Lecture 10

Question 1

Anemia

Answer 1

A decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood
Anemia is not a disease but a symptom of conditions – extensive blood loss or blood cell destruction or decreased blood cell formation
Anemia is one of the more common blood disorders
Biochemistry related tests: (Serum)
Iron, Ferritin, B12 & Folate, RBC folate, … (CBC)

Question 2

Iron *

Answer 2

Essential for Hb synthesis
Deficiency can lead to anemia
The most common cause of anemia is iron deficiency
Can be elevated due to hemolytic anemia, increased iron intake, lead poisoning
Iron is mostly stored in the body in the hemoglobin
Also stored as ferritin and hemosiderin in the bone marrow, spleen, and liver

Serum stable up to one week at 4C
Interferences: Hemolysis, anticoagulants
Reference Range
Male 11.6 – 31.7 µmol/L, Female 9.0 – 30.4 μmol/L

Question 3

Vitamin B12 **

Answer 3

Vitamin B12 in food is bound to protein.
HCl of the stomach releases free vitamin B12, combines with intrinsic factor (IF) secreted to form a complex which is absorbed by the ileum
breaks down fats , works with folate to form RBC, nucleic acids and myelin sheath

Serum specimen
Vitamin B12
Most is stored in the liver
Necessary for the formation of blood cells and other body cells
Deficiency cause pernicious anemia, mycrocytic anemia**
Hemolysis is cause for specimen rejection
Reference Range 148 - 590 pmol/L

Question 4

Function of Vitamin B12

Answer 4

Essential with folic acid for RBC maturation
It is vital in fat metabolism.
Nervous system (It is vital in synthesis of myelin sheath of neurons).
Cell replication. It is essential with THF in synthesis of nucleic acids

Question 5

Serum Folate **

Answer 5

Folate is present mainly in liver, leafy vegetables, whole grains and yeast.
Body stores of folate in a normal, healthy adult are about 10mg and are located in liver.
Important for RBC
Folate is necessary to synthesize DNA and repair DNA
Important in aiding rapid cell division and growth
Deficiency leads to macrocytic / megaloblastic anemia
Hemolysis is cause for specimen rejection
Reference Range 4.4 - 31.1 nmol/L

Question 6

RBC folate **

Answer 6

EDTA sample
RBC folate more closely reflect tissue folate stores
More stable than serum folate within the body
Deficiency leads to macrocytic anemia
EDTA sample is required
Test usually includes serum folate
Reference Range 453 -1586 nmol/L**

Question 7

Monosaccharides

Answer 7

Simple sugars e.g. glucose, fructose- fruit grapes, galactose. pentose

Question 8

Disaccharides-

Answer 8

sugars of 2 monosaccharides
Maltose = glucose + glucose - beer
Sucrose = glucose + fructose - simple white sugar
Lactose = glucose + galactose

Question 9

Polysaccharides

Answer 9

Many monosaccharides - Xylose, Lactose

Question 10

Xylose Tolerance Test

Answer 10

Measures the ability of the intestine to absorb the simple sugar, D-xylose
Test is done to determine the cause of malabsorption
Intestinal problems versus malabsorption
Pancreatic enzymes are not required for the absorption of xylose
Samples required: blood and urine (clean catch)
Fasting 8 to 12 hours before test

Question 11

Testing for Xylose

Answer 11

Avoid exercise before test
Patient is required to take 5 or 25 grams D-xylose dissolved in 250 ml of water
Followed by an additional 750 ml water
Record the time
Sample collection similar to OGTT – fasting, timed
Report both urine and blood xylose level
Seen in Celiac Disease and Tropical Sprue

Question 12

Lactose Tolerance Test

Answer 12

Measures the ability/inability of the intestine to break down/digest lactose
Lactose – a type of sugar found in milk and other dairy products
Requires the enzyme lactase for digestion
Deficiency may cause a range of abdominal symptoms
Lactase breaks down lactose into two simpler forms of sugar – glucose and galactose

