Clinical Biochemistry PLC 402

• Clinical Biochemistry is course PLC 402
• Prof. Hend Hussein and Ass. Prof. Inas Masoud are course lecturers
• Ass. Lect. Sara El-Hadey is a course assistant
• The clinical biochemistry course provides advanced knowledge of body chemistry under healthy and abnormal conditions
• The course evaluates clinical specimen suitability and lab test outcomes
• The course explains the relation between diseases and blood chemistry abnormalities

Course Description

• Clinical Biochemistry (PLD 402) involves the study of sampling techniques, analysis of chemical components, plasma proteins, and kidney and liver function
• The course includes the study of body electrolytes, acid-base balance, hormones, and disorders in thyroid function

Course Content

• The course content includes:
  • Blood Sampling
  • Acid-Base balance
  • Electrolytes
  • Kidney Function
  • Acute Phase Protein
  • Hormones
  • Diabetes Mellitus
  • Liver Function
  • Cardiac Function
  • Tumor Markers
  • Thyroid function

Blood Samples

• Blood samples can be used to:
  • Diagnose diseases
  • Screen for risk factors
  • Monitor the effects of treatments and medications
• Blood samples are usually obtained from a patient's vein
• Specialized blood tests, like blood gases, require blood arteries
• Blood gas analysis monitors CO2, O2, blood pH, and bicarbonate levels related to pulmonary function or metabolic conditions

Laboratory Analysis Types

• Biochemical analysis
• Molecular analysis
• Cellular analysis

Biochemical Analysis

• Biochemical analysis includes testing levels of:
  • Sodium
  • Potassium
  • Chloride
  • Calcium
  • Phosphate
  • Magnesium
  • Iron
  • Urea
  • Creatinine
  • Liver enzymes
  • Copper
  • Zinc
  • Glucose
  • Cholesterol
  • Bicarbonate
  • Lactate
• And others

Molecular Analysis

• Molecular analysis includes:
  • Protein electrophoresis
  • RNA
  • DNA
• DNA testing, via PCR technique, is used in diagnoses and forensic sciences

Cellular Analysis

• Cellular analysis includes:
  • Complete blood count (CBC)
  • Erythrocytes sedimentation rate (ESR)
  • Cross-matching for blood transfusion or transplantation
  • Blood culture

Precautions

• Universal precautions should be used to increase the safety of blood collection
• Using precautions reduces the risk of exposure to infectious materials
• Protective barriers include:
  • Gloves
  • Masks
  • Gowns
  • Eyewear
• Universal precautions protect against the transmission of HCV, HBV, HIV, and other blood pathogens
• Universal precautions are applied in:
  • Blood
  • Semen
  • Vaginal secretions
  • Pleural fluids
  • Cerebrospinal
  • Synovial
  • Peritoneal
  • Pericardial
  • Amniotic fluids
  • Tissues

Unacceptable Sites for Blood Drawing

• Avoid drawing blood from:
  • An arm affected by a stroke or neurological injury
  • The arm of a mastectomy patient
  • Areas with extensive scar tissue, shunts, varicose veins, or the palm
  • The arm of a patient that receives intravenous fluids
  • Sites that are swollen or affected by certain skin conditions like eczema or other infection

Patient Information Before Blood Draw

• You should ask the patient about factors that may affect test results:
  • Medications
  • Pregnancy
  • Age
• Make sure the patient has followed special test instructions such as fasting or taking medication

Patient Preparation

• Instruct the patient about the ordered blood tests and the reason for the tests
• Ask the patient if they have had trouble during blood draws in the past
• Ask the patient what position would be most comfortable for them during the specimen draw
• Venipuncture makes many patients nervous, encourage them to lie down

Personnel Responsible for Blood Drawing

• People responsible for blood extraction:
  • Physician
  • Pharmacists
  • Technicians
  • Practitioners
  • Paramedics
  • Phlebotomists
  • Nurses staff
  • Respiratory therapists

Equipment for Sample Drawing

• Equipment needed for sample drawing:
  • Vacutainer needles
  • Syringes
  • Butterfly needles
  • Antiseptic 70% alcohol wipes or disinfection swabs
  • Tubes
  • Vacutainer holder
  • Tourniquet for finding a vein
  • Adhesive dressing
  • Rubber gloves
  • Pillow or other support
  • Sharps disposal container
  • Disposal box

