INTRODUCTION TO CLINICAL BIOCHEMISTRY

DR. MD. MAHBUBUR RAHMAN MBBS, M. Phil MSc. (Biotechnology)

DEPT. OF BIOCHEMISTRY

RAJSHAHI MEDICAL COLLEGE

After the end of the session student will able to know the

• Definition of Clinical Biochemistry

• Core and Emergency Biochemical Test

• Colorimeters and its principle

• Electrophoresis technique

• Characteristics of Good laboratory

Definition of Clinical Biochemistry

Is that branch of laboratory medicine in which

Chemical and Biochemical methods are

applied to study the disease.

Use of Biochemical Test

• To diagnosis the disease

• To monitoring the treatment

• Screening for disease

• In assessing the prognosis of disease

Core Biochemistry

• Most the Biochemistry laboratories provide the

commonly requested test which are of value of

many patient is known as Core Biochemical test.

Core Biochemical test are:

• Sodium, Potassium,Chloride& Bicarbonate

• Urea and Creatinine

• Calcium and Phosphate

• Total protein and Albumin

• Bilirubin and alkaline Phosphatase

• Alanine aminotransferase (ALT) & Aspartate

Aminotransferase (ALT)

• Thyroxin & TSH

• ɣ GT ( Gamma glutamyl transpeptidase)

• Creatin kinase

• Glucose and amylase

Core Biochemistry

Emergency Test

• Urea and Electrolytes

• Blood Gases

• Amylase

• Glucose

• Salicylates

• Paracetamol

• Calcium

Specialised Test

• Hormones

• Specific Proteins

• Trace elements

• Vitamins

• Drugs

• Lipids and Lipoproteins

• DNA analysis

PHOTOMETRY

• Is the study of measurement of light.

• Spectrophotometry is defined as the measurement

of the intensity of light at selected wavelength

Beer’s Law

States that the concentration of substances is

directly proportional to the amount of light

absorbed or inversely proportional to the

logarithm of transmitted light. This law

expressed as

A= abc

Where A indicate Absorbance, a indicate

proportionality constant defined as

absorptivity, b indicate light path in cm, c

indicate concentration of absorbing compound

usually expressed in gm per litre.

Beer’s Law

Lambert’s Law

When a monochromatic light is passing through a

solution, the intensity of light transmitted decreases

exponentially with increasing path length.

Absorbance

The amount of light absorbed by the color of

solution is known as absorbance.

Instrument use to read absorbance

• Filter photometer / Colorimeter (Use filter)

• Sprectrophotometer ( Use prism or grattings)

–Single beam sprectophotometer

–Double beam sprectophotometer

Colorimeter

Is the instrument that is used to measure color of a

solution.

or

Is used to measure the concentration of a substance in

a patient’s sample by comparing the amount of light it

absorbs with that absorbed by a standard preparation

that contains a known amount of the substances being

tested.

Component of colorimeter

• A light source

• A means to isolate light of desired

wavelength ( filter or monochromator)

• Fiber optic

• Cuvet

• A photodetector

• A reader device

• A microprocessor

Component

light entrance Filter Exit Cuvet Detector Meter

source slit slit

Difference between colorimeter and spectrophometer

Colorimeter Spectrophometer

Use filter Use prism or grattings

Only visible light can be measured

Beyond the visible light can be measured

Result is less accurate Result is more accurate

Calculation

Concentration of test

=Absorbance of test

Absorbance of standard X Concentration of Standard

Test done By colorimeter

• Blood glucose

• Serum Creatinine

• Serum Cholesterol

• Serum TG

• Serum Bilirubin

• ALT & AST

Sample used in Biochemistry

• Blood

• Urine

• Feces

• Spinal fluid

• Synovial fluid

• Amniotic fluid ( Amniocentesis)

• Pleural /Pericardial and ascitic fluid

• Saliva

• Swabs

• Solid Tissue: Malignant tissue from breast for

estrogen and progesteron

• Hair and finger nail: have been used to detect

trace metal.

Sample used in Biochemistry

Electrophoresis

Is a comprehensive term that refers to the

migration of charged solutes or particle of any

size in a liquid media under the influence of

electric field.

Types of Electrophoresis

• Slab gel Electrophoresis

• Disc Electrophoresis

• Isoelectric Electrophoresis

• Isotachophoresis

• Pulse field Electrophoresis

• Two dimensional Electrophoresis

• Capillary Electrophoresis

• Microchip Electrophoresis

DEFINITION OF ACCURACY

Accuracy is defined as closeness of agreement between

the test result and the accepted true value.

Accuracy defines how close the measured value is to

the actual value

DEFINITION OF ACCURACY

Agreement between the best estimate of a quantity

and its true value.

DEFINITION OF PRECISION

• Precision is the reproducibility of analytical method.

• Precision is a measure of reproducibility.

• Agreement between replicate measurement.

DEFINITION OF SENSITIVITY

• Sensitivity of an assay is measure how little analyte

that can detect by the assay.

• Sensitivity of an assay is measure that can able to

detect the lowest amount of the analyte by the assay.

• The ability of an analytical method to detect the small

quantities of the measured component

SPECIFICITY

• Specificity of an assay relates how good the assay is

at discriminating between the requested analytes

and surrounding interfering substances.

• The ability of an analytical method to determine

solely the components it purports to measure.

QUALITY ASSURANCE

QA has been summerised as the :

Right result, at the

Right time, on the

Right specimen, from the

Right patient with result interpretation based on

correct reference data, and at the

Right price.

QUALITY CONTROL

• The term quality control covers that part quality

assurance which primarily concerns the control of

errors in the performance of test and performance

of test results.

SI unit

The International system of unit has been

developed and agreed internationally in 1960.

.

It overcomes language barriers, enabling an

exchange of health information within a

country and between nations to be made

without the misunderstanding which arise

when each country or even a separate hospital

within a country uses its own units of

measurement for reporting tests

SI unit

CLASSIFICATION OF SI UNIT

• SI BASE UNIT

• SI DERIVED UNIT

• SI PREFIXES

SI BASE UNIT

The international system of Units is based on the

meter-kilogram- Second system and replaces both

the foot-pound-second system and centimeter-

gram-second system.

SI BASE UNIT

SI base unit Symbol Quantity measure

Meter m Length

Kilogram Kg Mass

Second S Time

Mole Mol Amount of substance

Ampere A Electric current

Kelvin K Temperature

Candela Cd Luminous intensity

SI DERIVED UNIT

SI derived unit Symbol Quantity measure

Square meter m2 Area

Cubic meter m3 Volume

Meter per second m/s Speed

• SI derived units consist of combinations of base units.

SI PREFIXES

• To enable the measurement of quantities larger or

smaller than the base units or derived units the SI

unit system also includes a set of prefix a unit

larger or smaller.

• example: micro, nano, pico femto

Conversion of conventional unit to SI unit

mg/dl x 10

mmol/L =

Molecular wt of substances

Molecular wt

Glucose --—180

Creatinine ----113

Cholesterol--- 386

Bilirubin ----- 584

Urea-----------60

Different SI unit

• SI unit of

– Glucose – mmol/ L

– Urea--- mol/ L

– Creatinine-- µ mol/L

– Bilirubin ---µ mol/L

– Albumin gm/L

»Thank You