Each unit of blood contains about 200mg to 250mg of iron. Long-term transfusion patients have an average of about 0.4mg to 0.5mg/kg/d of extra iron per day, and probably after 10 to 20 transfusions patients develop iron overload, and generally need to start iron removal therapy after 1 year or after 50 transfusions of red blood cells.
Iron overload due to long-term transfusion with parenchymal tissues, such as liver and heart, fibrosis and functional impairment is hemochromatosis, and if only tissues contain ferric heme deposits, it is hemochromatosis with ferric heme deposits. Post-transfusion hemochromatosis occurs usually with a transfusion volume of 10,000 ml or more, involving tissues such as liver, heart, skin, pancreas and other endocrine glands, leading to cirrhosis, liver fibrosis, hepatocellular carcinoma, heart failure, diabetes mellitus, infertility and growth inhibition.
Evaluation.
① Serum ferritin measurement, which is easy to detect, can indirectly respond to the body’s iron load, and serum ferritin levels >2500 μg/L are significantly associated with heart failure. However, serum ferritin levels fluctuate widely and are susceptible to infection, inflammation, tumors, liver disease and alcohol abuse.
Liver biopsy, the “gold standard” for the diagnosis of hemochromatosis, can directly measure liver iron levels, can be quantified, has good specificity and sensitivity, and provides results of histological and pathological changes in the liver. However, liver biopsy is invasive and needs to be performed by experienced clinicians.
Iron removal is recommended for patients with MDS as follows.
① transfusion-dependent MDS with good prognosis: IPSS low or intermediate risk-1 group, or RA, RARS and 5q- syndrome in WHO staging, and
a Serum ferritin over 1,000 ng/ml
b Those who are to undergo allo-HSCT
c or whose survival expectation exceeds 1 year
② MDS in transfusion-dependent high-risk groups with poor prognosis (IPSS intermediate-risk-2 and high-risk groups).
a Serum ferritin over 1,000 ng/ml and proposed for allo-HSCT
b Serum ferritin more than 1 000 ng/ml and survival expectation more than 1 year
(iii) Transfusion-dependent patients with ICT started in
a with evidence of iron-induced organ damage
b or serum ferritin over 1 000 ng/ml and fasting transferrin over 0.5, not counting the amount of red blood cells transfused.
Treatment: The evaluation of iron overload mainly applies serum ferritin measurement, which is easy to detect and can indirectly respond to the body’s iron load. Serum ferritin levels >2500 μg/L are significantly associated with heart failure, and overall survival decreases in those with MDS ferritin reaching 1000 μg/L. Iron removal therapy must be performed, and the general treatment goal is also to reduce ferritin to below 1000 μg/L.
①Deferrioxamine (deferrioxamine) dose 20mg-60mg/kg/d by intravenous infusion, excretion of iron through urine and stool, can effectively reduce iron stores to normal or near normal levels, deferrioxamine is currently the only drug with evidence of reversal of heart failure due to iron overload. Ferritin levels are measured every 3 months, and liver iron levels are evaluated annually. Deferoxamine is ocular, otologic and osteo-toxic; annual eye exams and hearing tests should be performed. myocardial iron levels should be evaluated annually after age 10.
②Dose of deferiprone (deferiprone) 50mg-100mg/kg/d, orally, excretes iron through urine and has a stronger effect on myocardial iron, while deferoxamine has a better effect on hepatic iron, so deferoxamine and deferiprone can be used in combination. Deferiprone has a risk of granulocyte deficiency, and weekly blood tests for a white blood cell sorting count are recommended.
Deferiprone may also cause gastrointestinal reactions, joint symptoms, and transient ALT elevation. ALT is measured monthly for the first 3 to 6 months after dosing, and then every 6 months thereafter. Ferritin levels were measured every 3 months and liver iron levels were evaluated annually. myocardial iron levels were assessed annually after age 10.
Below a dose of 75 mg/kg/d, negative iron balance was not achieved in all patients.