Blood Disorders That the Newborn Screen Detects

Today in the U.S., all newborns undergo testing called the newborn screen. This test is usually collected before the infant is discharged from the hospital. The blood is collected on filter paper called a Guthrie card and sent to the state lab.

In some states, the test is repeated about two weeks later. The first disorder screened was phenylketonuria (PKU); some people still refer to this as the PKU test, but today numerous disorders are screened with this small blood sample. The purpose of the newborn screen is to identify inherited conditions, so that treatment may start early and prevent complications.

There are several blood disorders that can be identified on the newborn screen. The testing is not exactly the same in all 50 states, but in general, most of these will be detected.


Sickle Cell Disease

Nurse handing newborn baby to mother

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The first blood disorder added to the newborn screen was sickle cell disease. Initially, testing was restricted to certain races or ethnic groups, but with increasing population diversity, now all infants are tested. The newborn screen can detect both sickle cell disease and sickle cell trait. Children identified with sickle cell disease are started on penicillin to prevent life-threatening infections. This simple measure markedly reduced the mortality rate from sickle cell disease.


Beta Thalassemia

The goal of screening for beta thalassemia is to identify children with a beta thalassemia major who will require a monthly blood transfusion for survival. It is difficult to determine if a child will need lifelong transfusions based on the newborn screen alone, but children identified as having beta thalassemia will be referred to a hematologist so they can be monitored closely for severe anemia.


Hemoglobin H

Hemoglobin H is a type of alpha thalassemia that results in moderate to severe anemia. Although these patients rarely need monthly blood transfusions, they may have severe anemia during illnesses with fever requiring transfusions. Identifying these patients early allows parents to be educated on the signs and symptoms of severe anemia.


Hemoglobin C

Similar to hemoglobin S (or sickle hemoglobin), hemoglobin C results in a red blood cell that may also appear like a sickle cell, rather than the classic doughnut shape. If one parent has the sickle cell trait and the other one has hemoglobin C trait, they have a 1 in 4 chance of having a child with Hemoglobin SC, a form of sickle cell disease. 

Other hemoglobin C diseases such as hemoglobin CC disease and hemoglobin C/beta thalassemia. These are not sickling disorders. These result in a varying amount of anemia and hemolysis (red blood cell breakdown), but not pain like sickle cell.


Hemoglobin E

Prevalent in Southeast Asia, red blood cells with hemoglobin E have decreased production of the beta globin chain and therefore have difficulty maintaining their shape. Most important is combining hemoglobin E and beta thalassemia which can result in thalassemia major, and a need for lifelong transfusions. 

If an infant inherits hemoglobin E from each parent, they can have hemoglobin EE disease. Hemoglobin EE disease has little to no anemia with very small red blood cells (microcytosis).


Variant Hemoglobin

In addition to hemoglobins S, C, and E there are over 1000 variations of hemoglobin. These hemoglobins have unusual names like Constant Spring and Memphis (they are named after the location where they were first identified). The large majority of these are of no clinical significance. For the majority of affected infants, it is recommended to repeat blood work around 9 to 12 months to determine if this is of any significance.


Alpha Thalassemia Trait

Sometimes alpha thalassemia trait (or minor) can be identified on the newborn screen. Generally, the result will mention hemoglobin Barts or fast bands. Alpha thalassemia trait can cause mild anemia and small red blood cells but usually goes undetected. 

However, just because a baby has a normal newborn screen does not mean that they do not have alpha thalassemia trait; it can be difficult to detect. Later in life alpha thalassemia trait may be confused with iron deficiency anemia.

Know Your Child's Results

Make sure you review the results of your child's newborn screen with your pediatrician. Your child may not have one of these disorders but may be a carrier for one. This is important information to share with your child before they start their own family.

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