Transcript Diagnostic Laboratory Blood Tests

Diagnostic Laboratory
Blood Tests
Complete Blood Count and
Blood Chemistry Profiles
Blood Counts
Complete Blood Count
Evaluations of cellular parameters
 Types of cells
 Numbers of cells
 Size and volume of cells

CBC

Provides a “snap shot “ of the
hematopoietic system at a specific point in
time.
CBC Components





White blood cell count
Differential count
Red blood cell count
Hematocrit
Hemoglobin
Mean corpuscular
volume
 Mean corpuscular
hemoglobin
 Mean corpuscular
hemoglobin
concentration

White Blood Count (WBC)
White blood cells (leukocytes) are the
disease fighting cells of the immune
system.
 Only about 1% of blood cells are WBCs
 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
 Different disease states affect the WBC in
different ways

WBC Methods

Hemocytometer

Automated cell counters

Quantitative Buffy Coat Analysis
Manual Hemocytometer
Manual counting is the oldest and most
time consuming method of determining
cell counts
 Special slides and diluting fluids are
required
 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

Can be performed in a mobile clinic
Limitations of Manual Counts

Time consuming (staff expense)

Inherent error (20%), even with skilled
staff

Requires well trained and meticulous
personnel
Manual Counts
WBC count is the most frequently
performed hemocytometer count
 RBC counts are very inaccurate
 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
 All types are more accurate than manual
methods
 Results are obtained rapidly

Types

Semi-automated requires some sample
preparation by technical staff

Fully automated performs all steps itself
Automated Cell Counter
Impedance methods

All make use of Coulter principle
Advantages
Faster and more effective use of staff time
 Newer models store calibrations for
multiple species
 Can perform most of components of a
complete blood count

Limitations
Cannot perform differential counts
 Cannot recognize reticulocytes
 Cannot reliably differentiate between
WBCs and nucleated RBCs
 Several artifacts can create false counts

Quantitative Buffy Coat Analysis
QBC is based on differential centrifugation
 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)
 Automated reader scans buffy coat and
records percentages of aggregates

Advantages of QBC Analysis
Efficient and economical method
 Simple to operate
 Good for rapid screening in office
 The system flags abnormal or unexpected
results

Limitations of QBC Analysis
Cannot produce a complete differential
count
 Cannot distinguish between lymphocytes
and monocytes
 Does not distinguish between segs and
bands

Increased WBCs

Bacterial infections generally increase the
numbers of white cells present
Pyometra
 Bacterial pneumonia
 Peritonitis

Decreased WBCs

Viral infections tend to reduce numbers of
WBCs
Parvovirus
 Canine Distemper
 Feline panleukopenia

Decreased WBCs
Immune system inadequacy
 Bone marrow disease
 Overwhelming bacterial infection

Differential Counts
Important in order to interpret the WBC
results
 Gives much of the information needed to
interpret WBCs
 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
 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

Hematocrit
Measures the percentage of RBCs in the
total blood
 Can give information about the animal’s
state of hydration
 May show evidence of RBC destruction in
the spleen

Hemoglobin
Hemoglobin is the oxygen carrying protein
in the RBC
 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

Mean Corpuscular Volume
MCV
 Measures the size of the RBCs

Mean Corpuscular Hemoglobin
MCH
 Reflects the average weight of the
hemoglobin in the RBCs

Mean Corpuscular Hemoglobin
concentration
MCHC
 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
 Nutrients
 Carrying agents
 Catalysts
 Waste matter
Blood Chemistry
Substances are present in minute amounts
 Each substance contributes to the overall
health of the patient
 Increases or decreases of chemicals can
be good indicators of the patient’s
condition
 Can give valuable aid in making a
diagnosis

Aspartate Aminotransferase
AST
 Formerly called serum glutamic
oxaloacetic transaminase (SGOT)
 Enzyme
 Levels increase with liver or severe muscle
injury

Alanine Aminotransferase
ALT
 Formerly known as serum glutamic
pyruvate transaminase
 Enzyme
 Levels increase in general liver injury

Total Bilirubin
T Bili
 Measures the total amount of all bilirubin
in the serum
 Bilirubin is a pigment released in the
destruction of RBCs
 Increased levels:

