Hemoglobin (HGB, Hb)
Hemoglobin is an iron-containing red pigment. Blood is red because it contains hemoglobin that binds oxygen.
Apart from giving blood its red color, hemoglobin can form unstable bonds with oxygen enabling red blood cells to deliver oxygen to all body organs and tissues.
The air contains oxygen. When it gets into the lungs, oxygen molecules are taken up by hemoglobin that flows through the body’s blood vessels transportingthis oxygen to all cells of the body.
When an oxygen molecule is delivered to its cell, hemoglobin removes a molecule of carbon monoxide from it. Then the red blood cell moves back to the lungs carrying the carbon monoxide molecule. The carbon monoxide is released from the body during exhalation, and a new oxygen molecule is picked up. After that, the red blood cell moves further to deliver this oxygen to a new cell.
Elevated levels of hemoglobin may be caused by exercise, erythrocytosis, hemoconcentration, congenital heart disease.
A medical condition in which hemoglobin is lower than normal is called anemia. Low hemoglobin levels can result from bleeding, blood disorders, blood transfusion, or vitamin deficiency (B12, folic acid).
A low hemoglobin count is common in pregnant women. Low hemoglobin levels may be caused by iron deficiency because the recommended daily intake of iron is higher for pregnant women.