Analysis: Blood test: Hemoglobin {Process} 8 Steps of the Blood test

Analysis: Blood test: Hemoglobin {Process} 8 Steps of the Blood test

Hemoglobin is the protein in red blood cells. Its analysis and quantification by blood tests may be useful in better understanding the health status of some patients.

Hemoglobin fixes oxygen carries it into the bloodstream and delivers it to the body’s cells to ensure their proper functioning. It contains iron and gives the blood its red color.

What does the doctor analyze?

The hemoglobin level allows us to assess a possible change in the number of red blood cells and, as a result, the oxygenation capacity of the tissues. This value can be used to diagnose a condition of red blood cells: anemia or, conversely, polycythemia.

A specific examination, electrophoresis of hemoglobin, can detect hereditary malformations of hemoglobin – sickle cell disease and thalassemias – that cause chronic anemia.

How do they prepare?

The examination is prescribed by a doctor during a consultation or in the hospital. This can be done on an even day or not.

It is essential to verify that the medical analysis laboratory can perform this examination by calling beforehand. When you go to your appointment, bring your prescription order, social security cards, and mutual insurance.

 What is the test?

Measuring hemoglobin requires the removal of a blood tube after setting up a tourniquet. The amount of blood required for this examination is very small and it is possible for toddlers to use a few drops of blood collected at the heel.

On average, results are available within 24 hours of sampling.

What are the possible complications?

After the sample, press the puncture point for a few minutes, avoiding bending the elbow to limit the risk of hematoma. But even when they exist, these puncture-point hematomas are perfectly benign and resolve within a few days.

So, what next?

You can feed yourself as soon as you leave the lab and resume normal activity, even if you feel that the number of tubes taken was important. Each tube contains only about 5ml of blood.

The test results are delivered within days of the completion of the exam in the form of a letter. It is necessary to inform the prescribing physician of these results because he alone is in a way to decide on a possible treatment or the completion of further examinations.

Even if a result appears to be normal, your doctor should be informed.

How would be the result?

The normal values ​​for hemoglobin, in g / dL, are as follows,

Women: 12 – 16 g / dl (about 7.5 – 9.9 mmol / l)
Men: 13.5 – 17.5 g / dl (about 8.4 – 10.9 mmol / l)

What are the causes for too high level of hemoglobin?

If the patient has too many red blood cells in the blood ( Polyglobulie /erythrocytosis), this is shown by an increased Hb-value. A build-up of red and white blood cells and platelets also leads to a value above the norm. Too high a hemoglobin value occurs in people who have stayed at high altitudes for a long time. Sometimes an increased hemoglobin level can also be observed in smokers. Dehydration can lead to elevated values.

What are the consequences of lowering hemoglobin?

Anemia occurs when hemoglobin levels are less than 14 g/dL in newborns, 12 g/dL in women or children. Anemia results in a decrease in the oxygenation capacity of the cells and possibly, depending on its degree, causing paleness, shortness of breath, or even chest pain.

There are different types of anemias that are classified according to the size of red blood cells (micro or macrocytic) and the presence or not of reticulocytes that are the precursors of red blood cells.

The main causes of anemia are deficiencies (iron, folate or vitamin B12), excess destruction of red blood cells (hemolysis) and bone marrow diseases that produce red blood cells (medullary deficiency).

Hemoglobin in urine

Hemoglobin can also be detected in the urine when red blood cells “die” en masse in the body. The hemoglobin can then no longer be properly broken down and utilized by the organism and is excreted by the kidneys with the urine.

The urine then turns dark red. This process, called hemoglobinuria, can occur in rare autoimmune diseases, malaria, certain forms of anemia, and transfusion errors. It is not to be confused with blood in the urine (hematuria), whereby red blood cells and other blood components are detected in the urine.

The Hb value is subject to fluctuations in every person. Time of day, body position, laboratory method and how blood is taken influence the value. In addition, the blood laboratories issue different reference ranges for the Hb value, sometimes in different units of measurement. All these factors will be taken into account by the doctor when interpreting the hemoglobin value and further diagnosis.

Reference: WHO: Handbook: The clinical use of blood, Geneva, 2002; Institute for Transfusion Medicine, University of Leipzig:, retrieved September 2015