Causes Primary Polycythemia vera (neoplastic). Secondary 1. Associated with hypoxia a. Cardiovascular disease, usually congenital resulting in significant venous admixture.

 

minutes. During this time keep stirring the mixture of

FIG. 9.3: Mixing of anticoaguted tubes

A B C

Clinical Hematology 211

Drabkin’s solution, add 20 μL of blood. Mix well. Read in a

photocolorimeter at 540 nm (green filter).

For this procedure, certified standard hemoglobin

solution may be obtained from reputable laboratory

supply firms. By diluting the known standard hemoglobin

solution, a graph (linear) may be obtained by plotting

the known Hb concentration against the colorimetric

optical density reading so that in future the corresponding

hemoglobin value can directly be read off from the

calibration curve after knowing the optical density of a

particular unknown blood sample.

Sheard-Sanford Oxyhemoglobin Method

Mix 20 mL of 0.1% sodium carbonate and 0.1 mL of blood

or aliquots of these (e.g. 4 mL diluent for 20 μL blood); read

optical density in photometer at 540 nm within 30 minutes.

Photometer calibration should be based on blood iron

determination or oxygen capacity determination.

Other Methods

Alkali Hematin Method

It does not estimate fetal hemoglobin and is no longer

used in routine hemoglobinometry.

Gasometric Method

Van Slyke’s oxygen capacity method. It is an indirect

method, which estimates the amount of hemoglobin

from the amount of oxygen it absorbs. This method is very

complicated for routine clinical work.

Specific Gravity Method

The normal specific gravity of blood ranges from 1.048

to 1.066. The average for men is 1.057 and for women it

is 1.053. From specific gravity of the unknown sample,

its hemoglobin is calculated. This is a very rapid and an

uncomplicated method and finds its main use in screening

potential blood donors for anemia.

Chemical Methods

Obsolete. Hemoglobin is estimated by finding the iron

content.

Sodium Lauryl Sulfate Method

(Available from coral clinical systems, Goa)

This is a KCN-free reagent where SLS substitutes KCN.

The color complex formed is SLS-Hb which is read at 540

nm. The greatest advantage being that all forms of Hb are

converted. The method is relatively free from interferences

due to lipemia and presence of WBCs. Linearity is superior

to that of Cyanmeth Hb method.

Normal Hemoglobin Values

Men 15.5±2.5 g/dL 14–18 g%

Women 14.0±2.5 g/dL 11.5–16.5 g%

Infants full

term cord blood 16.5±3.0 g/dL 13.5–19.5 g%

Children, 1 year 12.0±1.0 g/dL 11.0–13.0 g%

Children 10-12 years 13.0±1.5 g dL 11.5–14.5 g%

According to current WHO specification for males

13.2 g/dL and for females up to 11.7 g/dL Hb are said to be

normal. For children from 3 months to puberty, 10.7 g/dL

is said to be normal Hb level.

ANEMIA

It is defined as reduction in the concentration of

hemoglobin in the peripheral blood below the normal for

the age and sex of the patient.

Diurnal variations: Hb values are highest in the morning

and lowest in the evening. A change in the Hb must be

1.5 g% or more to be considered definitely significant.

Causes of Anemia

1. Blood Loss

• Acute post-hemorrhagic anemia

• Chronic post-hemorrhagic anemia.

2. Impaired Red Cell Formation

a. Disturbance of bone marrow due to deficiency of

substances essential for erythropoiesis

• Iron deficiency anemia

• Megaloblastic macrocytic anemias due to deficiency

of vitamin B12 or folic acid

• Anemia associated with scurvy.

b. Disturbance of bone marrow functions not due to

deficiency of substances essential for erythropoiesis

• Anemia associated with

– Infection

– Renal failure

– Liver disease

– Disseminated malignancy

• Aplastic anemia

• Anemia associated with bone marrow infiltration,

e.g. leukemia, malignant lymphoma, multiple

myeloma, myelosclerosis

• Anemia associated with myxedema and hypopituitarism

• Sideroblastic anemias

• Congenital dyserythropoietic anemias.

212 Concise Book of Medical Laboratory Technology: Methods and Interpretations 3. Increased Destruction of Red Cell (Hemolytic)

Anemia

• Hemolysis due to corpuscular defects (intracorpuscular or intrinsic abnormality)

• Hemolytic anemia due to abnormal hemolytic

mechanisms (extracorpuscular or extrinsic defect).

Polycythemia

Hemoglobin value for the age and sex of the patient is

called polycythemia. Of course, one has to refer to other

parameters as well.

Polycythemia (erythrocytosis) refers to:

¾ Increase in Hb

• Above 18 g% in males

• Above 16.5 g% in females. In addition, there is:

¾ Increase in red cell count:

• Above 6 million/cu mm in males

• Above 5.5 million/cu mm in females.

¾ Increase in hematocrit (PCV)

• Above 55% in males

• Above 47% in females.

Causes

Primary

Polycythemia vera (neoplastic).

Secondary

1. Associated with hypoxia

a. Cardiovascular disease, usually congenital resulting in significant venous admixture.

b. Pulmonary disease resulting in:

• Impaired gas perfusion

• Perfusion of poorly aerated lung

• Pulmonary arteriovenous fistula.

c. High altitude residence.

d. Hypoventilation associated with obesity (Pickwickian syndrome).

e. Hemoglobin variants with increased affinity for

oxygen.

f. Heavy smoking.

g. Methemoglobinemia (rarely).