Conditions such as Hodgkin's disease, cirrhosis of the liver and different types of anemia can cause low hemoglobin levels, as stated by Mayo Clinic. Pregnancy, kidney disease, certain medications and lead poisoning can cause low hemoglobin levels as well.
Inflammatory diseases in general also cause hemoglobin levels to drop, as noted in the Journal of Clinical Oncology. Cirrhosis and other chronic liver diseases cause anemia because they put patients at risk for gastrointestinal bleeding, according to the World Journal of Gastroenterology. This bleeding happens because the blood in the damaged liver no longer coagulates properly. Hepatitis may also lead to aplastic anemia, in which the bone marrow no longer produces enough red blood cells. Liver diseases can also cause the spleen to enlarge, as stared by WebMD. An enlarged spleen may destroy too many blood cells.
Thalassemia is a genetic condition in which an individual produces less hemoglobin than normal, as noted by Mayo Clinic. There are different types of this disease, and for some people, the symptoms are so mild that they do not need aggressive treatment. Other patients need to have regular blood transfusions. The signs and symptoms of thalassemia usually present when the patient is very young.