Hematological function tests

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

  1. Granular
    white cells-N,E,B

  2. 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

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