1. Interpreting Clinical Lab Data
M.ABD ELAZIZ, PhD, MD
Professor of clincal pharmacology
Mansoura University

2. GENERAL PRINCIPLES Generally, laboratory tests should be ordered only
1-if the results of the test will affect decisions about the care of the patient.
2- The serum, urine, and other bodily fluids can be analyzed routinely;
3-however, the economic cost of obtaining these data must always be balanced by benefits to patient outcomes.

3. Normal Values
Clinical laboratory test results that appear within a predetermined
range of values are referred to as “normal,” and those outside this range are typically referred to as “abnormal.”
Laboratory findings, both normal and abnormal, can be helpful in Assessing:
clinical disorders, establishing a diagnosis, assessing drug therapy, or evaluating disease progression
. In addition, baseline laboratory tests are often necessary to evaluate disease progression and response to therapy or to monitor the development of toxicities associated with therapy.
Clinical laboratories can analyze sample specimens by different laboratory methods;
therefore, each laboratory has its own set of normal values. Consequently, clinicians should rely on normal values listed by their own clinical laboratory facility when interpreting laboratory tests.

4. Laboratory Error
Avariety of factors can interfere with the accuracy of laboratorytests.
1- Patient-related factors (e.g., age, gender, weight,height, time since last meal) can affect the range of normal values
for a given test.
2- Laboratory-based issues can also influence the accuracy of laboratory values.
For example, a specimencan be spoiled
A-because of improper handling or processing (e.g., hyperkalemia due to hydrolysis of a blood specimen);
B-because it was taken at a wrong time (e.g., fasting blood glucoselevel taken shortly after a meal);
C- because collection was incomplete (e.g., 24-hour urine collection that does not span a full 24-hour period);
3- Errors also can arise due to faulty poor quality reagents (e.g., improperly prepared, outdated);
4-due to technical errors (e.g., human error in reading result, computer-keying error);
5- due to interference from medical procedures (e.g., cardioconversion increases creatine kinase [CK]
serum concentrations);
6-due to dietary effects (e.g., rare meat ingestion can cause a false-positive guaiac test);
7- because medications can interfere either with the testing procedure or by their pharmacologic effects (e.g., thiazides can increase the serum uric acid concentration, β-agonists can reduce serum potassium concentrations).
8-Clinicians might not be aware of when laboratory-related issues arise.
As a result, laboratory findings must always be interpreted carefully, and the validity of a test result questioned when it does not seem to correlate with a patient’s clinical status.

5.    
Side A
Side B   
1 .
aden/o
gland
11.
carcin/o
cancer
2 .
cardi/o
heart
12.
chem/o
chemical
3 .
cis/o
to cut
13.
dermat/o
skin
4 .
enter/o
small intestines
14.
gastr/o
stomach
5 .
gynec/o
female
15.
hemat/o
blood
6 .
hydr/o
water
16.
immun/o
immun
7 .
laryng/o
voice box
17.
morph/o
shape
8 .
nephr/o
kidney
18.
neur/o
nerve
9 .
ophthalm/o
eye
19.
ot/o
ear
1 0 .
path/o
disease
20.
pulmon/o
lung

6. Interpreting Clinical Lab Data
Objectives:
1. Identify the characteristics and function of each type of leukocyte.
2. Identify the significance of comparing the WBC count to the neutrophil count in patients with pneumonia.
3. Identify common causes for increases and decreases in the neutrophil count.
4. State how the “rule of three” is useful for interpretation of the RBC count and indices.

7. Divisions of the Clinical Lab
Hematology
Complete blood count
WBC count
Platelets
RBC count
Chemistry
Electrolytes
Potassium
Sodium
Total CO2
Chloride

8. Divisions of the Clinical Lab
Microbiology
Sputum gram stain
Sputum culture and sensitivity
Pleural fluid culture and sensitivity
Blood Bank
- blood typing and storage

9. CELL MORPHOLOGY

10. Cell Morhphology (neutrophil)
Segmented neutrophil (40-70% of WBCs)
Life span of about 10 days
Moves from bone marrow to blood to tissues
Mature more quickly under stressful conditions
Primary defense for bacterial infections

11. Cell Morhphology (neutrophil)

12. The Neutrophil
Once in the peripheral blood, it can be in the circulating pool (CP) or the marginated pool (MP) (approx. 50%)
cells in MP not counted in CBC
Shift from the MP to the CP can occur with stress, trauma, catecholamines, etc.
This results in a transient leukocytosis
Such leukocytosis can last 4 to 6 hours

14. The Neutrophil Present in band and segmented forms
Bands make up < 5 % of circulating neutrophils normally
“Left shift” is seen as an increase in the number of bands and is common with acute infection
Main function is to locate, ingest, and kill bacteria and other foreign invaders