Question 13

Testing – Oral Tolerance Tests

Answer 13

milar to OGTT – fasting, lactose drink, samples
Measure the blood glucose level
Can also be detected on urine samples

OGTT – Lecture #5**
Require a FBS and a urine sample
Patient consumes a glucose drink
50, 75, or 100 g glucose dose
75g glucose in 300 mL solution most often given
Usually consumed within 5 minutes
Glucose test repeated 30 minutes, 1, 2, 3 hours after consuming the drink (blood and urine samples)
2 & 3 hour test sometimes used for diabetes – levels near normal after 2 hr
For pregnant women, a glucose drink of 50 gms
Difficult to administer – requiring much time and repeated blood tests

Question 14

Therapeutic Drug Screening/Monitoring

Answer 14

To determine the presence or absence of specified drugs or their metabolites
Specimen in Biochemistry lab – blood (serum) and/or urine
Could also include hair (Children Aids Society) – its not done anymore

Question 15

DRUGS – THERAPEUTIC DRUGS OF ABUSE

Answer 15

Blood specimens are required for testing the following drugs:

Alcohols: ethanol (liquor) and methanol (windshield wash)
Analgesic, narcotic pain drugs - anti-inflammatory- acetaminophen, tylenol, salicylate, ASA (aspirin) or
Antiepileptic/seizure- phenytoin (dilantin), carbamazepine, valproic acid, phenobarbital
Antibiotics- gentamicin, vanomycin
Anti-psychotic/anti-manic- lithium, risperidone
Anti-convulsive - Respiratory ailments eg asthma- theophylline

Question 16

Drug of Abuse Detection

Answer 16

Urine sample is used to test for all the other drugs
Examples of drug classes
Amphetamines - cocaine
Opiates/opioids – fentanyl, oxycontin 
 Hallucinogenic – PCP, LSD
 Anti-depressants – Barbiturates, Prozac, valium
Antipsychotics - benzodiazepines
Cannabinoids – cannabis (marijuana)

Question 17

Blood Alcohol Collection

Answer 17

Ethanol, isopropanol, methanol, ethylene glycol, acetone:
No alcohol swab during venipuncture ( e.g. 70% isopropanol, 70% ethanol)
Use alternative antiseptic (e.g. quaternary ammonium compounds, halogenated phenol derivatives, - supplied by workplace)
Specimen - serum from red or gold top; cap tightly to prevent evaporation (volatile

Question 18

72 Hour Fecal Fat Collection

Answer 18

Stool collection for fat absorption / elimination to diagnose dietary malabsorption or maldigestion
Symptoms such as malnourishment, GI upset, weight loss are common
Patient given a pre-weighed one gallon metal can with collection instructions
A normal diet containing about 100 grams of fat per day for 3 days before starting the test is required

Question 19

Fecal Collection

Answer 19

Patient 3 days fecal collection instructions-
Collect all stool in the1 gallon can
Documenting start date/time and end date/time over 72 hours on label provided
Do not fill > 1/3 full
Refrigerate during collection to minimize bacterial action
Close lid tightly and bring to lab within 24 hours of end of collection
Lipid is extracted and if > than 7gms/day indicates malabsorption of fats

Question 20

Sweat Chloride Test

Answer 20

Purpose - measure the concentration of chloride that is excreted in sweat
Used to diagnose cystic fibrosis
Cystic fibrosis- a disease of the mucus and sweat glands
Genetic defect with no known cure
Affecting the way chloride moves in and out of cells

Question 21

Symptoms of Cystic Fibrosis

Answer 21

Disease symptoms:
Recurrent intestinal or respiratory disease in a child
Malnourished body
Painful/swollen abdomen
Bulky/foul smelling stools

Question 22

Cortisol

Answer 22

Cortisol produced by the adrenal glands but is controlled by the hypothalamus and pituitary gland
It is the body’s main stress hormone, works with the brain to control mood, motivation and fear

