As we all know, iron is one of the most important trace elements in the human body, which is not only essential for the synthesis of hemoglobin, but also widely involved in the metabolic process of the body, and all functional cells contain iron. We all know that iron deficiency can cause damage to the body, such as iron deficiency anemia; but do you know that too much iron in the body can also cause damage to important organs and even endanger life? Iron in the body must be in a balanced state of not too much and not too little, neither lacking nor not, which is what is known as iron homeostasis in medicine. The main causes of iron deficiency are: 1, insufficient iron intake, such as long-term vegetarianism, excessive weight loss, insufficient dietary content, resulting in a negative iron balance; 2, iron absorption disorders, such as lack of gastric acid, post-gastrectomy, chronic atrophic gastritis or other gastrointestinal diseases, as well as certain drugs such as acidophilus and proton pump inhibitors, affecting the absorption of iron in food, resulting in a negative iron balance; 3, increased demand, such as during pregnancy 4, excessive iron loss, such as monthly physiological blood loss in women of childbearing age, chronic blood loss from gastrointestinal tumors or non-tumors, recurrent nosebleeds or hemoptysis, recurrent intravascular hemolysis, etc., can cause negative iron balance. Iron deficiency is a gradual process, and iron deficiency anemia occurs after the body’s iron reserves are depleted and hemoglobin synthesis is reduced. Because iron deficiency anemia develops slowly, there are often no obvious symptoms in mild anemia. It is often found by chance during routine physical examinations or blood tests for other diseases, and most patients come to the clinic with more obvious symptoms only when they develop into moderate or even severe anemia. Patients often complain of poor complexion, pallor, panic, shortness of breath, fatigue, dizziness, tinnitus, loss of appetite, memory loss, thin and brittle nails, or flattened or spatulate nails, and delayed growth in children and adolescents. Severe cases may also have xenophagia, where the patient prefers to eat things that are not food, such as dirt, lime, paper, mud, etc. The diagnosis and treatment of iron deficiency anemia are not difficult. However, it is important to emphasize that after it is clear that the anemia is caused by iron deficiency, further search for the cause of iron deficiency is necessary, especially in male adult patients. It is not uncommon for a male patient to be found to be anemic by chance, and the doctor follows the trail and finally finds out that it is a digestive tract tumor. This is because GI tumors can have recurrent, daily small amounts of GI bleeding that the patient is not aware of, and over time, iron deficiency anemia occurs; therefore, iron deficiency anemia is often the first symptom in patients with gastric or intestinal cancer. When the doctor diagnoses iron deficiency anemia, the patient must cooperate with the doctor for further examination of stool routine and occult blood, and in some cases, gastroscopy and colonoscopy, so as not to delay the detection of important diseases. Etiological treatment is the key to the treatment of iron deficiency anemia, and iron supplementation for symptomatic treatment can relieve the condition faster. There is a wide variety of iron supplements, including ferrous sulfate, ferrous succinate and ferric iron in Shanghai primary care institutions, which are more effective and have a significant increase in hemoglobin within 1 to 2 weeks and return to normal after 1 to 2 months. It should be noted that the tannic acid and polyphenols in tea and coffee will affect the absorption of iron, so do not drink more, and do not take it with iron. In addition, iron should continue to be taken for about 3 months after the hemoglobin returns to normal to replenish the body’s reserve iron. If the patient cannot tolerate oral iron or has impaired absorption in the digestive tract, injectable iron can be used, with iron dextran, iron sucrose and iron sorbitol. For patients with insufficient iron intake that causes disease, the diet should also be properly adjusted to increase the intake of animal protein. Now, let’s talk about an unfamiliar concept that is the opposite of iron deficiency and has long been overlooked – iron overload, medically known as iron overload. Our body has a strict iron metabolism regulation mechanism to ensure that the iron in our body is in iron homeostasis, the aforementioned iron deficiency is easy to understand, how does this iron overload occur? The key to iron homeostasis in the body is the balance between iron absorption in the small intestine and the body’s iron needs. In anemia and hypoxia, the body gets the “signal”: there is not enough blood and it needs to make blood. So, the small intestine compensates by absorbing more iron to meet the needs of blood production, which is the right “signal” for iron deficiency anemia, but the wrong “signal” for non-iron deficiency anemia. The excess iron absorbed is retained in the body, and the body has no other mechanism for iron excretion than blood loss during physiology and loss of iron from epithelial cells in women of childbearing age. Thalassemia, aplastic anemia, myelodysplastic syndrome, pure red blood cell aplastic anemia, and other congenital or acquired anemias can cause iron overload due to anemia and send wrong “signals”, plus the treatment of anemia requires blood transfusion, and some refractory anemias need to rely on blood transfusion. This results in a large amount of exogenous iron being deposited in the body with blood transfusions. In addition, there is a rare congenital disorder called hereditary hemochromatosis, in which the patient is not anemic, but has an iron metabolism disorder that leads to iron overabsorption and deposition in the body. Whatever the cause, excess iron in the body can be deposited in the liver, heart, spleen, pancreas, thyroid gland, pituitary gland and other vital organs, causing organ dysfunction such as cirrhosis, liver cancer, heart failure, diabetes, hypogonadism, painful muscle spasms, etc., seriously endangering health and life. The better parameters for assessing the iron content in the body are serum ferritin and transferrin saturation, and serum ferritin is also used to measure the degree of iron overload: 300-500 μg/L for mild overload, 500-1000 μg/L for moderate overload, and >1000 μg/L for severe overload. It has been found that iron overload can also occur in diseases such as malignancy, alcoholic liver disease, and chronic inflammation, and iron removal therapy will help with the treatment of the primary disease. If only iron overload is present without anemia, then intravenous bloodletting is the best treatment for iron removal. Patients with hereditary hemochromatosis need to have 400 ml of blood discharged every 1 to 2 weeks until serum ferritin drops to normal, and then 2 to 4 times a year for maintenance treatment. If the iron overload is accompanied by anemia, then obviously it cannot be treated with bloodletting and only iron chelators can be used to remove iron medically. At present, there are three types of iron chelators: desferrioxamine, desferrioxone and desferrioxylate, and only desferrioxamine and desferrioxylate are available in China. Desferrioxamine is an injectable agent, which has been marketed for half a century, with exact efficacy and low price, but because of the short half-life and cannot be taken orally, it needs continuous subcutaneous infusion or subcutaneous injection several times a day; desferrioxamine is a newly listed long-acting oral iron chelator, with the trade name Enrique, which can be taken orally once a day, with little side effects, and can be safely applied to children over 2 years old, but it is more expensive.