Haemoglobin is a very essential component of your blood. Its main function is to help carry oxygen from your lungs to the cells of your organs. This provides the cell with energy to perform their functions optimally. A low haemoglobin level can also lead to extreme fatigue, bruising easily, fainting spells and in some cases lack of blood clotting. Usually a low hemoglobin count is due to deficiency in iron, however, there my be other reasons for it too, like excessive dieting, living an unhealthy lifestyle, some diseases and cancers. It is essential that you visit a doctor to get a more accurate diagnosis of the cause.