HB or Hemoglobin refers to a complex protein present in the red blood cells of human beings, which contain iron molecules. It primarily carries oxygen to tissues of a human body from his lungs and exchanges oxygen for carbon dioxide, while carries it back to lungs to allow its exchange for oxygen. In addition, hemoglobin constitutes an iron-containing protein presents usually in red blood cells, which allows RBCs in binding of the oxygen within the lungs and carry it to various other organs and tissues in the entire body. Hemoglobin test intends to detect the problem of anemia in combination with hematocrit or a part of CBC i.e. complete blood count.