In this Article

• What is hemoglobin?
• How is hemoglobin measured?
• What are normal hemoglobin values?
• What does a low hemoglobin level mean?
• What does a high hemoglobin level mean?
• What is sickle cell disease?
• What is thalassemia?
• Patient Discussions: Hemoglobin - Helped With Your Diagnosis
• Hemoglobin Index

How is hemoglobin measured?

Hemoglobin is usually measured as a part of the complete blood count (CBC) from a blood sample.

Several methods exist for measuring hemoglobin, most of which are done currently by automated machines designed to perform several different tests on blood. Within the machine, the red blood cells are broken down to get the hemoglobin into a solution. The free hemoglobin is exposed to a chemical containing cyanide which binds tightly with the hemoglobin molecule to form cyanmethemoglobin. By shining a light through the solution and measuring how much light is absorbed (specifically at a wavelength of 540 nanometers), the amount of hemoglobin can be determined.

What are normal hemoglobin values?

The hemoglobin level is expressed as the amount of hemoglobin in grams (gm) per deciliter (dl) of whole blood, a deciliter being 100 milliliters.

The normal ranges for hemoglobin depend on the age and, beginning in adolescence, the gender of the person. The normal ranges are:

• Newborns: 17-22 gm/dl
  
  
• One (1) week of age: 15-20 gm/dl
  
  
• One (1) month of age: 11-15gm/dl
  
  
• Children: 11-13 gm/dl
  
  
• Adult males: 14-18 gm/dl
  
  
• Adult women: 12-16 gm/dl
  
  
• Men after middle age: 12.4-14.9 gm/dl
  
  
• Women after middle age: 11.7-13.8 gm/dl

All of these values may vary slightly between laboratories. Some laboratories do not differentiate between adult and "after middle age" hemoglobin values.

What does a low hemoglobin level mean?

A low hemoglobin is referred to as anemia. There are many reasons for anemia.

Some of the more common causes are:

• loss of blood (traumatic injury, surgery, bleeding colon cancer or stomach ulcer),
  
  
• nutritional deficiency (iron, vitamin B12, folate),
  
  
• bone marrow problems (replacement of bone marrow by cancer,
  
  
• suppression by chemotherapy drugs,
  
  
• kidney failure), and
  
  
• abnormal hemoglobin (sickle cell anemia).

Hemoglobin - Helped With Your Diagnosis

The MedicineNet physician editors ask:

Please describe how Hemoglobin has helped in your diagnosis.

Anonymously share your comment to help others.
See 13 Viewer Comments

Submit Your Comment

Suggested Reading by Our Doctors

• epoetin alfa, Epogen, Procrit - Explains the medication epoetin alfa (Epogen, Procrit), a drug used to treat anemia (low red blood cell count) that is associated with chronic kidney failure in patients who are or will be receiving renal dialysis.
• Complete Blood Count (CBC) - A complete blood count (CBC) measures the concentration of white blood cells, red blood cells, and platelets in the blood and aids in the diagnosis of conditions and diseases such as anemia, malignancies, and immune disorders.
• Kidney Failure - Learn about kidney failure, in which the body has fluid retention, risen blood pressure, toxin build up and lack of red blood cells. Symptoms include fatigue, nausea, and apetite loss.

Read more Hemoglobin related articles »

Latest Medical News

• Anemia Drugs May Cause Deadly Blood Clots
• Diabetes May Affect Women's Heart Rhythm
• Patients Not Always Told of Lab Results
• Effect of Strict Diabetes Control on Heart Still Unclear