Hemoglobin Test-Why am I having this test?

Hemoglobin test may be done to check for anemia, a condition in which you have a reduced number of red blood cells. Hemoglobin is the portion of the red blood cell that carries oxygen and carbon dioxide. Various types of anemia can cause your hemoglobin level to be low. It may also be low if you:

• Have certain diseases, such as cancer.
• Have nutritional problems.
• Have had severe bleeding.

What is being tested?

This test measures the total amount of hemoglobin in your blood.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel.

Tell a health care provider about:

• All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
• Whether you are pregnant or may be pregnant.

How are the results reported?

Your test results will be reported as values. Your health care provider will compare your results to normal ranges that were established after testing a large group of people (reference ranges). Reference ranges may vary among labs and hospitals. For this test, common reference ranges are:

Adults

• Male: 14–18 g/dL or 8.7–11.2 mmol/L (SI units).
• Female: 12–16 g/dL or 7.4–9.9 mmol/L (SI units).
• Pregnant female: greater than 11 g/dL or 6.8 mmol/L (SI units).
• Elderly:
  • Male: 12.4–14.9 g/dL or 7.7–9.2 mmol/L (SI units).
  • Female: 11.7–13.8 g/dL or 7.2–8.5 mmol/L (SI units).

Children

• Newborn: 14–24 g/dL.
• 0–2 weeks old: 12–20 g/dL.
• 2–6 months old: 10–17 g/dL.
• 6 months to 1 year old: 9.5–14 g/dL.
• 1–6 years old: 9.5–14 g/dL.
• 6–18 years old: 10–15.5 g/dL.

What do the results mean?

Results within the reference range are considered normal. A hemoglobin level that is too high may indicate any of the following:

• Having too many red blood cells (erythrocytosis).
• A disorder of the bone marrow (polycythemia vera).
• Severe dehydration.

A hemoglobin level that is too low may indicate any of the following:

• Low red blood cell count (anemia).
• A disorder that affects the formation of hemoglobin (hemoglobinopathy).
• Chronic liver disease (cirrhosis).
• A condition where red blood cells are destroyed more often than usual (hemolytic anemia).
• Active bleeding (hemorrhage).
• Bone marrow failure.
• Kidney disease.
• Various types of cancer.
• Enlarged spleen.

Certain conditions may also cause your hemoglobin level to be slightly lower or higher.

• It may be slightly low in conditions such as:
  • Normal pregnancy.
  • Dietary deficiency.
  • Some autoimmune diseases.
  • Replacement heart valves (prosthetic valves).
• It may be slightly high in conditions such as:
  • Congenital heart disease.
  • Smoking or lung disease such as chronic obstructive pulmonary disease (COPD).
  • Living at high altitudes.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?

Summary

• The hemoglobin test may be done to check for anemia, a condition in which you have a reduced number of red blood cells.
• Hemoglobin levels that are lower than normal can be seen in many conditions, including certain cancers, dietary deficiencies, and severe bleeding.
• Hemoglobin levels that are higher than normal can be seen in COPD, congenital heart disease, polycythemia vera, erythrocytosis, and severe dehydration.
• Talk with your health care provider about what your results may mean.