California Newborn Screening Program
WHEN TO COLLECT SPECIMENS
Timing the Collection (Section 6505)
The age at collection does not impact the testing for galactosemia and hemoglobin pattern. However, early collection can affect the results for other metabolic and hypothyroidism screening. It can result in a false positive for primary congenital hypothyroidism due to the biological phenomenon known as "neonatal surge." More significantly, early collection could result in a false negative for PKU and other amino acid disorders.
An ongoing study in California of siblings of PKU patients involving cord blood and serial blood samples (taken at 3, 6, 12, 18, and 24 hours of age) has shown that most newborns with PKU demonstrate elevated phenylalanine by six hours of age. To reduce the likelihood of missing a case, California recommends that newborns be a minimum of 12 hours old at the time of collection. The newborn’s physician, when reviewing the screening results, should note the baby’s age at time of collection and quantitative phe level. Newborns whose specimen was collected prior to 12 hours of age must have a second specimen submitted.
The State of California historically used a quantitative automated fluorometric method for PKU screening and now uses tandem mass spectrometry for screening of amino acids disorders. This differs from states that use the semi-quantitative Guthrie method, a microbiological inhibition assay. The nationally recommended guideline that a newborn be 24 hours of age before testing is applicable to those states using the Guthrie assay.
Obtain a specimen from a newborn using the following requirements and guidelines:
- Collect the specimen as close to time of discharge as is practical, but no earlier than two hours prior to discharge, when discharge occurs before six days of age.
- Collect the specimen on the sixth day if the newborn remains hospitalized beyond five days of age.
- The newborn should be at least 12 hours old since a neonate's metabolic system is still stabilizing before 12 hours of age.
For newborns transferred to another facility before six days of age:
- The receiving hospital is to obtain a specimen following above guidelines.
- The hospital of birth must complete and send to the Genetic Disease Branch the form "Hospital Report of Newborn Specimen Not Obtained (NBS-NO)" if the baby is transferred without collecting a specimen.
For newborns not born in a licensed perinatal health facility:
- If admitted to a licensed health facility within six days of age, follow the above guidelines unless there is evidence a specimen was already obtained.
- If admitted after six days but within thirty days of age, obtain specimen within 48 hours unless there is evidence it has already been obtained.
- If not admitted to a licensed health facility, it becomes the responsibility of the birth attendant or the newborn's physician to obtain a specimen between the second and sixth day of life.
- The birth registrar provides the person registering the birth with the pamphlet "Important Information for Parents of Babies WHo Have Not Yet Had the Newborn Screening Test" and information about how to have the baby tested. The registrar also completes the NBS-OH form, "Notification of Registration of Birth Which Occurred Out of a Licensed Health Facility," and sends it to GDB.
If a transfusion is anticipated:
- Collect the specimen prior to the transfusion of red blood cells, even if the newborn is under 12 hours of age. Infants who are transfused with red blood cells (RBC) must have a specimen collected prior to the transfusion. [Transfusions with plasma, platelets, or albumin will not significantly affect the screening.] In post-RBC-transfusion specimens, the donor's hemoglobin type can mask the newborn's. The donor blood can also supply the enzyme that the galactosemia screening measures, so that the specimen collected from a transfused newborn with low enzyme levels could appear normal. Futhermore, the signs and symptoms of galactosemia may be masked in the newborn who is receiving only a non-milk-based (lactose-free) formula, e.g., soy, Nutramigen®.
- If the neonate is less than 12 hours old at the time the pre-transfusion specimen is collected, a second specimen should be collected between 24 hours after the last transfusion and six days of age.
- Neonates who received intrauterine transfusion(s) should have both a newborn screen and Hb DNA testing on a whole blood specimen sent to the Hemoglobin Reference Laboratory. Contact the Area Service Center coordinator for collection and mailing information. The newborn's physician will need to monitor the child for signs of galactosemia.
- If no adequate specimen was obtained prior to transfusion, collect one sometime between 24 hours post-transfusion and the sixth day of life for immediate PKU and hypothyroidism results. Contact the Area Service Center coordinator for instructions on collection of a liquid blood specimen for hemoglobin DNA testing to be done at the hemoglobin reference laboratory as soon as the baby is stable. The baby's physician will need to monitor the child for signs of galactosemia.
- Alternatively, the cord blood specimen, if available, could be submitted as the pre-transfusion specimen for galactosemia and hemoglobin pattern. A heelstick specimen, which should be collected at least 24 hours after the transfusion, will provide results for PKU and hypothyroidism screening. Together, these two specimens represent a complete screen without needing to wait for three months.
The cord blood must be nonhemolyzed and free of clots, and is spotted on an NBS I-form. The test request form should indicate "cord blood." The specimen collection time is the same as the time of birth. This situation, i.e., providing a pre-transfusion specimen, is the only circumstance in which the use of cord blood is acceptable.
The timing of specimen collection should never be determined by staff convenience. Collecting NBS specimens at a routine time of day or upon admission to the NICU, regardless of the infant's age or the probability of an immediate transfusion, is not sound medical practice and is not in compliance with the State regulations. Any hospital that deviates from the State Regulations exposes itself to liability in the event of a missed case. In 1995, the Department of Health Services received a report of the first missed case of PKU in California since the expanded program began in 1980. The NBS specimen was collected at two hours of age upon admission to an NICU. The results were negative, well within the normal range. The baby had an extended stay and was never transfused. Therefore, there was no justification for not testing the baby on the sixth day. According to State Regulations, this baby should have been tested at six days of age. Subsequently, there have been two additional missed cases of PKU, both of which were tested at less than 12 hours of age.
Hospital well-baby nursery and NICU protocols must, at a minimum, reflect current NBS Program regulations. It is strongly recommended that they also reflect the Program guidelines. For assistance in developing or modifying procedures to meet State regulations and recommendations, contact the Area Service Center Newborn Screening Coordinator in your area.