Newborn screening – Put Prevention Into Practice, part 3 – excerpt from Clinician’s Handbook of Preventive Services by U.S. Public Health Service
Newborn screening for congenital hypothyroidism and phenylketonuria (PKU) is required in virtually all states. Testing for galactosemia and hemoglobinopathies is required in a majority of the states. Other conditions for which some states require newborn screening are maple syrup urine disease, homocystinuria, biotinidase deficiency, tyrosinemia, congenital adrenal hyperplasia, cystic fibrosis and toxoplasmosis. Screening for some conditions is voluntary in some states. Table 1 lists newborn screening policies of individual states.
Most children with congenital hypothyroidism who are not identified and treated promptly have irreversible mental retardation and varying degrees of growth failure, deafness and neurologic abnormalities comprising the syndrome of cretinism. The incidence is one per 3,600 to one per 5,000 live births. Infants who receive adequate treatment with thyroxine within the first weeks of life have normal or near-normal intellectual performance when tested at four to seven years of age.
This autosomal recessive aminoacidopathy leads to severe, irreversible mental retardation (IQ below 50) when untreated during infancy. The incidence is one per 10,000 to one per 25,000 live births. With early screening, diagnosis and optimal treatment with dietary restriction of phenylalanine, most children are in the normal range of intelligence.
This disease causes failure to thrive, vomiting, liver disease, cataracts and irreversible mental retardation. Death often results from Escherichia coli septicemia. The incidence is one per 60,000 to one per 80,000 live births. Removal from the diet of galactose-containing foods, especially milk, leads to a dramatic improvement in the patient, and all clinical features except mental retardation may improve or disappear.
Sickle cell disease and other hemoglobinopathies, such as thalassemia and hemoglobin E, are most common in persons of African, Mediterranean, Asian, Caribbean, and South and Central American ancestry. Affected persons may have overwhelming sepsis, chronic hemolytic anemia, episodic vascular occlusive crises, hyposplenism, periodic splenic sequestration and bone marrow aplasia. Carriers (genetic heterozygotes) do not suffer significant morbidity. In newborns with sickle cell disease, early detection allows prevention of septicemia with prophylactic penicillin and prompt clinical intervention for infection and sequestration crises.
Recommendations of Major Authorities
* The American Academy of Pediatrics recommends newborn screening according to each state’s regulations.
National authorities have made recommendations for the following specific conditions:
* The American Academy of Family Physicians, the American Thyroid Association, the Canadian Task Force on the Periodic Health Examination and the U.S. Preventive Services Task Force recommend that all neonates be screened for congenital hypothyroidism prior to discharge from the hospital nursery but no later than six days of age. Infants at risk for not being screened include those who are born at home, infants who are ill at birth, or infants who are transferred between hospitals early in life.
* The American Academy of Family Physicians and the U.S. Preventive Services Task Force recommend that all infants be screened for PKU at the time of nursery discharge or transfer regardless of age, but no later than seven days of age. Infants screened earlier than 24 hours after birth should be screened again before the third week of life.
* The Canadian Task Force on the Periodic Health Examination has made a similar recommendation, stating that since screening of newborns under four days of age may result in under-referral, a second test is justifiable.
* The Sickle Cell Disease Guideline Panel of the Agency for Health Care Policy and Research, U.S. Public Health Service recommends universal screening for sickle cell disease in all newborns. This recommendation has been endorsed by the American Academy of Pediatrics, the American Nurses Association and the National Medical Association.
The American Academy of Family Physicians the Canadian Task Force on the Periodic Health Examination and the U.S. Preventive Services Task Force all recommend screening for hemoglobinopathies in infants who are in high-risk ethnic groups.
Basics of Newborn Screening
1. A blood spot on filter paper should be obtained from every neonate before discharge or transfer from the nursery, regardless of the nature or status of the infant’s feeding or age.
2. For the full-term, well neonate, the specimen should be obtained as close as possible to the time of discharge from the nursery, and in no case later than seven days of age. If the initial specimen is obtained earlier than 24 hours after birth, a second specimen should be obtained at one or two weeks of age to decrease the probability that PKU and other disorders with metabolite accumulation will be missed as a consequence of testing on the first day of life.
