HDFN & Low Neutrophils

Fast Facts

Neutropenia: A reduced level of neutrophils, a specialized kind of white blood cell.

Normal Lab Values: 6-26 x 10 9/L for newborns. Decreases to 1-9 x 10 9/L at 1 month of age.

Neutropenia as a result of maternal alloimmunization has been documented since 1960 and still occurs in 45% of infants with HDFN 1 today. Neutropenia can develop with any antibody including and not limited to: anti-D, anti-K, anti-c, anti-E. The child’s body is so busy producing red blood cells to compensate for the ones destroyed by the antibodies, that it simply does not produce other blood cells including white blood cells (neutrophils), and platelets (thrombocytes) 2. This can lead to neutropenia – a low level of neutrophils. In addition to neutropenia, leukopenia has also been known to occur 3. While all hydropic infants in Koenig’s paper 2 were neutropenic, hydrops is not a requirement for neutropenia – even mildly affected infants with HDFN can be neutropenic.

Neutropenia due to HDFN can persist for a year in some cases, but is not a life-long condition for babies with HDFN. Many neutropenic infants do not require treatment for neutropenia and are simply monitored via blood draws. In some cases neutropenia is treated with recombinant human granulocyte colony-stimulating factor may be administered to boost the neutrophil count 4.

Infants with neturopenia are at a higher risk for infection and may become sick more easily. Parents should be made aware of the risks of neutropenia and encouraged to take extra precautions to reduce infection (reduced visitors, increased hand washing, discouraging strangers from touching your baby when out in public). If a neutropenic infant does become sick, he or she should be taken to the doctor as soon as possible – it is common for neutropenic infants to need antibiotics and additional medications to get over an illness.

For additional articles about neutropenia, see our additional reading by topic page.

In addition to neutropenia due to HDFN and red blood cell antibodies, there is also a similar condition called neonatal alloimmune neutropenia (NAIN). In this disease, the mother makes antibodies against antigens on her baby’s neutrophils (instead of red blood cells). Just like with HDFN, neutrophil antibodies can cross the placenta and destroy fetal neutrophils. This leaves the fetus or newborn at risk for severe infections. We do not know of a website specific to NAIN, so if you have one, or a NAIN support group, please contact us and we will be happy to reach out. For more information about the various kinds of neutropenia and neutropenia in general, please contact the National Neutropenia Network. The National Neutropenia Network has created this leaflet to help people learn about neutropenia.

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