Diagnostic Laboratory Blood Tests Complete Blood Count and Blood Chemistry Profiles

Blood Counts

Complete Blood Count Evaluations of cellular parameters Evaluations of cellular parameters Types of cells Types of cells Numbers of cells Numbers of cells Size and volume of cells Size and volume of cells

CBC Provides a “snap shot “ of the hematopoietic system at a specific point in time. Provides a “snap shot “ of the hematopoietic system at a specific point in time.

CBC Components White blood cell count White blood cell count Differential count Differential count Red blood cell count Red blood cell count Hematocrit Hematocrit Hemoglobin Hemoglobin Mean corpuscular volume Mean corpuscular volume Mean corpuscular hemoglobin Mean corpuscular hemoglobin Mean corpuscular hemoglobin concentration Mean corpuscular hemoglobin concentration

White Blood Count (WBC) White blood cells (leukocytes) are the disease fighting cells of the immune system. White blood cells (leukocytes) are the disease fighting cells of the immune system. Only about 1% of blood cells are WBCs Only about 1% of blood cells are WBCs Large numbers of WBCs can be produced rapidly if needed Large numbers of WBCs can be produced rapidly if needed

White Blood Count (WBC) The WBC tells the total number of white cells present in a specified volume of blood The WBC tells the total number of white cells present in a specified volume of blood Different disease states affect the WBC in different ways Different disease states affect the WBC in different ways

WBC Methods Hemocytometer Hemocytometer Automated cell counters Automated cell counters Quantitative Buffy Coat Analysis Quantitative Buffy Coat Analysis

Manual Hemocytometer Manual counting is the oldest and most time consuming method of determining cell counts Manual counting is the oldest and most time consuming method of determining cell counts Special slides and diluting fluids are required Special slides and diluting fluids are required Method can be used for counting cells in other body fluids and effusions Method can be used for counting cells in other body fluids and effusions

Advantages of Manual Counts Manual counting is the least expensive in terms of equipment and supplies Manual counting is the least expensive in terms of equipment and supplies Can be performed in a mobile clinic Can be performed in a mobile clinic

Limitations of Manual Counts Time consuming (staff expense) Time consuming (staff expense) Inherent error (20%), even with skilled staff Inherent error (20%), even with skilled staff Requires well trained and meticulous personnel Requires well trained and meticulous personnel

Manual Counts WBC count is the most frequently performed hemocytometer count WBC count is the most frequently performed hemocytometer count RBC counts are very inaccurate RBC counts are very inaccurate Meticulous attention to detail is necessary to achieve consistent cell count results when using manual methods Meticulous attention to detail is necessary to achieve consistent cell count results when using manual methods

Hemocytometer

Automated Cell Counter Several types now available for use in vet settings Several types now available for use in vet settings All types are more accurate than manual methods All types are more accurate than manual methods Results are obtained rapidly Results are obtained rapidly

Types Semi-automated requires some sample preparation by technical staff Semi-automated requires some sample preparation by technical staff Fully automated performs all steps itself Fully automated performs all steps itself

Automated Cell Counter

Impedance methods All make use of Coulter principle All make use of Coulter principle

Advantages Faster and more effective use of staff time Faster and more effective use of staff time Newer models store calibrations for multiple species Newer models store calibrations for multiple species Can perform most of components of a complete blood count Can perform most of components of a complete blood count

Limitations Cannot perform differential counts Cannot perform differential counts Cannot recognize reticulocytes Cannot recognize reticulocytes Cannot reliably differentiate between WBCs and nucleated RBCs Cannot reliably differentiate between WBCs and nucleated RBCs Several artifacts can create false counts Several artifacts can create false counts

Quantitative Buffy Coat Analysis QBC is based on differential centrifugation QBC is based on differential centrifugation Uses special tubes that contain a float that has the same density as the buffy coat Uses special tubes that contain a float that has the same density as the buffy coat When spun under high speed, the buffy coat components are separated out by density (weight) When spun under high speed, the buffy coat components are separated out by density (weight) Automated reader scans buffy coat and records percentages of aggregates Automated reader scans buffy coat and records percentages of aggregates

Advantages of QBC Analysis Efficient and economical method Efficient and economical method Simple to operate Simple to operate Good for rapid screening in office Good for rapid screening in office The system flags abnormal or unexpected results The system flags abnormal or unexpected results

Limitations of QBC Analysis Cannot produce a complete differential count Cannot produce a complete differential count Cannot distinguish between lymphocytes and monocytes Cannot distinguish between lymphocytes and monocytes Does not distinguish between segs and bands Does not distinguish between segs and bands

Increased WBCs Bacterial infections generally increase the numbers of white cells present Bacterial infections generally increase the numbers of white cells present Pyometra Pyometra Bacterial pneumonia Bacterial pneumonia Peritonitis Peritonitis

