Timing of Specimen Collection The American Academy of Pediatrics recommends that the specimen not be collected until the newborn is at least 24 hours old (1) (see graph below). This has become more difficult as hospital stays have shortened. A specimen taken prior to 24 hours can be used to screen for galactosemia, biotinidase deficiency, MCADD, cystic fibrosis and sickle hemoglobin, but will not reliably differentiate infants at risk for the other disorders (e.g., PKU) in the screening panel from those not at risk for the disorders. Analysis of screening results suggests that a specimen taken on the second day of life is usable for testing, with a slightly increased risk of not detecting an abnormal condition (2-6). Discharging an infant without collecting a specimen, with intent to collect it later, greatly increases the risk of missing an infant with one of the screened conditions (7).
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
Transfusion: The optimum collection time remains the period between the third and fifth day of life. If the infant is to receive a transfusion, every effort must be made to collect a specimen prior to transfusion, since even small transfusions may invalidate screening results. Infants receiving transfusions with no prior screening test need two collections: three days or more after the most recent transfusion and three months after the final transfusion.
Total Parenteral Nutrition (TPN): The optimum collection time remains the period between the third and fifth day of life. If the infant is to receive TPN, every effort must be made to collect a specimen prior to treatment, since even small amounts of TPN may invalidate screening results. Infants receiving TPN with no prior screening test need two collections: three days or more after the most recent TPN and three months after the final TPN.
Premature and Sick Infants: Very lengthy hospital stays require specimens to be collected according to state protocols, keeping in mind the considerations around transfusion and TPN.
Summary for Specimen Collection Timing
Infant Status
Time of Collection
Normal, Healthy
Day 1:If to be discharged from hospital or birthing center & repeated on day 3-5. Day 2: Acceptable Day 3-5: Optimum
Transfused
Prior to transfusion; or if no pretransfusion collection was taken, three days after most recent transfusion; with repeat three months after final transfusion.
TPN
Prior to initiation of TPN; or if no pre-TPN collection was taken, three days after most recent TPN; with repeat three months after final TPN.
Premature, Sick or Extended Stay
Prior to transfusion—any age & on day 3-5 or three days after most recent transfusion & at discharge or at one month of age, whichever comes first.
References 1. Committee on Genetics, American Academy of Pediatrics. Newborn screening fact sheets. Pediatrics 1996;98(3):473-501.
2. Hanley WB, Demshar H, Preston MA, Borczyk A, Schoonheyt WE, Clarke JT, Feigenbaum A. Newborn phenylketonuria (PKU) Guthrie (BIA) screening and early hospital discharge. Early Hum Dev 1997;47(1):87-96.
3. Doherty LB, Rohr FJ, Levy HL. Detection of phenylketonuria in the very early newborn blood specimen. Pediatrics 1991;87(2):240-4.
4. McCabe ERB, McCabe L, Mosher GA, Allen RJ, Berman JL. Newborn screening for phenylketonuria: predictive validity as a function of age. Pediatrics 1983;72(3):390-8.
5. Koch R, Twelmeyer D, Berlow S. (Letters to the editor). McCabe ERB, McCabe L (Reply) Re: Newborn screening for phenylketonuria: predictive validity as a function of age. Pediatrics 1984;73:737-40.
6. Office of Technology Assessment, Congress of the United States. Healthy children: investing in the future. Washington (DC); 1988.
7. Holtzman C, Slazyk WE, Cordero JF, Hannon WH. Descriptive epidemiology of missed cases of phenylketonuria and congenital hypothyroidism. Pediatrics 1986;78(4):553-8.
The information contained in this section does not constitute the endorsement of any specific state policy or procedure by the March of Dimes. Content is based on the New York State Department of Health manual “Newborn Screening in New York State: A Guide for Health Professionals,” provided by the Newborn Screening Program, Wadsworth Center, New York State Department of Health. The material has been modified for a national audience, and additional information has been added by the March of Dimes.
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