Newborn Testing

You made it! On this page, you will find many of the things that you will need to know about after you’ve delivered a baby with HDFN. There is so much to be done after you have a baby, and a lot to educate yourself about. Unfortunately many mothers find a huge disconnect between their rigorous prenatal care and the care that baby receives after discharge. Often it falls on the parents to ensure that their children receive the appropriate tests, monitoring and treatment at the correct times. You are your baby’s best advocate. Understanding your child’s disease is so important to keeping him or her safe. With proper testing/monitoring, and a skilled medical team, you have every chance at a healthy baby once the antibodies clear his/her system. Write down any questions that you have for your care team in your notebook. Remember to discuss all tests and their results with your health care team. To make tracking your baby’s results easier, you can download and print a copy of our personal care record. There’s even a copy of all the referenced normal laboratory values. 

Titers do not determine how baby will do after birth. Even moms with low titers, such as 1:2, can have babies at risk for brain damage from high bilirubin. Always get baby tested after birth, regardless of titer levels. 


Direct Antiglobulin Test

The blood test for baby that determines if the antibodies are attached to his blood cells.

What is it?
Also called the Direct Coombs Test. The direct antiglobulin test (DAT) is performed to determine whether an anemic patient with evidence of hemolysis has hemolytic disease of the fetus and newborn. If baby has a positive DAT there are antibodies already bound to and attacking the red blood cells. These antibodies can be removed from the RBC and each specific antibody can be identified. While the IAT test shows if Mom is making antibodies and has them floating around loose in her blood, the DAT shows if the antibodies are present in the baby’s blood and bound to the red blood cells 22.

When is it done?
This test should be run at birth. It may be repeated if the baby shows signs of HDFN later on.

Why is it done?
This test is done to see if there are any of mom’s antibodies bound to and attacking the baby’s blood.

How is it done?
This test can be done by taking blood from the umbilical cord or through a heel stick.

What do the results mean?
A negative DAT means that there are not antibodies bound to the baby’s blood. A positive DAT means that there are antibodies attacking the baby’s blood. A positive result will mean that your baby needs additional testing and monitoring.

Additional Information
Occasionally, especially with IUTs, the baby may have a negative DAT and still be severely, even fatally affected by HDFN. In this case, an IAT may be run to see if there are antibodies in the blood that aren’t bound and attacking the cells or an antigen phenotype may be run to determine if the baby has inherited the offending antigen. Some antibodies are more prone to having negative DAT and a severely affected baby (though this can happen with any antibody) – medical literature has documented this with anti-C, anti-c, anti-E, anti-Fya, anti-Good, anti-H, anti-Jra, anti-M, and anti-Mta.


Total Serum Bilirubin (TSB)

The blood test that determines if the baby’s bilirubin is building up.

The bilirubin test is how they will monitor baby’s bilirubin (bili). Bilirubin is released when blood cells are destroyed, so as our antibodies destroy the baby’s blood cells, high bilirubin levels can build up. High levels of bilirubin can be dangerous – poorly treated bilirubin can cause brain damage and even death. Jaundice can rob your baby of a normal life.

When is it done?
Bilirubin should be tested at birth, and frequently thereafter. Often it is tested every 6, 12, or 24 hours while in the hospital. Bilirubin due to HDFN tends to peak on days 4-6, but can require treatment for up to 3 weeks.

How is it done?
This test can be done by taking blood from the umbilical cord or through a heel stick. Occasionally a device called a bilichek can be used to check the bilirubin by scanning the infant’s forehead – this device should not be used after the baby has had phototherapy. Some doctors do not believe the bilichek is accurate enough for babies with HDFN and prefer the blood draws. Others will use a mixture of both, alternating heel sticks with the bilichek.

How often is it done?
Bilirubin should be checked immediately after birth and as frequently as every 4-6 hours afterwards. If the levels aren’t too high, your doctor may do every 12 hours until discharge, and then daily for the first week or two. Bilirubin tends to peak around day 4 or 5 with HDFN babies. One thing to watch out for, is rebounding jaundice. Babies with HDFN tend to have a decrease in bilirubin when on lights, but rapidly increase when the lights are removed. This can occur up to 3-4 days after removal from lights, so keep checking the bilirubin levels even after treatment has ended. Bilirubin levels will still be checked periodically by the doctor for the first month or so of baby’s life (weekly or biweekly after treatment ends).

