LESSON 1: INTRODUCTION TO CLINICAL CHEMISTRY 1

Clinical Chemistry

Is a quantitative science that is concerned with the measurement of amounts of biologically important substances (called ANALYTES) in body fluids.

Clinical Chemistry (Other textbook definition)

A biochemical analysis of our body fluids to detect any analytes that you wish to study or measure in support of the diagnosis and treatment of certain diseases.

Clinical Chemistry (Branch of medicine)

The branch of laboratory medicine that focuses primarily on molecules.

Father of Clinical Chemistry (Austrian Chemist)

Johann Heller

Scope of Clinical Chemistry Research

Analyzing the chemical composition of the human body.

Primary Purpose of a Clinical Chemistry Laboratory

To facilitate the correct performance of analytic procedures that yield accurate and precise information thereby aiding patient diagnosis and treatment.

Reliable results requirement

The achievement of reliable results requires that the clinical laboratories scientist must be able correctly use basic supplies and equipment and possess an understanding of fundamental concepts critical to any analytic procedures.

Clinical Chemistry Progress

CLINICAL CHEMISTRY continues to be one of the most rapidly advancing areas of laboratory medicine.

Improvement in Clinical Chemistry Laboratories

With the advancement of clinical laboratories worldwide, it is expected that the medical technologists would deliver/improve the quality of patient care by releasing accurate and precise results for the diagnosis and treatment of diseases.

Commercial Kits commonly used in today’s clinical laboratories

1. Package inserts;

2. Instrument manuals;

3. Kit package inserts

Reagents

Substances that are employed to produce a chemical reaction when coupled with other substances. They are an integral part of any chemical reaction.

Forms of Reagents

Liquid, Dry, Cartridge, Strip

Manual Methods (Testing)

Means making the reagents and performing the test by hand.

Disadvantages of Manual Methods

• Slow or time-consuming;

• Labor intensive;

• Often not precise.

Automation (Common Benefits)

• Increased numbers of tests performed by one technologist in a given time period;

• Labor decrease;

• Minimized variation in results between technologists due to slight variations in technique;

• Increased variety of techniques or tests being offered;

• Improved patient care as a result.

Analytical Chemistry

Studies and uses instruments and methods to separate, identify, and quantify matter.

Analytical Chemistry (In practice)

The separation, identification, and quantification may constitute the entire analysis or become combined with another method.

Qualitative Analysis

Means that the analyte must be identified.

Quantitative Analysis

Determines the numerical amount or concentration of that certain analyte.

Biochemistry

• Otherwise known as Biologic Chemistry/ Biological Chemistry;

• Study of chemical processes within and relating to living organisms.

Biochemistry Subdiscipline

Chemistry and Biology.

Fields of Biochemistry

Structural biology, Enzymology, Metabolism.

Endocrinology

Branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions known as “hormones”.

Endocrinology (Scope)

Concerned with the integration of developmental events such as proliferation, growth, differentiation, psychological or behavioral activities of metabolism, growth and development, tissue function, sleep, digestion, respiration, excretion, mood, stress, lactation, movement, reproduction, and sensory perception caused by our hormones.

Instrumentation

A collective term for measuring instruments and is used for indicating, measuring, and recording physical quantities.

Instrumentation (Field of study)

A field of study about the art and science of making measurement instruments involving the related areas of automation.

Instrumentation (Origin)

The term has its origins in the art and science of scientific instrument making.

Instrumentation (Application)

It can refer to devices as simple as direct reading thermometers at home, or as complex as multisensory components for clinical chemistry analyte-measuring devices.

Toxicology

Scientific discipline which overlaps with Biology, Chemistry, Pharmacology, and Medicine that involves the study of adverse effects of chemical substances on living organisms.

Toxicology (Practice)

It is also the practice of diagnosing and treating exposure to toxins and toxicants.

Toxicology (Dose relationship)

The relationship between dose and its effect on the exposed organism is of high significance in Toxicology.

Toxicology (Research contribution)

It is currently contributing to the field of cancer research because some toxins can be used as drugs for killing tumor cells.

