Iron Status in Infants with HDFN
Iron is contraindicated for infants with HDFN unless a ferritin test shows a true deficiency.
Normal Lab Values: 25-200 ng/mL for newborns. 50-200 ng/mL for 1-5 months of age.
One of the common misconceptions is that babies with HDFN need iron supplements to fix their anemia. This is false. Iron supplements will not help infants with Hemolytic Disease of the Fetus and Newborn (HDFN), and can actually be dangerous in some instances. Regardless of the specific antibody (anti-D, anti-K, anti-c, anti-E, etc), the infant can still be at risk. Medical literature has shown that infants with HDFN do not have iron deficiency anemia, but hemolytic anemia. When the red blood cells are destroyed by the antibodies, the iron in the baby’s blood is stored in the body and recycled, leading to a build up of iron and iron overload for the majority of babies with HDFN. “Iron therapy is contraindicated in most cases of hemolytic anemia. The reason is that iron released from RBCs in most hemolytic anemias is reused and iron stores are not reduced 1.” Infants with hemolytic anemia have normal iron stores, or high iron stores if they have had an intrauterine transfusion (IUT). One study found that 70% of babies with HDFN had iron overload at birth and none were iron deficient at birth. At 1 month of age, 50% of the infants still had iron overload, and 18% continued to have iron overload at 3 months 2. It is not just babies who have received IUTs who are at risk. “In addition to transfusions for alloimmune HDFN, the haemolysis itself can also contribute to iron overload in alloimmune HDFN 2“. Multiple articles say that babies with HDFN are at risk for iron overload and should not be supplemented without a ferritin test first. “Therefore, we advise to measure iron status, and we discourage the use of iron supplementation in the first 3 months of life in neonates with alloimmune HDFN 2“. Some authors suggest that all babies who have received IUTs be evaluated for high ferritin levels 3. If the ferritin does come back highly elevated, chelation therapy may be used to reduce the amount of iron in the blood and to reduce or reverse liver damage 4, 5. Inappropriate administration of iron in infants with HDFN can result in iron overload 9 and adverse events such as cholestasis 16, portal hypertension, coagulopathy abnormal liver enzymes, free-radical damage 17, liver damage, or death.
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Treatments for Anemia
Elevated levels of circulating maternal antibodies in the neonatal circulation in conjunction with suppression of the fetal bone marrow production of red cells often results in the need for neonatal red cell “top-up” transfusions after discharge from the nursery. This results in a 1- to 3-month period in which up to 75% of these infants may need “top-up” red cell transfusions6. Weekly reticulocyte counts and hematocrit levels should be assessed until a rising reticulocyte count is noted for at least 2 consecutive weeks. The threshold-for-transfusion includes a hematocrit value of less than 30% in the symptomatic infant or less than 20% in the asymptomatic infant have been suggested by some experts. Typically, only one neonatal transfusion is required, although a maximum of up to three has been reported.
Erythropoietin has been in use since the 1990s as an adjunct treatment for late anemia and to increase a reduced reticulocyte count. In limited single-arm studies and case reports, erythropoietin has been shown to be safe 7, 8 and may reduce the need for transfusion in neonates with HDFN 9, 10, 11, 12, 13. In one 6-week study of 20 infants with HDFN due to anti-D, the “number of erythrocyte transfusions was significantly lower than that of the control group (1.8 versus 4.2). The reticulocyte counts and Hb levels rose earlier in the treatment group” 14. This may also be a treatment option for children whose parents object to the use of blood products for religious reasons 15. For additional articles relating to erythropoietin, see our additional reading by topic page.
Active hemolysis consumes folate; folate is a key ingredient in erythropoiesis. As a result, folic acid is frequently prescribed for infants with HDFN in order to encourage the creation of new RBCs. Various approaches supplement folic acid at a dosage between 50 µg/day and 300µg/day for 3 months 16.