 Intravascular hemolysis
 Primary liver or bile duct disease
Direct Bilirubin
D Bili
 Conjugated bilirubin
 Bilirubin that has been combined with
other compounds by the liver
 Increases levels often associated with
primary liver disease

Indirect Bilirubin
I Bili
 Unconjugated bilirubin
 Bilirubin that has not yet been combined
with other substances
 Increased levels usually associated with
abnormal hemolysis

Alkaline Phosphatase
Alk Phos
 Enzyme
 Related to bone, liver, bile duct system
 Increased levels:

 Young, growing animals
 Bone disease
 Liver disease
 Bile duct blockage
 Steroids and anticonvulsants
Total Protein
T Prot or TP
 Measure both albumin and globulin
 Gives very general information
 Further division of proteins needed for
meaningful interpretation

Albumin
ALB
 Major plasma protein
 Transports
substances
throughout body
 Increases:

 Dehydration

Decreases:
 Reduced production by
liver
 Malnutrition
 Chronic liver disease
 Kidney disease
 Tissue fluid loss from
wounds, burns
Globulin
GLOB
 Blood protein
 Antibodies
 Indicator of immune function

Cholesterol
Chol
 Increases due to

 Liver disease
 Diet
 Thyroid disease
 Genetic abnormalities
Blood Urea Nitrogen
BUN
 Associated with kidney function
 Levels increase with:

 Dehydration
 High dietary protein
 Small Bowel hemorrhage
 Kidney disease
Creatinine
Creat
 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
 Mineral
 Levels are regulated by the kidneys
 Linked with calcium , vitamin D,
parathormone
 Increased in young, growing animals
 Increases occur with aging kidneys and
kidney failure

Calcium
Ca+
 Mineral
 Important for skeletal strength
 Needed for nervous system function
 Regulated by parathyroid glands
 Linked to Vit D, calcitonin, and others

Glucose
Gluc
 Essential source of energy for all cells
 Reacts to:

 Insulin levels
 Diet
 Glucagon
 Liver function
Glucose increases
Hyperglycemia
 After eating
 Stress
 Exercise
 Acute pancreatitis
 Some drugs

Glucose decreases
Hypoglycemia
 Malnutrition
 Parasitism
 Increased insulin

 Administration of overdose
 insulin producing tumor
Amylase
Pancreatic enzyme
 Levels increase in

 Acute pancreatitis
 Kidney disease
Lipase
Pancreatic enzyme
 Levels increase in

 Acute pancreatitis
 Kidney disease
Sodium
Na+
 Major blood electrolyte
 Filtered by renal glomerulus, reabsorbed
by renal tubules

Sodium

Increased levels:
–
–
–
–
Dehydration
Increased salt intake
Diabetes insipidus
Kidney failure

Decreased levels:
– Vomiting and Diarrhea
(can lead to metabolic
acidosis)
– CHF
– Adrenal malfunction
(Addison’s disease)
– Diabetes mellitus
Chloride
CHL
 An electrolyte that balances sodium and
potassium
 Increased levels indicate changes in
overall electrolyte balance

Potassium
K+
 Levels linked to Na+
 Controlled by hormone aldosterone

Potassium
Hyperkalemia
 Increases:

– Very serious
– Kidney failure
– Adrenal malfunction
Hypoklalemia
 Decreases:

–
–
–
–
Decreased intake
Excessive loss
Vomiting, diarrhea
Kidney disease
Creatine Kinase

CK
 Formerly called creatine phosphokinase, or CPK
Associated with skeletal muscle or heart
muscle damage
 Increases with:

 Myositis
 Trauma
 Heart damage
Uric Acid

Blood uric acid reflects the end product of
purine metabolism

Increases in:
 General liver disease
 Genetic abnormalities in metabolism (Dalmatians)
T3
Triiodothyronine
 Three iodine atoms attached to thyroxine
 Thyroid hormone
 Regulates metabolism of all body cells

T3

Increase
– Hyperthyroidism due
to increased thyroid
gland activity
– Tumors
– Rare in dogs
– Common in cats

Decrease
– In cases of reduced
thyroid function
– In any generalized
illness
– Very low if animal is
gravely ill
T4
Tetraiodothyronine (4 iodine molecules)
 Converted to T3 by the liver
 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
– Tumors
– Thyroid gland
hyperplasia

Decrease
– Reduced thyroid gland
function