What do the results mean?
Below is the common bilirubin graph. First determine your baby’s age in hours, then plot your results. The merged graph looks different, but the values are still the same. We have simply removed the low risk line (infants with HDFN will never be considered low risk), and combined the phototherapy graph and the exchange transfusion graph onto one image.

You can also use the tools at http://peditools.org/bili/index.php to plug in your baby’s information.

Bilirubin comes as 3 parts: total serum bilirubin, indirect bilirubin (sometimes called unconjugated), and direct bilirubin (conjugated). Healthy term infants may tolerate serum bilirubin levels of 25 mg/dl. Infants are more prone to the toxic effects of bilirubin if they have any of the following: acidosis, prematurity, septicemia, hypoxia, hypoglycemia, asphyxia, hypothermia, hypoproteinemia, exposure to drugs that displace bilirubin from albumin, or hemolysis (HDFN).

TOTAL bilirubin should be used when judging baby. DO NOT subtract the direct (conjugated) from the total 49. This is an old practice and is not recommended by the American Academy of Pediatrics.

Phototherapy should be started anytime there’s a positive DAT and the cord blood is more than 3.5 mg/dL 5.  Some doctors use a cord bilirubin of 4 mg/dL as criteria for an exchange transfusion.

If numbers are high
Bilirubin can be very dangerous. If your baby is approaching the exchange threshold, the American Academy of Pediatrics recommends IVIG and exchange transfusion. It is very important to receive prompt treatment for bilirubin to prevent brain damage. Don’t delay on bilirubin treatment because it can cause irreparable brain damage and Kernicterus. Another complication from bilirubin is Bronze Baby Syndrome.

The following are indications for exchange transfusion 5:

  • Severe anemia (Hb < 10 g/dL)
  • Cord bilirubin > 4 mg/dL.
  • Rate of bilirubin rises more than 0.5 mg/dL despite intensive phototherapy
  • Severe hyperbilirubinemia
  • Serum bilirubin-to-albumin ratio exceeding levels that are considered safe

IVIG has been shown to reduce the need for an exchange transfusion.

If levels are high, phototherapy and supportive treatment should begin immediately because jaundice severe enough to lead to kernicterus (permanent brain damage), may develop. The goal of therapy is to prevent the concentration of indirect bilirubin from reaching neurotoxic levels.

If numbers are low
Great! You’re probably good to go but the bilirubin levels will still be checked periodically by the doctor for the first few weeks of baby’s life.


Hemoglobin

The blood test that determines if baby is anemic.

What is it?
Hemoglobin is a protein in red blood cells that carries oxygen. A blood test can tell how much hemoglobin you have in your blood 23. It is usually abbreviated Hb or Hgb and is measured in grams per deciliter. The hemoglobin test determines if the baby is anemic. It is often done as part of a complete blood count (CBC).

When is it done?
Hemoglobin should be tested at birth, and frequently thereafter.

How is it done?
This test can be done by taking blood from the umbilical cord or through a heel stick.

How often is it done?
How often hemoglobin is checked depends on each case. Usually it is checked every 1-3 days in the hospital, or if baby is showing symptoms of being anemic. If baby’s Hgb is dropping, more frequent checks will be needed. As baby gets older, less frequent checks are usually needed. Because babies with HDFN are at risk for developing late onset anemia, hemoglobin levels should be checked until at the baby is at least 12 weeks old.

What do the results mean?
The calculated minimum acceptable hemoglobin concentration is 6 g/dl for children and adults, 12 g/dl for preterm infants and 11 g/dl for full-term neonates at birth. The minimum hemoglobin concentration should be 2 g/dl higher in patients who require increased oxygen or suffer from other serious disorders. Because of how the baby deals with oxygen, the minimum value of 12 g/dl or 11g/dl decreases by approximately 1 g/dl each week for 5 or 6 weeks until the minimum of 6g/dl for children and adults is reached 25.

If numbers are high
If the hemoglobin is above 10 g/dL (in the absence of specific risk factors related to the patient’s clinical characteristics) there is no need to transfuse red blood cells. Hemoglobin should still be checked regularly.