Decreased WBCs Viral infections tend to reduce numbers of WBCs Viral infections tend to reduce numbers of WBCs Parvovirus Parvovirus Canine Distemper Canine Distemper Feline panleukopenia Feline panleukopenia

Decreased WBCs Immune system inadequacy Immune system inadequacy Bone marrow disease Bone marrow disease Overwhelming bacterial infection Overwhelming bacterial infection

Differential Counts Important in order to interpret the WBC results Important in order to interpret the WBC results Gives much of the information needed to interpret WBCs Gives much of the information needed to interpret WBCs To date, no machine is able to perform this task adequately and completely To date, no machine is able to perform this task adequately and completely

Red Blood Cell Count The measurement of RBCs is a way of evaluating the blood’s ability to deliver oxygen to tissues and to carry carbon dioxide away The measurement of RBCs is a way of evaluating the blood’s ability to deliver oxygen to tissues and to carry carbon dioxide away Changes in the morphology of RBCs can give information about bone marrow function Changes in the morphology of RBCs can give information about bone marrow function Some infectious agents or parasites may be seen on the RBC surface Some infectious agents or parasites may be seen on the RBC surface

Hematocrit Measures the percentage of RBCs in the total blood Measures the percentage of RBCs in the total blood Can give information about the animal’s state of hydration Can give information about the animal’s state of hydration May show evidence of RBC destruction in the spleen May show evidence of RBC destruction in the spleen

Hemoglobin Hemoglobin is the oxygen carrying protein in the RBC Hemoglobin is the oxygen carrying protein in the RBC Low levels of Hgb indicate genetic problems, inadequate iron, inadequate B vitamins Low levels of Hgb indicate genetic problems, inadequate iron, inadequate B vitamins High levels of Hgb may indicate abnormalities such as high iron intake, a toxin, or internal organ malfunction High levels of Hgb may indicate abnormalities such as high iron intake, a toxin, or internal organ malfunction

Mean Corpuscular Volume MCV MCV Measures the size of the RBCs Measures the size of the RBCs

Mean Corpuscular Hemoglobin MCH MCH Reflects the average weight of the hemoglobin in the RBCs Reflects the average weight of the hemoglobin in the RBCs

Mean Corpuscular Hemoglobin concentration MCHC MCHC Measures the amount of hemoglobin in a given volume of packed red cells Measures the amount of hemoglobin in a given volume of packed red cells

Blood Chemistry

Blood Chemistry Values Blood chemistry panels measure a variety of substances dissolved in the plasma of blood Blood chemistry panels measure a variety of substances dissolved in the plasma of blood  Nutrients  Carrying agents  Catalysts  Waste matter

Blood Chemistry Substances are present in minute amounts Substances are present in minute amounts Each substance contributes to the overall health of the patient Each substance contributes to the overall health of the patient Increases or decreases of chemicals can be good indicators of the patient’s condition Increases or decreases of chemicals can be good indicators of the patient’s condition Can give valuable aid in making a diagnosis Can give valuable aid in making a diagnosis

Aspartate Aminotransferase AST AST Formerly called serum glutamic oxaloacetic transaminase (SGOT) Formerly called serum glutamic oxaloacetic transaminase (SGOT) Enzyme Enzyme Levels increase with liver or severe muscle injury Levels increase with liver or severe muscle injury

Alanine Aminotransferase ALT ALT Formerly known as serum glutamic pyruvate transaminase Formerly known as serum glutamic pyruvate transaminase Enzyme Enzyme Levels increase in general liver injury Levels increase in general liver injury

Total Bilirubin T Bili T Bili Measures the total amount of all bilirubin in the serum Measures the total amount of all bilirubin in the serum Bilirubin is a pigment released in the destruction of RBCs Bilirubin is a pigment released in the destruction of RBCs Increased levels: Increased levels:  Intravascular hemolysis  Primary liver or bile duct disease

Direct Bilirubin D Bili D Bili Conjugated bilirubin Conjugated bilirubin Bilirubin that has been combined with other compounds by the liver Bilirubin that has been combined with other compounds by the liver Increases levels often associated with primary liver disease Increases levels often associated with primary liver disease

Indirect Bilirubin I Bili I Bili Unconjugated bilirubin Unconjugated bilirubin Bilirubin that has not yet been combined with other substances Bilirubin that has not yet been combined with other substances Increased levels usually associated with abnormal hemolysis Increased levels usually associated with abnormal hemolysis

Alkaline Phosphatase Alk Phos Alk Phos Enzyme Enzyme Related to bone, liver, bile duct system Related to bone, liver, bile duct system Increased levels: Increased levels:  Young, growing animals  Bone disease  Liver disease  Bile duct blockage  Steroids and anticonvulsants

Total Protein T Prot or TP T Prot or TP Measure both albumin and globulin Measure both albumin and globulin Gives very general information Gives very general information Further division of proteins needed for meaningful interpretation Further division of proteins needed for meaningful interpretation

