Hemoglobin or Hb Test | A Complete Overview

Hb Test

Hb test

Hb test or Hemoglobin test is routinely measured as separate or under CBC (Complete blood count) test. A Hemoglobin blood test sample of a patient is treated chemically by the automated machine to obtain hemoglobin from red blood cells(RBC).

This hemoglobin forms a compound after bounding chemically with cyanide, that absorbs light. The absorbed amount of light represents the amount of hemoglobin present in the blood. But What is hemoglobin or Hb test?

What Is Hemoglobin?

what is hemoglobin


Hemoglobin or Hb meaning is same. Hemoglobin is a complex protein found in RBC that contains an iron molecule. The main function of hemoglobin is to carry carbon dioxide from body tissues to the lungs and exchange it with oxygen, and then carry back oxygen to body tissues.

The iron molecule in hemoglobin helps maintain the structure of red blood cells.

What Is The Normal Hemoglobin Level?

The hemoglobin normal ranges that is widely accepted by a doctor is as follows:

Birth 13.5 to 24.0 g/dl mean 16.5 g/dl
Age <1 month: 10.0 to 20.0 g/dl mean 13.9 g/dl
Age 1-2 months: 10.0 to 18.0 g/dl mean 11.2 g/dl
Age 2-6 months: 9.5 to 14.0 g/dl mean 12.6 g/dl
Age 0.5 to 2 years: 10.5 to 13.5 g/dl mean 12.0 g/dl
Age 2 to 6 years: 11.5 to 13.5 g/dl mean 12.5 g/dl
Age 6-12 years: 11.5 to 15.5 g/dl mean 13.5 g/dl
  • Female
Age 12-18 years: 12.0 to 16.0 g/dl mean 14.0 g/dl
Age >18 years: 12.1 to 15.1 g/dl mean 14.0 g/dl
  • Male
Age 12-18 years: 13.0 to 16.0 g/dl mean 14.5 g/dl
Age >18 years: 13.6 to 17.7 g/dl mean 15.5 g/dl


What Is Anemia?

what is anemia

When a person’s hemoglobin level is below the lowest limits of normal as according to their age and sex (see above the hemoglobin normal range of values) is known as hemoglobin Low or Anemia.

For example, a 21-year-old male would have low hemoglobin levels or called Anemic if his Hb test value is below 13.6 g/dl.

Causes Of Anemia

Some of the more common causes of anemia are as follows:

  • Nutritional (iron, folic acid, or vitamin B 12 deficiency [pernicious anemia]
  • Gastrointestinal blood loss (ulcers, colon cancer)
  • Kidney problems
  • Blood loss (from trauma or surgery)
  • Red Blood cell synthesis problems (bone marrow disorders, genetic disorders such as sickle cell anemia)
  • Bone marrow suppression by chemotherapy or radiation exposure

Anemia Or Low Hemoglobin Symptoms

Anemia word is obtained from Greek term anaimia, meaning lack of blood. If Hemoglobin low levels found in Hb test, it shows low hemoglobin symptoms that may be a sign of:

  • Different types of anemia
  • Thalassemia
  • Iron deficiency
  • Liver disease
  • Cancer and other diseases
  • Pale skin
  • Weakness
  • Shortness of breath
  • Fainting
  • Palpitation
  • Chest Pain
  • Restless legs syndrome

How To Increase Hemoglobin Levels?


Rich iron & folic acid edibles such as apple, meat, egg, fish, green vegetables adding to your diet may help in increasing hemoglobin level. If the Hb level is below 7g/dl, you will need iron supplements prescribed by your doctor.

If the Hb level is below 4g/dl, your doctor might suggest you a blood transfusion.

Hemoglobin High:

Hemoglobin high levels in Hb test means that measured hemoglobin levels of the patient are above the upper limits of normal value for the age and sex of the person (see above tables normal values).

For example, a 21-year-old boy’s Hb test value that has detected above 17.7 g/dl would have considered a high hemoglobin level.

High Hemoglobin Causes

Causes Of High Hemoglobin

Some causes of high hemoglobin levels are as follows:

  • Living at a high altitude
  • Lung disease (Emphysema, COPD)
  • Cancer
  • Tobacco smoking
  • Bone marrow disorders
  • Overdose or inappropriate use of the drug Epoetin alfa
  • Blood doping (increasing RBC’s by using certain drugs)

Side Effects Of High Hemoglobin Levels

Side Effects Of High Hemoglobin Levels

If Hb test finds High hemoglobin in blood, its called polycythemia. Polycythemia vera is a disorder in which your body makes too many red blood cells. It can cause headaches, fatigue, and shortness of breath.

Polycythemia causes a Blood clot (thrombosis) that may lead to heart attacks, strokes, clots in the legs or lungs, or clots in arteries. These events are considered the major causes of death.

Besides this the other diseases may cause due to hemoglobin high level of blood are:

  • Lung disease
  • Heart disease

How To Treat High Hemoglobin?

In the treatment of polycythemia, a commonly recommended medication is hydroxyurea (Hydrea). This is especially advised for those people who are at risk for clot formation. At above age 70, hydroxyurea is favorable in both cases:

  1. Thrombocytosis (Increased platelet count, greater than 1.5 million) and
  2. Cardiovascular disease.

A more favorable drug used to lower the risk of clotting (thrombotic) events is Asprin. But it is generally avoided in the people having any bleeding history.

Ideal Hemoglobin Level In Pregnancy

Ideal Hemoglobin Level In Pregnancy

It is quite common to fall hemoglobin levels during pregnancy. This is due to body needs the extra nutrients for baby’s development, the blood volume increases by 50% and thus lowering the hemoglobin level (concentration).

It starts to increase around the 8th week of pregnancy. So it is advisable to maintain the ideal hemoglobin level in pregnancy between 12 and 15g/dl.  Source: https://www.emedicinehealth.com/hemoglobin_levels/page2_em.htm



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