Common Analytes Measured in the Clinical Chemistry Laboratory – Ions & Salts

• Carbonate,

• Acetate,

• Ammonium,

• Nitrate,

• Nitrite,

• Sodium chloride,

• Potassium dichromate.

Common Analytes Measured – Minerals

• Calcium,

• Iodine,

• Magnesium,

• Phosphorus,

• Sodium,

• Zinc.

Small Organic Molecules

• Glucose (for sugar/carbohydrates),

• Cholesterol (for lipids),

• Stearic acid (for fatty acid).

Large Macromolecules (4 main types)

• Carbohydrates,

• Nucleic acids,

• Proteins,

• Lipids.

Large Macromolecules – Transport Proteins

• Albumin,

• Transferrin,

• Haptoglobin,

• Ferritin,

• Total Protein.

Large Macromolecules – Enzymes

• Lipase,

• Amylase,

• Alanine aminotransferase (ALT),

• Aspartate aminotransferase (AST),

• Alkaline phosphatase (AlkP),

• Lactate Dehydrogenase (LD),

• Creatine kinase (CK).

Large Macromolecules – Specific Proteins

• Immunoglobulins (IgA, IgG, IgM),

• Complement C3,

• Complement C4,

• C-reactive protein (CRP).

Large Macromolecules – Lipoproteins & Diabetes Marker

• High density lipoprotein (HDL),

• Low density lipoprotein (LDL),

• Lipoprotein (a),

• Hemoglobin A1c (HbA1c).

Electrolyte Panel

• Sodium (Na),

• Potassium (K),

• Chloride (Cl),

• Carbon dioxide (CO2).

Hepatic Panel (Liver Profile)

• Albumin,

• Total Protein,

• Alkaline phosphatase,

• Alanine aminotransferase (ALT),

• Aspartate aminotransferase (AST),

• Total bilirubin,

• Direct bilirubin.

Comprehensive Metabolic Profile

• Sodium (Na),

• Potassium (K),

• Chloride (Cl),

• Carbon dioxide (CO2),

• Glucose,

• Creatinine,

• Urea,

• Calcium,

• Total Protein,

• Albumin,

• Alanine aminotransferase (ALT),

• Aspartate aminotransferase (AST),

• Alkaline phosphatase,

• Total bilirubin.

Basic Metabolic Panel

• Sodium (Na),

• Potassium (K),

• Chloride (Cl),

• Carbon dioxide (CO2),

• Glucose,

• Creatinine,

• Chloride (Cl),

• Urea (Blood Urea Nitrogen; BUN).

Lipid Profile

• Total cholesterol,

• LDL cholesterol,

• HDL cholesterol,

• Triglycerides.

Biological Specimens acceptable in the Clinical Chemistry Department

• Blood,

• Urine,

• Cerebrospinal fluid (CSF),

• Amniotic fluid,

• Synovial fluid,

• Pleural fluid,

• Peritoneal fluid,

• Pericardial fluid,

• Others.

Blood

The most common biologic fluid collected for clinical laboratory testing.

Blood (Two Main Parts)

Fluid Portion and Cellular Portion

Fluid Portion

Plasma (anticoagulated blood) containing dissolved ions and molecules.

Cellular Portion

Made up of the red blood cells, white blood cells, and platelets.

Plasma

• Centrifugation done directly with anticoagulants.

• Clotting factors present (e.g. Fibrinogen).

• Is the main component of blood, consists mostly of water with proteins, ions, nutrients, and wastes mixed in.

Serum

• Centrifugation done after coagulation without anticoagulants.

• CF absent. Serum = Plasma – CF.

• Usually used for diagnosis.

Plasma vs Serum (Key Point)

With anticoagulant = Plasma. Without anticoagulant = Serum.

Urine

Especially suitable for tests that evaluate kidney functions, tests that look at waste products excreted by the kidneys, and for metabolites that are cleared quickly from the bloodstream and accumulate in the urine, such as drug of abuse (DOA).

Urine (Other tests)

• Creatinine clearance measurements (makes use of 24-hour urine).

