Health care professionals and parents often ask the following questions about newborn screening:
What disorders are tested in newborn screening?
Who must be tested?
How is the specimen to be taken?
When should the specimen be taken?
What about feedings?
What about TPN (hyperalimentation)?
Why should every baby be tested?
What if there is a family history of a disorder (as in a previous child)?
What if an infant develops symptoms of a disorder in the first weeks of life?
When should repeats be collected?
Does a screen negative result mean the infant is not at risk for that condition?
Where can I obtain additional information specific to each condition in the screening profile?
How can I contact my state’s screening program?
What disorders are tested in newborn screening?
Currently, all state programs have screening tests for PKU and congenital hypothyroidism. More than 40 programs screen for sickle cell disease and 48 screen for galactosemia (1). To find the disorders currently screened in your state, go to the National Newborn Screening & Genetics Resource Center.
Who must be tested?
Every baby born in the United States should be tested for the panel of disorders specified by their state.
How is the specimen to be taken?
A blood specimen must be taken from the infant’s heel and applied to the circles on the special paper of the form. Contact your state’s newborn screening program for more information.
When should the specimen be taken?
Timeline for Specimen Collection
| Day of Life |
1st |
2nd |
3rd |
4th |
5th |
| Age in Hours |
Birth |
24 |
48 |
72 |
96 |
| Spec. Quality |
(A) Limited |
(B) Satisfactory |
(C) Optimal |
Period A: Birth to 24 hours of age (first day of life or day of birth). Though a repeat specimen will be necessary, a specimen should be taken in the following instances:
- The infant will be discharged from the hospital or institution prior to 24 hours of age.
- A blood transfusion is to be administered.
These specimens are valid for testing galactose-1-phosphate uridyl transferase (galactosemia), sickle hemoglobin (sickle cell disease), octanoylcarnitine (MCADD), and biotinidase (biotinidase deficiency). A repeat (second) collection should be taken between 48 and 120 hours of age.
Period B: 24 to 48 hours of age (second day of life). This interval is a satisfactory collection time. Statistical estimates indicate there may be a slightly increased risk of erroneous results in specimens taken during this interval, but after extensive review, the American Academy of Pediatrics concluded that the collection of a routine repeat blood specimen was not productive if the initial screening was performed within this interval.
Period C: 48 to 120 hours of age (third to fifth day of life). This interval is the optimum time for collection.
What about feedings?
Effects of feeding practices on the accuracy of screening in the first three days of life remain uncertain. However, it is generally felt they are a minor factor relative to the infant’s age.
What about TPN (hyperalimentation)?
The specimens of infants receiving TPN may give erroneous and misleading results in tests for MCADD and the aminoacidopathies. Whenever possible, a newborn screening specimen should be taken before initiation of these procedures.
Why should every baby be tested?
The screening panel has been selected to identify those newborns at risk for disorders that may not be readily identified by physicians. The disorders are rare, initial symptoms are minimal or too generalized to lead to early diagnosis. Delayed identification could lead to irreversible damage or death. Since the genetic disorders are recessive, there may be no known family history prior to identification of a condition in an infant.
What if there is a family history of a disorder (as in a previous child)?
To expedite processing and in some cases provide confirmatory testing, the screening laboratory should be informed of a family history of one of the disorders in the panel. It is recommended that two specimens taken at least a few days apart be sent for analysis. If the family history involves galactosemia or maple syrup urine disease, the nearest Specialty Care Center should be notified prior to delivery to arrange immediate testing after birth, since these disorders, if not treated immediately, may have a rapid downhill course. A newborn screening specimen also should be submitted for complete panel analysis.
What if an infant develops symptoms of a disorder in the first weeks of life?
The screening program should be contacted by hospital staff or the physician to ascertain if the test results are available. Results will be reported, and tests repeated for assurance of accuracy. Often calls for results come in prior to receipt of a specimen. If this occurs, an additional specimen should be collected at the hospital and sent by an overnight courier for prompt testing.
When should repeats be collected?
- Invalid specimens: Repeat should be taken as soon as arrangements can be made, since this infant has not been screened.
- Screen positive: Unless instructed otherwise, a repeat should be taken within one week of notification.
Does a screen negative result mean the infant is not at risk for that condition?
No. Many factors can contribute to a negative result in the newborn screen. Some of these—late onset of the condition, transfusion, TPN, mislabeling of the specimen—can result in a false-negative for that child. No child displaying symptoms for one of the conditions in the screening panel should be judged not-at-risk for that condition. All possibilities, including a false-negative newborn screen, should be considered when evaluating a sick infant.
Where can I obtain additional information specific to each condition in the screening profile?
Contact your state’s newborn screening program for clinical specialists on each of these conditions.
How can I contact my state’s screening program?
Go to the Web site of the National Newborn Screening & Genetics Resource Center.