15. Cause of Neutrophilia Pathologic Drugs Bacterial infection
Certain viruses and fungi
Inflammatory responses to tissue death
Burns
Snake bites
Drugs
steroids
lithium

16. Causes of Neutrophilia (cont.)
Physiologic
Pseudoneutrophilia (shift of cells from the MP to CP)
Catecholamines
Acute stress
Other inflammatory responses
Neoplastic growth
Metabolic disorders

17. Pools of Neutrophils
Bone marrow: many banded forms are present; neutrophilia with lots of bands suggest bone marrow was source
Circulating Pool: used to deal with day to day invasion of the body by organisms
Marginated Pool: no bands; respond to physiologic stimulation

18. Causes of Neutropenia Decreased Production of WBCs
bone marrow diseases
malignancies that affect the bone marrow
Increased Neutrophil Destruction
overwhelming infection
certain bacteria
immune reactions
Pseudoneutropenia (shift of cells from CP to MP)
viral infections
hypothermia

19. Cell morphology (Eosinophil)
Segmented eosinophil
Life span = 14 days
Spends little time in the blood before it locates in the skin, GI tract, or respiratory tract
Only 1% of mature cells are located in blood

20. The Eosinophil
Also function as phagocytes but appear to be less potent than neutrophil
Drawn to sites of hypersensitivity reactions by mast cell chemotactic factors
Often found in sputum of asthmatics
May play a role in pathogenesis of lung dz
Play a role in parasitic infections

21. The Basophils Mature basophil Least common of WBCs (< 2%)
Nucleus does not always segment
Increase in response to same conditions that cause eosinophils to respond

22. The Monocytes Also not common in circulating blood
Stay in blood for about 70 hours
Become macrophages in tissue and live for several months or longer

23. The Monocytes Primary role is phagocytosis
Play large role in ingesting cellular debris
Become “activated” when direct contact with microorganisms occurs
Activated cell has greater motility, enzyme activity and killing capacity (causes fever)
Also play a role in immunity

24. The Lymphocytes May mature into B or T cells
Main function is antigen recognition and immune response
Life span quite varied (up to two years)
Can pass back and forth between blood and tissues

25. Lymphocytes: B & T types
B cells are not only produced in the bone marrow but also mature there.
However, the precursors of T cells leave the bone marrow and mature in the thymus (which accounts for their designation)

26. Types of Lymphocytes
B lymphocytes (or B cells) are most effective against bacteria & their toxins plus a few viruses
T lymphocytes (or T cells) recognize & destroy body cells gone awry, including virus-infected cells & cancer cells.
T cells come in two types: helper cells and suppressor cells; normally the helper cells predominate.

27. Lymphocyte Count: Decreased
AIDS
Bone Marrow suppression
Aplastic Anemia
Steroids
Neurologic Disorders
Multiple Sclerosis
Myasthenia Gravis
Gullain Barre Syndrome

28. Lymphocyte count: Increased
Influenza
Pertussis
Tuberculosis
Mumps
Cytomegalovirus Infection
Infectious Mononucleosis
Infectious Hepatitis
Viral pneumonia

29. Interpreting the CBC What is total white cell count?
If elevated (>11,000), what type of WBC is the culprit?
Is it the neutrophils, eosinophils, lymphocytes, basophils, or monocytes?
Marked leukocytosis is usually due to neutrophils or lymphocytes.

30. Interpreting the CBC Normal Values % Absolute Neutrophils 40 – 70
1800 – 7500
Eosinophils
0 – 6
0 – 600
Basophils
0 – 1
0 – 100
Lymphocytes
20 – 45
900 – 4500
Monocytes
2 – 6

31. Interpreting the CBC
If the neutrophils are causing the leukocytosis, compare the neutrophil % to total WBC.
The % neutrophils indicates the severity of the infection; the total WBC reflects the quality of the immune system

32. Interpreting the CBC (Case # 1)
85 yr old female with pneumonia:
Total WBC is: 11,500
Neutrophil % = 80% (9200) bands = 5%
This indicates that a severe infection is present but the immune system is unable to respond appropriately.
Prognosis poor.