3. Any premature infant, any infant receiving parenteral feeding or any neonate being treated for illness should have a specimen obtained for screening at or near the seventh day of life if a specimen has not been obtained before that time, regardless of feeding status. If an infant requires transfusion or dialysis prior to the routine time for obtaining the specimen and if the clinical status of the neonate permits, it is optimal to obtain the sample for screening prior to transfusion or dialysis. If a sample cannot be obtained beforehand, the clinician should ensure that an adequate specimen is obtained at a time when the plasma or red blood cells, or both, will again reflect the child’s own metabolic processes or phenotype.
Adapted from American Academy of Pediatrics, Committee on Genetics. Issues in newborn screening. Pediatrics. 1992;89:345-9. Reproduced with permission.
1. The same standards and techniques for the collection of blood specimens for neonatal screening programs should be applied for all of the congenital diseases. State screening agencies hold individual hospitals accountable for instituting policies that assure the correct collection of filter-paper blood samples.
2. The required information should be entered on the specimen collection kit with a ballpoint pen, not a soft-tip pen or a typewriter.
3. Universal precautions, including wearing gloves, should be taken for handling blood and disposing of used lancets in a biohazard container for sharp objects.
4. Site Selection: The source of blood must be the most lateral surface of the plantar aspect (walking surface) of the infant’s heel. Skin punctures to obtain blood specimens must not be performed on the central area of the newborn’s foot (area of the arch) or on the fingers of newborns. Puncturing the heel on the posterior curvature will permit blood to flow away from the puncture, making proper spotting difficult. A previous puncture site should not be lanced.
5. Site Preparation: Warming the puncture site can increase blood flow. A warm, moist towel at a temperature no higher than 42 [degrees] C (108 [degrees] F) should be placed on the site for three minutes. Also, holding the infant’s leg in a position lower than the heart will increase venous pressure.
6. Cleaning the Site: The infant’s heel should be cleaned with 70 percent isopropyl alcohol (rubbing alcohol). Excess alcohol should be wiped away with a dry sterile gauze or cotton ball and the heel allowed to air dry thoroughly. Failure to wipe off alcohol residue may dilute the specimen and adversely affect test results.
7. Puncture: To ensure that sufficient flow of blood is obtained, the plantar surface of the infant’s heel should be punctured with a sterile lancet to a depth of 2.0 to 2.4 mm or with an automated lancet device. The first drop of blood should be wiped away with sterile gauze. In small premature infants, the heel bone may be no more than 2.4 mm beneath the plantar heel skin surface and half this distance at the posterior curvature of the heel. Puncturing deeper may risk bone damage. The puncture site should not be milked or squeezed, as this may cause hemolysis and admixture of tissue fluids with the specimen.
8. Filter Paper Handling and Application: Care should be taken to avoid touching the area within the printed circle on the filter paper before collection. The filter paper should be touched gently against a large drop of blood and, in one step, a sufficient quantity of blood allowed to soak through to fill completely the circle on the filter paper. The paper must not be pressed against the puncture site on the heel. Blood should be applied to only one side of the filter paper. Both sides of the filter paper should be examined to assure that the blood has penetrated and saturated the paper. Successive drops of blood should not be layered within the circle. If blood flow diminishes so that the circle is incompletely filled, the sampling steps must be repeated at a different site. The blood sample should not be touched after collection, and water, feeding formulas, antiseptic solutions or any other contaminant should not be allowed to come into contact with the sample. The sample should be allowed to dry thoroughly before insertion into the envelope. Insufficient drying can adversely affect test results.
9. Hemostasis: After blood has been collected from the heel of the newborn, the foot should be elevated above the body and a sterile gauze pad or cotton ball pressed against the puncture site until the bleeding stops. It is not advisable to apply adhesive bandages over skin puncture sites in newborns.
Adapted from National Committee for Clinical Laboratory Standards. Blood Collection on Filter Paper for Neonatal Screening Programs – Second edition; Approved Standard. Villanova, Pa.: National Committee for Clinical Laboratory Standards; 1992. Permission to use portions of NCCLS document LA4-A2 has been granted by the National Committee for Clinical Laboratory Standards, copyright 1992.
Clinicians should ensure that children have received proper newborn screening and that test results have been received and evaluated. Clinicians should be aware of those patients at increased risk for not being screened. These include sick or premature neonates, neonates undergoing adoption or being transferred within or between hospitals, infants born at home, children of transient or homeless families, and infants born outside the United States and Canada. Newborn screening results should be documented in an easily accessible part of the patient record for future reference.
