-always time manage and organize your procedures and

instruments

THANK YOU