what is hgb in blood test

A hemoglobin test measures the amount of hemoglobin in your blood. Hemoglobin is a protein in red blood cells that carries oxygen from your lungs to the rest of your body and transports carbon dioxide from your organs and tissues back to your lungs. The test is often done as part of a complete blood count (CBC) to check for anemia, a condition in which your body has fewer red blood cells than normal. If a hemoglobin test reveals that your hemoglobin level is lower than normal, it means you have a low red blood cell count (anemia) . Anemia can have many different causes, including vitamin deficiencies, bleeding, and chronic diseases. If a hemoglobin test shows a higher than normal level, there are several potential causes, such as the blood disorder polycythemia vera, living at a high altitude, smoking, and dehydration.