Hemoglobin (Hgb)

The Hemoglobin (Hgb) test contains 1 test with 1 biomarker.

Description: A Hemoglobin (Hgb) test is a blood test that measures the amount of hemoglobin your red blood cells contain.

Also Known As: Hb Test, Hgb Test

Collection Method: Blood Draw

Specimen Type: Whole Blood

Test Preparation: No preparation required

When is a Hemoglobin test ordered?

The hemoglobin test may be requested as part of a general health assessment or when a person exhibits signs and symptoms of a red blood cell disorder such as anemia or polycythemia.

When someone has been diagnosed with recurrent bleeding difficulties, chronic anemias, or polycythemia, this test may be done numerous times or on a regular basis to check the effectiveness of treatment. It's also possible that it'll be ordered on a regular basis for those having therapy for cancers that are known to harm the bone marrow.

What does a Hemoglobin blood test check for?

Hemoglobin is an iron-containing protein found in all red blood cells, which gives them their distinctive red color. RBCs use hemoglobin to bind to oxygen in the lungs and transport it to tissues and organs all over the body. It also aids in the movement of a little amount of carbon dioxide, which is a byproduct of cell metabolism, from tissues and organs to the lungs, where it is exhaled.

The hemoglobin test determines how much hemoglobin is present in a person's blood sample. To swiftly assess an individual's red blood cells, a hemoglobin level can be used alone or in conjunction with a hematocrit, a test that assesses the fraction of blood made up of RBCs. Red blood cells, which account for roughly 40% of the amount of blood, are created in the bone marrow and released into the bloodstream when they are mature, or nearly so. RBCs have a 120-day lifespan, and the bone marrow must constantly manufacture new RBCs to replace those that have aged and degraded or have been lost due to hemorrhage.

RBCs, and thus the level of hemoglobin in the blood, can be affected by a variety of diseases and situations. When the quantity of red blood cells grows, the hemoglobin level and hematocrit both rise. When the synthesis of RBCs by the bone marrow decreases, RBC destruction increases, or blood is lost owing to hemorrhage, the hemoglobin level and hematocrit fall below normal. Anemia is a disorder in which the body's tissues and organs do not acquire enough oxygen, causing exhaustion and weakness. It is caused by a decline in RBC count, hemoglobin, and hematocrit. Polycythemia occurs when the body produces too many RBCs, causing the blood to thicken, resulting in sluggish blood flow and other complications.

Lab tests often ordered with a Hemoglobin test:

  • Complete Blood Count (CBC)
  • Hematocrit
  • Red Blood Cell Count (RBC Count)
  • Blood Smear
  • Iron Total
  • Ferritin
  • Reticulocyte Count
  • Vitamin B12
  • Folate
  • Red Cell Indices
  • G6PD
  • Erythropoietin
  • Hemoglobinopathy Evaluation

Conditions where a Hemoglobin test is recommended:

  • Anemia
  • Sickle Cell Anemia
  • Thalassemia
  • Myeloproliferative Neoplasms
  • Hemoglobin Abnormalities
  • Bone Marrow Disorders

How does my health care provider use a Hemoglobin test?

Anemia is commonly detected with a hemoglobin test in conjunction with a hematocrit or as part of a complete blood count. The test can be used to detect, diagnose, or track a variety of illnesses and disorders that impact red blood cells and/or hemoglobin levels in the blood. All red blood cells include hemoglobin, an iron-containing protein that allows RBCs to bind to oxygen in the lungs and transport it to tissues and organs throughout the body.

A hemoglobin test can be used for a variety of purposes, including:

  • Anemia and polycythemia are diagnosed, diagnosed, and measured.
  • Assess the patient's reaction to anemia or polycythemia treatment.
  • If the anemia is severe, you can help make decisions about blood transfusions or other therapies.

Some factors influence RBC production in the bone marrow, resulting in an increase or decrease in the quantity of mature RBCs discharged into the bloodstream. The longevity of RBCs in the circulation can be influenced by a variety of factors. The overall amount of RBCs and hemoglobin will diminish if there is greater destruction of RBCs or loss of RBCs through bleeding, and/or the bone marrow is unable to make new ones quickly enough, leading in anemia.

This test can tell you if you have an issue with red blood cell production or longevity, but it can't tell you what's causing it. A blood smear, reticulocyte count, iron studies, vitamin B12 and folate levels, and, in more severe cases, a bone marrow examination are some of the other tests that may be conducted at the same time or as follow-up to establish a reason.

What do my Hemoglobin test results mean?

Because hemoglobin levels are frequently measured as part of a complete blood count, the results of other components are taken into account. Hemoglobin levels must be interpreted in conjunction with other indicators such as RBC count, hematocrit, reticulocyte count, and/or red blood cell indices when they rise or fall. Other characteristics to consider are age, gender, and race. Hemoglobin reflects the RBC count and hematocrit results in general.

Anemia is defined as a low hemoglobin level combined with a low RBC count and a low hematocrit. Among the causes are:

  • Excessive blood loss-as a result of severe trauma or continuous bleeding from the digestive tract, bladder, or uterus.
  • Iron, folate, or B12 deficiency are examples of nutritional inadequacies.
  • Toxins, radiation, chemotherapy, infection, and medicines can all cause damage to the bone marrow.
  • Myelodysplastic syndrome, aplastic anemia, or tumors of the bone marrow, such as lymphoma, leukemia, multiple myeloma, or other cancers of the bone marrow
  • Renal failure—severe and chronic kidney illnesses cause the kidneys to produce less erythropoietin, a hormone that drives RBC synthesis in the bone marrow.
  • Inflammatory diseases or disorders that last a long time
  • Hemoglobin production is reduced.
  • Excessive destruction of red blood cells, such as hemolytic anemia caused by autoimmunity or faults in the red blood cell itself, such as hemoglobinopathy, RBC membrane abnormalities, or RBC enzyme.

Polycythemia is defined as a high hemoglobin level combined with a high RBC count and hematocrit. Among the causes are:

  • Lung disease-when a person's body is unable to breathe in and absorb enough oxygen. As a result, the body produces more red blood cells to compensate.
  • Congenital heart disease—in some cases, an improper connection between the two sides of the heart occurs, resulting in lower blood oxygen levels. The body responds by creating extra red blood cells in an attempt to compensate.
  • Excess erythropoietin-producing kidney tumors
  • Hemoglobin levels in heavy smokers are higher than in nonsmokers.
  • Genetic factors
  • Having to live at a high altitude
  • Dehydration causes hemoglobin to rise unnaturally when the volume of liquid in the blood declines.
  • Polycythemia vera-a rare condition in which the body creates too many RBCs.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Also known as: Hb, Hemoglobin Hgb, Hgb


Serum hemoglobin is a blood test that measures the level of free hemoglobin in the liquid part of the blood (the serum). Free hemoglobin is the hemoglobin outside of the red blood cells. Most of the hemoglobin is found inside the red blood cells, not in the serum.
*Process times are an estimate and are not guaranteed. The lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.

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