• Proteins and/or glucose (to know if there is already a certain amount of damage in the kidneys).

Random Specimen

No specific time, most common, taken any time of the day.

Random Specimen purpose

Routine screening, Chemical, FEME.

Morning Sample

First urine in the morning. Most concentrated.

Morning Sample (purpose)

Pregnancy test, Microscopic test.

Clean-Catch Midstream

Discard first few mL, collect the rest.

Clean-Catch Midstream (Purpose)

Culture

24-Hour Urine Sample

All the urine passed during the day and night and next day 1st sample is collected.

24-Hour Urine Sample (purpose)

Quantitative and qualitative analysis of substances.

Postprandial Sample

2 hours after meal.

Postprandial Sample (purpose)

Determine glucose in diabetic monitoring.

Suprapubic Aspiration

Needle aspiration.

Suprapubic Aspiration (purpose)

Obtaining sterile urine.

Amniotic Fluid

A clear to slightly yellow liquid that cushions the fetus within the amniotic sac. The developing fetus floats in the amniotic fluid for the entire duration of the pregnancy.

Amniocentesis (Indications)

• The mother’s age is 35 or more.

• Indication for chromosomal defects.

• Family history of chromosome abnormality (e.g. Trisomy 21 or Down syndrome).

• Parents carry an abnormal chromosome rearrangement.

• A parent is a carrier of a metabolic disorder.

• To assess fetal lung maturity.

Peritoneal Fluid

The collection is called Abdominal Paracentesis. It is collected in the peritoneum of the abdominal cavity which lubricates the surface of tissue that lines the abdominal wall and pelvic cavity. A serous fluid that covers most of the organs in the abdomen.

Ascites

Increased volume of peritoneal fluid.

Pericardial Fluid

A serous fluid secreted by the serous layer of the pericardium into the pericardial cavity.

Pericardial Fluid (purpose)

The pericardial fluid reduces friction within the pericardium by lubricating the epicardial surface allowing the membranes to glide over each other with each beating of the heart.

Pleural Fluid

Serous fluid produced by the serous membrane covering the normal pleura.

Pleura

Refers to the lining of the lungs.

Pleural Fluid (Production & Absorption)

Most fluid is produced by the exudation and parietal circulation via bulk flow and reabsorbed by the lymphatic system.

Pleural Fluid (Abnormal Accumulation Testing)

• Cytopathologic evaluation,

• Clinical microscopy,

• Microbiology,

• Chemical studies,

• and other diagnostic tools for determining causes of abnormal accumulation.

Chemistry Systems in the Clinical Chemistry Department

• Dry reagent strips;

• Wet and dry chemistry systems.

Dry Reagent Strips

• Require the comparison of a color change on the reagent strip color chart.

• Commonly done in the chemical examination for urine in the clinical microscopy section.

Wet Chemistry Systems

Utilizes a spectrophotometer to mechanically measure color change.

Main Difference – Dry vs Wet Systems

• Dry strips: Subjectivity to the reading of the results.

• Wet systems: More accurate.

Types of Measurements in Clinical Chemistry – Qualitative

Gives result in descriptive, non-numeric form. When a dry reagent strip is used, the color chart is utilized to compare the readings.

Types of Measurements in Clinical Chemistry – Quantitative

Gives results in a definitive form, usually in numbers with units.

Plasma Buffy Coat

WBC and platelets are found in the buffy coat area.

Serum (Usage)

Majority of immunology and serology & chemistry tests make use of serum.

Random Urine (Convenience)

Convenient sample that can be collected at any time.

First Morning Sample (Proteins & Analytes)

Useful for detection of proteins or unusual analytes.

24-Hour Urine (Metabolites)

Used for metabolites whose excretion rates may vary with time of day and full 24-hour collection is needed to be representative. 79.

Other Fluids Accepted for Clinical Chemistry Analysis

• Amniotic fluid,

• Pericardial fluid,

• Peritoneal fluid, Pleural fluid (CSF). T

• Typically done to assess the origin of the fluid.