Hemoglobin is a complex molecule found in red blood cells. Part of the molecule is protein and the other part, known as a porphyrin, contains an iron atom which can bind and carry oxygen. The iron in hemoglobin is responsible for the red color of blood.
Often, this test is part of a complete blood count (CBC). It may also be done: during pregnancy during infancywhen a person has symptoms of anemia, such as lack of energy, pale skin, and shortness of breath to measure progress when a person is being treated for anemia when family history or ethnic or racial background puts a person at risk for a blood disorder, such as sickle cell disease or thalassemia.
Blood for the test is usually taken from a person's forearm. First, a tight band is put on the upper arm to make the veins swell below it. An area of skin on the forearm over the vein chosen is cleansed.
A needle is inserted into the vein and a sample of blood is collected in a tube. Occasionally blood is taken from another site, such as a finger or heel. If so, the skin is cleansed and pricked with a sharp tool called a lancet. Drops of blood are collected in a tiny tube and analyzed in a laboratory.
Generally, no preparation is needed.
Age, sex, and other factors cause normal ranges for hemoglobin to vary. Generally, healthy test ranges are: newborns - 14 to 20 grams of hemoglobin per deciliter of blood (g/dl)children 6 months to 6 years -- 9.5-14 g/dlchildren 6 to 18 years - 10 to 15.5 g/dlmen 18 or older - 14 to 18 g/dlwomen 18 or older -12 to 16 g/dlpregnant women -- at least 11 g/dl
A low hemoglobin level generally means that a person's overall supply of red cells is low, a condition known as anemia.
The many common causes of anemia include: excessive menstrual bleeding in womengastrointestinal bleeding, such as that from bleeding peptic ulcers and colon cancer malnutrition increased nutritional needs, which occurs during rapid growth periods of childhood and in pregnancy inherited causes, such as sickle cell disease, a condition in which red cells are misshaped because of an abnormal hemoglobin molecule
An increased hemoglobin level can occur for several reasons. Common causes include: dehydration. The hemoglobin concentration is high in the blood sample simply because the person has lost blood fluid volume. The hemoglobin value will normalize once the person is re-hydrated.chronic obstructive pulmonary diseases, such as emphysema, which is usually due to smoking cigarettes blood cancer, such as a cancer called polycythemia vera
Depending on the result of this test and its suspected cause, the healthcare professional may recommend treatment or further testing.
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