Question 23

Role of Cortisol

Answer 23

Important role

1) Helps the body respond to stress
2) Regulates blood pressure
3) Keep inflammation down
4) Increase blood sugar
5) Controls sleep and wake patterns

Question 24

Tumor/Cancer Markers

Answer 24

Substances found in the blood, urine, or body tissues that can be elevated in cancer

Used to detect tumor recurrences and assess therapy

Question 25

Three basic classes of cancer markers

Answer 25

Tumour specific / Tumour-associated antigen- Carcinoembryonic Antigen – CEA
Enzymes- Acid Phosphatase
Hormones- HCG
look at slide

Question 26

Blood collection:

Answer 26

Venous or capillary
Serum most often used (SST)
Could also include plasma (heparinized) or whole blood

Serum is commonly used for most clinical chemistry tests
Depending on the analyzer and methods, serum, plasma and/or whole blood may be used
Be familiar with all blood collection tubes and anticoagulants
Chemistry – SST, ed top, green, grey, royal blue

Question 27

Arterial

Answer 27

For blood gas measurements – Heparinized sample

Place on ice and analyze immediately

Question 28

what should not happen when collecting blood ***

Answer 28

Avoid collecting blood from an arm with IV, or collecting above an IV line
Specimen must be free from hemolysis
Falsely elevated results – K+, LD, AST, Mg+, Iron, Vitamin B12, Folate
Timing of specimen – fasting
Avoid delay in delivery to the lab or testing – test within one hour of collection
Refrigerate the serum at 40C if testing is delayed

Question 29

Hospitals / Private Labs

Answer 29

High volume testing
Capable of performing a variety of tests
Less variation in technique
Capable of producing accurate results
Laboratories are required to run controls for each test performed
Controls must fall within ± 2SD
Shorter TAT - Improved rate of diagnosis and treatment

Question 30

Principles of Instrumentation include:

Answer 30

Freezing Point Technology
Photometry / Spectrophotometry
Ion-Selective Electrodes

Question 31

Osmolarity –

Answer 31

Freezing Point Technology

Measures the number of particles in a solution
Very accurate method in determining the kidneys ability to concentrate or dilute urine
Not affected by the density of particles as in the routine SG methods
Determination can be done on urine and serum samples

Question 32

Photometers/Spectrophotometers

Answer 32

Instruments that measure light intensity
Determine the concentration of colored solutions at a specific wavelength
Light absorbed by the solution is referred to as Absorbance (A)
Used to calculate concentration of analytes
Concentration is directly proportional to absorbance
The more concentrated the solution:
The greater the (A)
The less the (%T)

Two electrodes are used in analysis - like pH
The reference electrode contains a known concentration of the ion of interest
The other electrode is responsive only to the ion of interest – measuring electrode
The difference in concentration between the reference electrode and the unknown solution is used to determine the concentration of the unknown

Question 33

Insulin

Answer 33

a hormone produced by the beta cells of the pancreas
During an activity - Increase in cellular uptake of glucose and the rate of glycolysis increases to produce energy
Several hours after a meal, the blood sugar level goes down and Glucagon produced by the Alpha cells of the pancreas signals the liver and muscle to change stored glycogen back into glucose - look at the slide
(Pancreas also produce digestive enzymes)

Question 34

HCG

Answer 34

glycoprotein and contains two sub-units – Alpha and Beta
HCG doubles every 48/72 hours
Peak levels are reached about the 12th week of pregnancy
Declines about the third month, decreases to a level of 10,000 -20,000 IU/ml till end of pregnancy
Not detectable a few days after delivery
maintains progesterone production that is critical for pregnancy
Progesterone enriches the uterus with a thick lining of blood vessels and capillaries necessary to sustain the growing fetus
Levels of hCG may be measured in the blood or urine
In Urine - referred to as pregnancy test (measuring Beta HCG)
In Blood – Beta human chorionic gonadotropin -
βhCG