Albumin ALB ALB Major plasma protein Major plasma protein Transports substances throughout body Transports substances throughout body Increases: Increases:  Dehydration Decreases: Decreases:  Reduced production by liver  Malnutrition  Chronic liver disease  Kidney disease  Tissue fluid loss from wounds, burns

Globulin GLOB GLOB Blood protein Blood protein Antibodies Antibodies Indicator of immune function Indicator of immune function

Cholesterol Chol Chol Increases due to Increases due to  Liver disease  Diet  Thyroid disease  Genetic abnormalities

Blood Urea Nitrogen BUN BUN Associated with kidney function Associated with kidney function Levels increase with: Levels increase with:  Dehydration  High dietary protein  Small Bowel hemorrhage  Kidney disease

Creatinine Creat Creat Breakdown product of skeletal muscle metabolism Breakdown product of skeletal muscle metabolism –Creatinine is filtered out by the kidneys –Used with BUN to determine kidney function  Not influenced by diet or GI bleeding

Phosphorus Phos Phos Mineral Mineral Levels are regulated by the kidneys Levels are regulated by the kidneys Linked with calcium, vitamin D, parathormone Linked with calcium, vitamin D, parathormone Increased in young, growing animals Increased in young, growing animals Increases occur with aging kidneys and kidney failure Increases occur with aging kidneys and kidney failure

Calcium Ca+ Ca+ Mineral Mineral Important for skeletal strength Important for skeletal strength Needed for nervous system function Needed for nervous system function Regulated by parathyroid glands Regulated by parathyroid glands Linked to Vit D, calcitonin, and others Linked to Vit D, calcitonin, and others

Glucose Gluc Gluc Essential source of energy for all cells Essential source of energy for all cells Reacts to: Reacts to:  Insulin levels  Diet  Glucagon  Liver function

Glucose increases Hyperglycemia Hyperglycemia After eating After eating Stress Stress Exercise Exercise Acute pancreatitis Acute pancreatitis Some drugs Some drugs

Glucose decreases Hypoglycemia Hypoglycemia Malnutrition Malnutrition Parasitism Parasitism Increased insulin Increased insulin  Administration of overdose  insulin producing tumor

Amylase Pancreatic enzyme Pancreatic enzyme Levels increase in Levels increase in  Acute pancreatitis  Kidney disease

Lipase Pancreatic enzyme Pancreatic enzyme Levels increase in Levels increase in  Acute pancreatitis  Kidney disease

Sodium Na+ Na+ Major blood electrolyte Major blood electrolyte Filtered by renal glomerulus, reabsorbed by renal tubules Filtered by renal glomerulus, reabsorbed by renal tubules

Sodium Increased levels: Increased levels: –Dehydration –Increased salt intake –Diabetes insipidus –Kidney failure Decreased levels: Decreased levels: –Vomiting and Diarrhea (can lead to metabolic acidosis) –CHF –Adrenal malfunction (Addison’s disease) –Diabetes mellitus

Chloride CHL CHL An electrolyte that balances sodium and potassium An electrolyte that balances sodium and potassium Increased levels indicate changes in overall electrolyte balance Increased levels indicate changes in overall electrolyte balance

Potassium K+ K+ Levels linked to Na+ Levels linked to Na+ Controlled by hormone aldosterone Controlled by hormone aldosterone

Potassium Hyperkalemia Hyperkalemia Increases: Increases: –Very serious –Kidney failure –Adrenal malfunction Hypoklalemia Hypoklalemia Decreases: Decreases: –Decreased intake –Excessive loss –Vomiting, diarrhea –Kidney disease

Creatine Kinase CK CK  Formerly called creatine phosphokinase, or CPK Associated with skeletal muscle or heart muscle damage Associated with skeletal muscle or heart muscle damage Increases with: Increases with:  Myositis  Trauma  Heart damage

Uric Acid Blood uric acid reflects the end product of purine metabolism Blood uric acid reflects the end product of purine metabolism Increases in: Increases in:  General liver disease  Genetic abnormalities in metabolism (Dalmatians)

T3 Triiodothyronine Triiodothyronine Three iodine atoms attached to thyroxine Three iodine atoms attached to thyroxine Thyroid hormone Thyroid hormone Regulates metabolism of all body cells Regulates metabolism of all body cells

T3 Increase Increase – Hyperthyroidism due to increased thyroid gland activity –Tumors –Rare in dogs –Common in cats Decrease Decrease –In cases of reduced thyroid function –In any generalized illness –Very low if animal is gravely ill

T4 Tetraiodothyronine (4 iodine molecules) Tetraiodothyronine (4 iodine molecules) Converted to T3 by the liver Converted to T3 by the liver Free T4 (FT4) less than 0.1 percent of all T4, not bound to protein Free T4 (FT4) less than 0.1 percent of all T4, not bound to protein  When measured accurately, most predictive of true thyroxine concentrations

T4 Increase Increase –Tumors –Thyroid gland hyperplasia Decrease Decrease –Reduced thyroid gland function