This test measures the levels of hemoglobin in the blood. Hemoglobin is a complex protein found in red blood cells. It carries oxygen to the body's organs and tissues from the lungs. It also transports carbon dioxide from the body back to the lungs. A hemoglobin test is one among st many tests that may be used to monitor or diagnose a condition called anemia. In anemia, the blood may either lack enough healthy red blood cells or enough quantity of hemoglobin