Vacuum Tubes

• Vacuum tubes are designed to draw a determined volume of blood
• The blood draw system includes:
  • Vacuumed specimen tubes
  • A needle
  • A plastic holder
• When tubes are placed into the holder, a negative pressure results, and blood is pulled into the tube

Equipment for Handling, Transfer and Storage

• Equipment for handling, transfer, and storage:
  • Transfer and storage tubes
  • Pipettes
  • Centrifuge
  • Racks for tubes
  • Special boxes for tube transfer and storage
  • Freezer for storage

Blood Extraction Methods

• Venipuncture: Useful to obtain cells and extracellular fluids (plasma or serum) for analysis
• Fingerstick: Used if only a few drops of blood are needed
  • Example: blood group testing
• Heel-stick: Preferred method of blood collection on a newborn baby or infant

How to Carry Out a Blood Test

• During blood collection, the arm should rest on a pillow or other support
• The patient opens and closes their fist
• The phlebotomist applies the tourniquet around the upper arm
• Inspect and palpate to find a proper vein
• Sterilize the injection site
• Minimize tourniquet use to avoid hemoconcentration
• The needle should be beveled upwards when pushed smoothly and quickly into the vein
• The smooth and quick motion minimizes the possibility of hemolysis from vascular damage
• Release the tourniquet immediately after insertion to minimize the effect of hemoconcentration
• The needle is attached to a low-pressure blood test bottle (Vacutainer) or a syringe where the plunger is pulled back to create low pressure
• Once the necessary amount of blood has been extracted, the needle is removed
• A little ball of cotton wool is held over the wound for 1 minute
• Artery blood is extracted from the wrist where the artery is close to the skin
• Hold a ball of cotton wool over the wound for 5 minutes after arterial draw, to stop bleeding

Tubes for Specimen Collection

• Blood collection tubes come with various colored stopper caps, and may contain additives
• The colored stopper is important to avoid the cross-contamination of additives between tubes

The Tubes Additives

• A Serum separator tube (SST) contains a polymer gel used for blood chemistry (Glucose, urea, cholesterol, Na, K, Mg, Zn)
• Heparin tubes (green top tubes) are used for lithium and ammonia levels
• EDTA tubes (with lavender tops) are used for complete blood counts
• Sodium citrate tubes (light blue tops) are used for prothrombin time (PT) and partial prothrombin time (PTT) analysis
• Sodium fluoride preserves glucose for up to five days
• Sodium fluoride tubes are used primarily to obtain glucose levels
• Free anticoagulants or additives can be used for blood typing and cross-matching
• Blood culture tubes have a Yellow-black stopper

Safety Remarks in The Lab

• The lab does not allow eating
• Tables should be kept clean and wiped with sterilizing agents
• Wash hands in running water before and after blood collection
• Gloves should be used in blood drawing and handling
• Dispose of needles in a sharps container

Safety Actions After Needle Stick Injuries

• Actions to take if you have a needle stick injury:
  • Don't panic
  • Clean the infected area
  • Rinse with water
  • Wash with antibacterial soap
  • Squeeze the wounded area
  • Place 70% alcohol on the wound for two minutes
  • Contact the local health professional responsible for infectious diseases

Quality Control of Laboratory Analyses

Internal Quality Control

• Each laboratory system should have quality control materials
• Secondary calibrators are applied according to an internationally recognized reference method
• Each standard (calibrator) should be run at least in duplicate

External Quality Control

• External quality control is arranged by internationally recognized reference laboratories that distribute batches of samples of various concentrations for each assay
• The participating laboratory is blinded to the concentration of the analyte
• Standard deviations of the results of the participating laboratory serve to measure performance

Why Analytical Results Vary

Individual Analytical Variation

Inter-individual variation

• Age
• Sex
• Race
• Genetics

Intra-individual variation

• Diet
• Drugs
• Sleep pattern
• Situation or Position

Laboratory Analytical Variation

Pre-analytical variation

• Transport delays
• Exposure to UV light
• Standing time before separation of cells
• Centrifugation time
• Storage conditions

Analytical variation

• Random errors
• Systematic errors

Post-analytical variation

• Transcriptions errors
• Giving the result report to the wrong patient

Hemolysis

• Hemolysis (rupture of red blood cells) can cause significant changes in some analytes such as:
  • Potassium
  • Magnesium
  • Sodium
• Released hemoglobin can interfere with colorimetric assays
• Lipemia (lots of fats) and proteinemia (lots of proteins) cause serum/plasma to become turbid
• Turbidity can affect colorimetric and turbidimetric-based tests (giving false results)