All abnormal results require confirmatory testing. With certain rare exceptions (e.g., galactosemia and maple syrup urine disease), treatment should not be instituted until a confirmatory test has been obtained. Prompt physical examination of patients with abnormal results is important. An patients with sickle cell disease should be started on penicillin prophylaxis as soon as the diagnosis is confirmed.
Appropriate counseling should be provided to all parents of children with abnormal results. This counseling should provide information about the significance of the results and need for retesting, implications for the child’s health, treatment regimens, symptoms to be alert for, and genetic issues for future childbearing.
Sickle Cell Disease: Guide for Parents. Agency for Health Care Policy and Research Publications Clearinghouse, PO Box 8547 Silver Spring MD 20907 (telephone: 800 358-9295).
Understanding PKU. PKU Clinic, Children’s Hospital Medical Center, 300 Longwood Ave., Boston, MA 02115 (telephone: 617-735-6650).
Most state health departments have their own pamphlets on newborn screenings for parents that can be ordered by clinicians.
Blood Collection on Filter Paper for Neonatal Screening Programs – Second Edition; Approved Standard. National Committee for Clinical Laboratory Standards (NCCLS), 771 E. Lancaster Ave., Villanova, PA 19085 (telephone: 215-525-2435). An educational videotape depicting the LA4-A2 collection procedure is also available from NCCLS.
Sickle Cell Disease: Clinical Practice Guideline; Sickle Cell Disease: Guideline Report; Sickle Cell Disease: Quick Reference Guide. Agency for Health Care Policy and Research Publications Clearinghouse, P.O. Box 8547, Silver Spring, MD 20907 (telephone: 800-358-9295).
The Clinician’s Handbook of Preventive Services, from which this article was excerpted, was designed to be used alone as a reference or a textbook. It is also, however, part of an integrated set of resources to improve the delivery of preventive services in clinical settings. These resources, which constitute the Put Prevention into Practice Education and Action Kit, include hand-held minirecords for patients and parents and a collection of office materials. The Put Prevention into Practice Education and Action Kit, including the Clinician’s Handbook, may be ordered by writing the Superintendent of Documents, P.O. Box 371954, Pittsburgh, PA 15250-7954, or by calling 202-783-3238 (FAX: 202-512-2250).
The AAFP Put Prevention into Family Practice materials may be purchased either in kit form or as individual items through the AAFP Order Fulfillment Department (telephone: 800-944-0000). Request product #1999 to obtain the Put Prevention into Family Practice kit. The kit provides a listing of replacement materials to order individually.
American Academy of Family Physicians, Commission on Public Health and Scientific Affairs. Age charts for periodic health examination. Kansas City, Mo.: American Academy of Family Physicians, 1993.
American Academy of Pediatrics, Committee on Genetics: Issues in newborn screening. Pediatrics 1992;89:3 45-9.
American Academy of Pediatrics, Committee on Genetics: Newborn screening fact sheets. Pediatrics 1989;83:449-64.
The periodic health examination. Canadian Task Force on the Periodic Health Examination. Can Med Assoc J 1979;121:1193-254.
Council of regional networks for genetic services: 1989 newborn screening report final report December 1990. New York: Council on Regional Networks for Genetic Screening, 1993.
Donnell G, ed. Galactosemia: new frontiers in research. Bethesda, Md.: National Institutes of Health, National institute of Child Health and Development, 1992.
Newborn screening: an overview of newborn screening programs in the United States and Canada. Springfield, Ill.: Illinois Department of Public Health, 1990.
Hannon WE, ed. Blood collection on filter paper for neonatal screening programs. 2d ed. Villanova, Pa.: National Committee for Clinical Laboratory Standards, 1992.
Newborn screening for sickle cell disease and other hemoglobinopathies. Bethesda, Md.: US Dept of Health and Human Services, Public Health Service, National Institutes of Health, Office of Medical Applications of Research, 1987.
Sickle Cell Disease Guideline Panel. Sickle cell disease: screening, diagnosis, management, and counseling in newborns and infants. Rockville, Md.: US Dept of Health and Human Services, 1993; DHHS publication no. AHCPR 93-0562.
U.S. Preventive Services Task Force. Screening for phenylketonuria. In: Guide to clinical preventive services. Baltimore, Md.: Williams & WAW, 1989:diap 19.
U.S. Preventive Services Task Force. Screening for thyroid disease. In: Guide to clinical preventive services. Baltimore, Md.: Williams & Wilkins, 1989:chap 17.
COPYRIGHT 1994 American Academy of Family Physicians
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