33. Interpreting the CBC (Case # 2)
5 yr old male with pneumonia
WBC = 18,000
Neutrophils = 60% (10,800)
Marked leukocytosis and normal range for neutrophils indicates moderate infection but excellent immune system response
Excellent prognosis

34. Interpreting the CBC (Case #3)
10 yr old male admitted for pneumonia:
WBC: 16,000
neutrophils = 75% (12,000) ( )
Bands = % (800) (0-100)
Eosinophils = 1% (160) (0-600)
Lymphocytes = 10% (1600) ( )
Basophils = 0% (0) (0-100)
Monocytes = 3% (480) ( )

35. Interpreting the CBC (Case #3)
Interpretation
neutrophilia probably due to bacterial pneumonia
left shift indicative of severe infection
the source of the neutrophils is the bone marrow since many bands are present

36. Case Study # 4 20 yr old male admitted following MVA
WBC 14, % neutrophils 1% bands
Leukocytosis due to neutrophilia
History and low per cent of bands suggest pseudoneutrophilia
Due to liberation of marginated neutrophils in the intravascular system

37. Interpreting the CBC What is indicated by leukopenia?
1. Bone marrow failure
cancer e.g. leukemia, lymphoma
2. Overwhelming infection
severe pneumonia pt who has poor immune system and can’t produce enough WBCs
3. Shift of neutrophils to MNP (viral infections and hypothermia)

38. Platelet Count Normal count is 140,000 to 440,000/mm3
Life span of about 10 days
Low platelet counts (thrombocytopenia) cause excessive bleeding
Thrombycytopenia is common with the use of heparin, DIC, bone marrow disease, liver failure and sepsis

39. Platelet

40. Platelet (Activated)

44.   
Side A
Side B
1 .
aden/o
gland
11.
carcin/o
cancer
2 .
cardi/o
heart
12.
chem/o
chemical
3 .
cis/o
to cut
13.
dermat/o
skin
4 .
enter/o
small intestines
14.
gastr/o
stomach
5 .
gynec/o
female
15.
hemat/o
blood
6 .
hydr/o
water
16.
immun/o
immun
7 .
laryng/o
voice box
17.
morph/o
shape
8 .
nephr/o
kidney
18.
neur/o
nerve
9 .
ophthalm/o
eye
19.
ot/o
ear
1 0 .
path/o
disease
20.
pulmon/o
lung

46. without
27.an
without, away from
22.a ,
, against
28. anti-
before, in front of
23.ante
slow
29. brady
, self
24.auto
, within, inner
30. endo
painful, difficult
25.dys-

49. Red Blood Cells

50. Red Blood Cells (Erythrocytes)
Produced in the bone marrow
Life span of about 120 days
Primary function is gas transport
Immature version has nucleus and is called a reticulocyte

51. Interpreting the RBC count
Normal values:
Men: 4.2 – 5.4 million/mm3
Women: 3.6 – 5.0 million/mm3
Anemia –
abnormal Decrease in RBC count
- decreased production
- increased destruction (hemolysis)
- blood loss

52. Interpreting the RBC count
3. Increased RBC count = Polycythemia
A. Primary
B. Secondary
living at altitude
chronic lung/heart disease
tobacco use/carbon monoxide
C. Relative Polycythemia
dehydration

53. Red Blood Cell Indices Mean Corpuscular Volume (MCV)
Volume occupied by a single RBC
Increase in MCV is known as Macrocytic anemia.
Decrease in MCV is known as Microcytic anemia.
Mean Corpuscular Hemoglobin Concentration
(MCHC)
Measure of the concentration of hemoglobin in an average RBC
Decrease in MCHC is known as Hypochromic anemia
Normal is known as Normochromic anemia.

54. Red Blood Cell Indices Normocytic anemias
Blood loss
Hemolytic anemia
Microcytic anemias (<80 fL*)
Iron deficiency
Macrocytic anemias (>100 fL)
Folic acid deficiency
Vitamin B12 deficiency
Some COPD patients
*femtoliters

55. Red Blood Cell Indices

56. Hematocrit

57. The RULE of Three
Applies to normocytic, normochromic erythrocytes only
Useful to detect laboratory error in measuring the Hb, HCT, and RBC count
3 times the RBC count should = Hb
3 times Hb should = Hct

58. The RULE of Three RBC = 3.0 x 1012 3 x 3 = 9
Hb = 9.2 g/dL 3 x 9.2 = 27.6
Hct = 28%

59. Interpreting the Red Blood Cells
CBC: Results Normals
RBC (x1012/L)
Hgb (g/dL) 
Hct %  38%-47%
MCV (m3)  80-96
MCHC %  32-36%
Interpretation: Microcytic, hypochromic anemia; rule of 3 does not apply

60. Reticulocyte Count Normal values: Helpful to identify cause of Anemia
0.5 – 1.5% of RBC
Helpful to identify cause of Anemia
Increase indicates Anemia is due to Blood loss
Decrease indicates Anemia is due to Bone marrow disease

61. Bibliography
Steine-Martin: Clinical Hematology, 2nd edition, Lippincott, Philadelphia,
Kaplan: Clinical Chemistry, 4th edition, Mosby, St. Louis, 2003.
Wilkins: Clinical Assessment in Respiratory Care, 5th edition, Mosby, St. Louis, 2005.