A hemoglobin test is used to find out how much hemoglobin is in your blood. It is most often used to determine if you have low levels of red blood cells, which is a condition known as anemia. In addition to identifying anemia, a hemoglobin test can be involved in the diagnosis of other health problems like liver and kidney disease, blood disorders, malnutrition, some kinds of cancer, and heart and lung conditions. For people who have been treated for anemia or other conditions that can affect hemoglobin levels, a hemoglobin test may be ordered in order to check their response to treatment and monitor the progression of their overall health. The erythrocyte sedimentation rate, also known as ESR, is based on how quickly red blood cells (RBCs) settle inside a test tube. An ESR test is used to assess inflammation in the body. Many conditions can cause an abnormal ESR, so an ESR test is typically used with other tests to diagnose and monitor different diseases.