Hemoglobin Variant Analysis - Edta Whole Blood

Other names:Hemoglobin Evaluation, Hemoglobinopathy Evaluation

Hemoglobin is the protein in Red Blood cell. This is responsible for giving red blood cells its characteristic red color. It is also responsible for carrying oxygen to various parts of body.

Haemoglobin is a made up of two parts, heme an iron containing portion, and other protein portion known as globin. Different types of globins are alpha, beta, gamma and delta.

Normal hemoglobin types include:

• Normal types of Hemoglobin are HbA (this is the most abundant type and makes up about 95-98% of Hb found in adults). HbA contains two alpha protein chains and two beta protein chains.
• HbA2 contains two alpha and two delta chains and makes up about 2-3% of Hb
• HbF is present in less than 1% Hb and has two alpha and two gamma chains.

Any changes in the globin chains lead to blood disorders. The changes in the globin structure affects the structure of hemoglobin, production rate, stability and how it behaves. The most common disorder is called as Thalassemia.

The doctor will order this test when there is an abnormal test results when CBC is conducted or an abnormal blood smear that suggests abnormalities in hemoglobin.

There are a few common hemoglobin variants. The hemoglobin variant analysis test helps identify these variants. The tests results are useful to manage the condition.

• Hemoglobin S variant is seen in people with sickle cell anemia
• Hemoglobin C Variant causes a mild case of hemolytic anemia and to an extent enlargement of spleen. This is usually a milder form of disease
• Hemoglobin E leads to hemolytic anemia, microcytic blood cells and enlargement of spleen. When this variant is present along with other mutation like that of the beta thalassemia trait, it could lead to moderate to severe symptoms

• Find each type of hemoglobin in the blood. This can be used to diagnose certain types of anemia (such as thalassemia).
• Check treatment for diseases that have abnormal types of hemoglobin in the blood.
• Help couples find out how likely they are to have a child with certain forms of anemia that can be passed from a parent to a child (inherited).

You may need testing if you have symptoms of a hemoglobin disorder. These include:

• Fatigue
• Pale skin
• Jaundice, a condition that causes your skin and eyes to turn yellow
• Severe pain (sickle cell disease)
• Growth problems (in children)

If you've just had a baby, your newborn will be tested as part of a newborn screening. The screening checks for a variety of conditions. Many of these conditions can be treated if found early.

You may also want testing if you are at risk for having a child with sickle cell disease or another inherited hemoglobin disorder.

Reference values for Hemoglobin Variant Analysis   

In adults, the percentage of normal haemoglobin variants are as below.

• Hemoglobin A -     96-98%
• Hemoglobin A2 -     3-3.5%
• Hemoglobin F -     0-2%
• Hemoglobin S -     0%
• Hemoglobin D -     0%
• Hemoglobin C -     0%
• Hemoglobin (E+A2) -     0%
• Peak2 -     0-10%
• Unknown identified peak -     0-2%
• Non-specific peaks -     0-10%

Interpretation

Abnormal Hemoglobin levels that are too high or too low may mean:

The laboratory will interpret the results with a lot of care. A hematopathologist will interpret the test report. Your doctor will help interpret the test result for you and may also order additional tests like Iron Studies to arrive at a diagnosis.

High performance liquid chromatography (HPLC) is a fast and accurate method for determining the presence and for quantitation of various type of normal Hb and common abnormal Hb variants, including but not limited to Hb S, C, E, D and beta - thalassemia. The diagnosis of these abnormal Hb variants should be confirmed by DNA an              alysis. The method used has a limited role in the diagnosis of alpha thalassemia.

Slight elevation in hemoglobin A2 may also occur in hyperthyroidism or when there is deficiency of vitamin B12 or folate and this should be distinguished from inherited elevation of HbA2 in beta-thalassemia trait.