INTRODUCTION TO LABORATORY MEDICINE

DEFINITION

Laboratory medicine a specialty in which pathologists provide testing of patient samples (usually blood or urine) in several different areas.

Determination of the level of enzymes in blood in case of heart attack or

Level of glucose (sugar) in the blood of a patient with diabetes.

The presence of bacteria and other microorganisms.

Blood cells studies for various types of anemias

COURSE CONTENTS Clinical Biochemistry

Cardiac profilesLiver and renal panelsBone metabolismLipid chemistry

Special chemistryCardiovascular markersTumour markersNutritional markersCalculi

Immunology and ImmunodiagnosticsDrug monitoringUrine and serum proteinsAutoimmune disease testingEndocrinology testsFertility testing

Point-of-Care TestingCardiac markersGlucose monitoring programBlood gases and metabolitesRoutine chemistry panelsRoutine urinalysis and pregnancy screeningCoagulationComplete Blood Counts Urine toxicology screening

Laboratory Hematology Routine and special hematology

Hemoglobinopathy studiesSpecial stains

HematopathologyBone marrow consultations and

interpretive report Special coagulation

Coagulation profiles, screening and factors and inhibitors

Platelet studiesThrombophilia testing

Microbiology Infection control

Reference centre for medical microbiology and infectious diseases

Detection and typing of epidemiologically significant organisms

Molecular Diagnostic Testing Blood Bank/Donor Center

Concepts of immunohematology and histocompatibility

Blood transfusion services and quality assurance

Blood donation and storage of bloodBlood groupingCompatibility testing

RECOMMENDED BOOKS

Textbook:Clinical biochemistry an illustrated color

atlas by Allan GawDistrict laboratory practice in tropical

countries by Monica Cheesbrough.Clinical chemistry by William J Marshall.

Reference books:

Medical Laboratory technology by Ramnik Sood.

 

REASONS FOR ORDERING TESTS

Confirm diagnosis

Aid in diagnosis

Evaluate prognosis

Monitor therapy

Screen for a disease

SECTIONS OF THE LABORATORY CLINICAL PATHOLOGY

1. Clinical Chemistry  Liver profile Lipid profile Glucose profile

Special chemistry(endocrinology, fertility)

2.Clinical Microscopy  Analysis of body fluids Urin analysis Fecal anaysis Semen analysis

3. Microbiology  Cultures (sputum,blood, urine) Sensitivity tests4. Hematology Biggest section Includes CBC,coagulation,

PT, APTT 

Blood bankVery critical section 

Bec. May have errors Blood typing Cross match 

Goes hand in hand with serology and immunology

 Tests done for MALARIA SYPHILIS HIV

Serology/Immunology  Cardiac and thyroid fxntest

II. ANATOMY PATHOLOGY

Histopathology 

CIRCUIT DIAGRAM OF CLINICAL BIOCHEMISTRY PROCESS

SAMPLE

A sample of a material to be tested or analyzed 

that is prepared from a gross sample and retains the latter's composition.

SPECIMENS WHICH ARE USED IN LAB FOR TESTING Venous blood, serum or plsma. Arterial blood Capillary blood Urine Faeces Cerebrospinal fluid Sputum and saliva Tissue and cells Calculi Aspirates e.g.

Pleural fluid Ascites Synovial fluid Intestinal Pancreatic

NATURE OF REQUEST

STAT 

Performed immediately and by itself  

Run control and standard 

20-50% More expensive 

TAT is shortened  Request is needed

Today 

Confusing  Performed as

soon as possible, given priority

 Based on “running time”

Routine Done with the batch Wait for TAT stated

by laboratory

AUTOMATION AND COMPUTERIZATION

Test Repertoire (Range) More than 400 tests can be performed in the lab Analyzers

Laboratory personnels

VALUES

REFERENCE VALUES Better term than

“normal value” Pulled value, usually

95%of population Vary in diff. hospitals

but not that far

SIGNIFICANT VALUES Clinical decision

should be made if higher or lower than reference value

Usually when 2x to 3x

CRITICAL VALUES

Needs immediate attention “panic values” Should call physician Patient is at risk

Glucose less than 45mg/dl More than 500mg/dl Potassium less than 6.6 g/dl More than 19.9 g/dl

REFERENCE VALUES

Not fixed for allShould consider:

Age  Sex  Pregnancy  Diurnal Variation  Race  Blood type

ROUTINE EXAMINATIONS

ROUTINE ADMISSION TESTS CBC, Urinalysis, Fecalysis

ROUTINE CHEMISTRIES BUN, Creatinine, Glucose, Uric Acid, Cholesterol

  Sometimes triglycerides

SPECIMEN COLLECTION

Correct sample Correct information (history) More information is required while

reassessing or assessing prognosis. Identification must be clear and correct.

QUALITY ASSURANCE TO OBTAIN CORRECT TEST RESULTS

Immediate and long term clinical, public health, andhealth planning decisions are based on the results oflaboratory tests. Incorrect, delayed, or misinterpretedtest results can have serious consequences forpatients and communities, undermine confidence inthe service, and waste scarce district healthresources. Achieving reliability of test results is dependent on: Understanding what are the commonest causes of

inaccuracy and imprecision in the performance of tests and of delayed or misinterpreted

and sources of error). Taking the necessary steps to prevent and minimize errors by:

– implementing Standard Operating Procedures (SOPs) with quality control for all district laboratory activities.

– introducing every month a quality control day and an external quality assessment scheme for outreach laboratories (see later text, Role of the district medical officer in TQM).

– appointing a district laboratory coordinator to monitor the performance of district laboratories (see later text).

Agreeing with those requesting laboratory tests, policies of work that will enable the laboratory to provide an efficient, safe, cost-effective, and reliable service (see subunit 2.4).

Maintaining good communications between laboratory staff and those requesting tests.

REFERENCE RANGES FOR QUANTITATIVE TESTS