Hematological
function tests
Content
•
Various
hematological function tests
•
Normal
reference ranges of various lab parameters
•
Various
disease conditions correlated with hematological function tests
Objective
After completion of this lecture, student will be able
to:
• Explain
the various hematological function tests
• Explain
the normal reference ranges of various lab parameters
• Explain
the various disease conditions correlated with hematological function tests
Hematological function tests
Introduction
• Complete blood count (CBC) or Complete
Blood Examination (CBE) is routinely ordered test
• Provides useful information on
cellular and non-cellular elements of blood
• Helps in diagnosis of multiple
haematological disorders
Routine tests
• RBC count
• WBC count
• Hemoglobin (Hb)
• Hematocrit (Hct)
• RBC indices (specifically assess
RBCs)
-Mean cell volume (MCV)
-Mean cell hemoglobin (MCH)
-Mean cell hemoglobin
concentration (MCHC)
Reference
range
• RBC count:
-Male: 4.6 to
6.2 X106 cells /mm3
-Female: 4.2 to 5.4
X106 cells /mm3
• WBC count:
5000 to 10,000
cells /cu mm of blood
• Hemoglobin (Hb):
-Male: 14 to
18g/dl
-Female: 12 to
16g/dl
• Hematocrit (Hct) / Packed cell volume (PCV):
It is the percentage volume of
blood that is composed of erythrocytes
Range:
-Male:
42 to 52 %
-Female:
37 to 47%
• Mean cell volume (MCV):
–It is an estimate of the average volume of RBCs
-Derived by dividing Hct by RBC
count
Range:
-Male:
80 to 96 fl (femtolitres – 10 — 15)
-Female:
82 to 98 fl
– Microcytic anaemia: âMCV
– Macrocytic anaemia: áMCV
• Mean cell haemoglobin (MCH):
– It is the percent volume of Hb
per RBC
– Derived by dividing Hb by RBC
count
Range: 27 to 33
pg /cell [picograms = 10 –12]
– Increase in folate deficiency
& decrease in iron deficiency
-A low MCH corresponds with
hypochromic RBCs – as seen in iron deficiency anaemia
• Mean cell haemoglobin concentration (MCHC):
-It is derived by dividing Hb by
Hct
Range:
31 to 35 g/dl
-Iron deficiency is the only
anaemia in which the MCHC is low
Assessment of anaemia
Possible
causes
• Macrocytic anaemia:
-Vitamin B12
deficiency
-Folic acid
deficiency
-Drug induced
bone marrow toxicity
• Normocytic anaemia:
-Acute blood
loss
-Haemolytic
anaemia
-Drug induced
• Microcytic anaemia:
-Iron deficiency
-Drug induced
Laboratory
findings
Erythrocyte sedimentation rate (ESR):
-Rate at which the erythrocytes
settle down
Range:
-Male:
1 to 15 mm / hour
-Females:
1 to 20 mm / hour
-Much physiological condition alters
the normal values of ESR
Physiological
condition that alters the normal values of ESR
|
Increased ESR |
Decreased ESR |
|
Advanced age Female gender Infection Macrocytic anaemia Normocytic anaemia Pregnancy Rheumatoid arthritis |
Congestive cardiac failure Microcytic anaemia Sickle cell anaemia Drugs like corticosteroids |
White Cell Count (WCC)
White Cell Count (WCC)
• Describes
the number of leucocytes circulating in peripheral blood
Total WCC subdivided into
- Granular
white cells-N,E,B - Mono-nuclear
cells-Lymphocytes and monocytes
• Leucopoenia
– WCC is
significantly lower than reference range
• A
specific cell maybe low ( neutropenia, lymphopaenia)
Causes for Leucopoenia
Ø Neoplastic
disease- malignant cells compromise granulopoesis
Ø Drugs
as an adverse effect
• Cytotoxic
drugs
• Immunosuppressant
drugs
• Antibiotics
(Minocyclin)
• Anti-convulsants
(Lamotrigine)
• DMARDS
• Psychotropic
agents- clozapine
Ø Exposure
to ionizing radiations
Ø Exposure
to pesticides or herbicides
Causes for elevated WCC
Ø Infections
such as
• UTI
• Bacterial
pneumonia
• TB
• Meningitis
Ø Drugs
(iatrogenic increase)
• Corticosteroids
• Lithium
Ø Hematological
malignancy like Leukemia, Lymphoma
• Eosinophilia-
elevated eosinophils
• WCC also monitored as a guide to the response
to treatment of an infection
Platelet count
Platelet count (reference range 150-450 x 103 /microliter)
• Minor
to moderate increase – surrogate marker
of inflammation
• Thrombocytopenia
– decreased
platelet count
Causes of Thrombocytopenia
• Severe
iron deficiency anemia
• Liver
disease
• Fulminant
infectious diseases
• Drug
induced- heparin, quinine and thiazide diuretics
Other laboratory data
CRP & ESR – Markers of inflammation
• Serum
amylase – acute
pancreatitis
• Creatine
kinase – muscle cells
damage
Summary
• RBC count:
-Male: 4.6 to
6.2 X106 cells /mm3
-Female: 4.2 to
5.4 X106 cells /mm3
• A low MCH corresponds with
hypochromic RBCs – as seen in iron deficiency anaemia
• Much physiological condition alters
the normal values of ESR