If numbers are low
Depending on how low the numbers are, treatment may be non urgent or urgent. If non-urgent, the baby will be monitored to see if he will start to make his own blood cells and recover from anemia on his own. If treatment is urgent, a blood transfusion will be performed.

Subjects with Hgb concentrations below 7 g/dL almost always require transfusion therapy. In stabilized patients with Hgb values between 8 and 10 g/dL, the decision whether to transfuse is based on an evaluation of clinical status; patients with values above 10 g/dL rarely require transfusion.

Additional Information
You should be wary of giving your baby iron supplements. Most babies with HDFN have normal or high iron levels and serious damage or death can occur if they are given iron supplements. Unless the baby’s ferritin level is specifically tested, DO NOT GIVE IRON. 

Hematocrit

Another blood test that can determine if a baby is anemic.

Hematocrit is a blood test that measures the percentage of the volume of whole blood that is made up of red blood cells28. It is abbreviated HCT or Htc, and may be done as part of a complete blood count (CBC). Hematocrit will determine if the baby is anemic or not.

When is it done?
If testing for anemia is done via hemoglobin, hematocrit may not be run. If anemia is checked via hematocrit, it should be tested at birth, and frequently thereafter.

How is it done?
This test can be done by taking blood from the umbilical cord or through a heel stick.

How often is it done?
How often hematocrit is checked depends on each case. Usually it is checked every 1-2 days in the hospital, or if baby is showing symptoms of being anemic. If baby’s hematocrit is dropping, more frequent checks will be needed. As baby gets older, less frequent checks are usually needed. Because babies with HDFN are at risk for developing late onset anemia, hematocrit levels should be checked until at the baby is at least 12 weeks old.

If numbers are high
Great, a transfusion may not be needed, but the hematocrit levels should still be checked regularly until at least 12 weeks of age. It should also be remembered that patients with acute hemorrhage can have normal, or even high, Htc values until the plasma volume is restored; the clinical evaluation of the patient in this situation is, therefore, extremely important 26

If numbers are low
Depending on how low the numbers are, treatment may be non-urgent or urgent. If non-urgent, the baby will be monitored to see if he will start to make his own blood cells and recover from anemia on his own. If treatment is urgent, a blood transfusion will be performed.

After transfusion, the hematocrit goal will be >25% for anemia with symptoms, and >20% for anemia without symptoms.


Ferritin Test

The essential safeguard against iron overload

Ferritin is a protein in that carries iron. Most of the body’s iron is bound to ferritin. A blood test can tell how much ferritin you have in your blood. A high ferritin level means baby may be in danger of an iron overdose. Most babies with HDFN have a normal or high ferritin level depending on if they had IUTs. IUTs are done with adult blood cells that are very rich in ferritin. It is very important even if baby has not had a transfusion that you not give iron supplements or vitamins with iron in them until you have the ferritin level tested.

When is it done?
Ferritin is tested at request. It is not part of a normal blood draw unless the provider is recommending iron supplements.

Why is it done?
Ferritin is checked to find out the baby’s iron levels and to rule out iron deficiency anemia.

How often is it done?
How often ferritin is checked depends on each case. Most of the time the doctor will only draw it once unless the levels are really high.

What do the results mean?
If numbers are high
High ferritin levels (over 1,000 ng/mL) can mean a large buildup of iron in the body. With HDFN babies, this is usually called acquired hemochromatosis, and can be caused by multiple transfusions. Too much iron in the body’s organs can affect how the organ works.

If numbers are low
Low ferritin levels generally mean that anemia is iron deficiency anemia and can be helped with iron supplements.

Additional Information
You should be wary of giving your baby with HDFN iron supplements. Most HDFN babies have normal or high iron levels and serious damage or death can occur if they are given iron supplements. Unless the Ferrin level is specifically tested, medical literature recommends to avoid them. It is especially important to avoid them until the transfusion window has closed. You will also want to check on the amount of iron in formula if you formula feed. Try to choose a no or low iron formula.


Reticulocyte Count (Retic)

The test that tells how quickly baby is making new blood cells.

A reticulocyte count (retic) is a blood test that measures how fast specific red blood cells (RBCs), called reticulocytes, are being made by the bone marrow and released into the blood 30.

When is it done?
Retic should be tested at birth, and frequently thereafter.

