Hematological diseases primarily affect the blood and blood-forming organs. Examples include anemias like iron deficiency anemia, which occurs when the body does not have adequate iron. Iron is necessary for red blood cell formation to produce hemoglobin. Without enough iron, the body cannot produce sufficient hemoglobin in red blood cells to adequately deliver oxygen to tissues, which can cause anemia. Iron deficiency is commonly caused by blood loss, failure to meet increased iron requirements during growth or pregnancy, or inadequate iron absorption from the diet or gastrointestinal issues. Symptoms include pale skin, fatigue, and shortness of breath. Iron deficiency is treated with oral or intravenous iron supplements to restore iron levels.