Why is it done?
This test is done to see how well the bone marrow is working at making red blood cells and to check to see if treatment for anemia is working. For example, a higher reticulocyte count means that treatment to reverse the anemia is working 30.

How often is it done?
How often retic is checked depends on each case. Usually it is checked every 1-2 days in the hospital, or if baby is showing symptoms of being anemic. If baby’s retic is dropping, or not increasing properly, more frequent checks may be needed. As baby gets older, less frequent checks are usually needed.

What do the results mean?
The retic is given as the percentage of RBCs that are reticulocytes. The normal range can vary from lab to lab, but this is a general guide. Newborns have a normal reticulocyte count of 2.5% to 6.5%. In normal babies, this value drops within 2 weeks to 0.5% to 2.0%. (30) In babies with HDFN, it is normal for the retic to remain higher for longer as the baby combats anemia.

If numbers are high
A high retic means more red blood cells are being made by the bone marrow.

If numbers are low
A low retic means that fewer RBCs are being made. Retic can be low after baby has had an IUT. It is actually beneficial for babies to have a retic of 0 at certain times. This is when you have replaced the baby’s blood with donor blood, and do not want the baby making any more of his own blood cells until after he is delivered and can have an exchange transfusion to get rid of the antibodies. If there are none of the baby’s blood cells, then there is nothing for the mother’s antibodies to attack. It can take a while for babies to begin to make their own red blood cells after delivery, so the retic will be checked closely for several weeks.

Norma reticulocyte values

Neutrophil Count

45% of babies with HDFN have low neutrophils.

Neutropenia is common in babies with HDFN and can last for a year. Up to half of all babies with HDFN develop isoimmune neonatal neutropenia (INN) 38. This test checks to make sure that baby is not neutropenic. The neutrophil count is how they will monitor baby’s neutrophils and decide how to treat the baby.

When is it done?
The neutrophil count should be tested at birth, and every 1-2 weeks depending on numbers.

How is it done?
Neutrophil counts are done from a blood sample. Frequently they are part of a CBC, but check with your doctor or lab to make sure.

How often is it done?
It is done every 1-2 weeks depending on numbers. If checking baby for late onset anemia, it would be easy to check the neutrophil count at the same time. Low neutrophil count can persist for up to 28 weeks.

What do the results mean?

Below are is the table for the range of neutrophils in term and preterm infants 41

Normal neutrophil levels

If numbers are high
Your baby is not neutropenic.

If numbers are low
Neutropenia is defined as an absolute neutrophil count (ANC) of less than 1.5 (x109/L)


Thrombocyte (Platelet) Count

25% of babies with HDFN have a low thrombocyte count.

Babies with HDFN are at risk for low platelets (isoimmune thrombocytopenia) 48. This risk is higher if the baby has had IUTs. The platelet count  is how they will monitor platelets and decide how to treat the baby.

When is it done?
The platelet count should be tested at birth, and every 1-2 weeks depending on numbers.

Why is it done?
Babies with HDFN are at risk of developing isoimmune thrombocytopenia. This risk is higher if baby had to have IUTs.

How is it done?
Platelet counts are done from a blood sample. Frequently they are part of a CBC, but check with your doctor or lab to make sure.

How often is it done?
It is done every 1-2 weeks depending on numbers. If checking baby for late onset anemia, it would be easy to check the platelet count at the same time.

What do the results mean?
Thrombocytopenia is defined as a platelet count of less than 150 x 109/L. This value is the same regardless of age 45.

If numbers are high
Your baby is not thrombocytopenic.

If numbers are low
Thrombocytopenia is defined as a platelet count of less than 150 x109/L.

Normal Thrombocyte Values

Remember…

  • Titers do not determine how baby will do after birth. Even moms with low titers, such as 1:2, can have babies at risk for brain damage from high bilirubin. Always get baby tested after birth, regardless of titer levels. 
  • Parents must take the initiative to ensure that all of the appropriate tests are run for infants with HDFN.
  • If your baby has had IUTs, the state required newborn blood screening may be off (it may be testing donor blood and not baby’s blood), and should be repeated at 1 year of age.
  • You are your baby’s biggest advocate. If you do not feel like your needs are being met, seek a second opinion.
  • You can have a perfectly healthy baby when this is over. 
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