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[Routine screening for inborn errors using urine filterpaper specimens at age 4-5 weeks (author's transl)]
Insights
Urine screening detects inborn errors of amino acid metabolism missed by newborn blood tests, identifying conditions like Cystinuria and Histidinaemia. However, the rarity of exclusively urine-detectable disorders necessitates re-evaluating its overall usefulness.
Area of Science:
- Biochemistry
- Genetics
- Pediatrics
Context:
- Newborn blood screening effectively detects many metabolic disorders.
- Certain inborn errors of amino acid metabolism are not reliably detected by newborn blood screening.
- Urine screening offers a complementary diagnostic approach.
Purpose:
- To evaluate the effectiveness of urine screening for detecting inborn errors of amino acid metabolism in newborns.
- To compare the diagnostic yield of urine screening with newborn blood screening.
- To assess the overall utility of urine screening in pediatric metabolic disorder detection.
Summary:
- A 4-6 week urine screening program using thin-layer chromatography tested 70,400 newborns.
- The study identified various metabolic disorders including incomplete Cystinuria, Prolinuria, and Histidinaemia.
- Urine screening detected cases of Histidinaemia missed by newborn blood screening due to low initial blood levels.
Impact:
- Highlights the limitations of newborn blood screening for specific metabolic disorders.
- Identifies rare but treatable conditions missed by standard newborn screening protocols.
- Suggests a need to re-evaluate the role and cost-effectiveness of urine screening programs.
Abstract:
Since 1972 we have been using a urine screening for the detection of inborn errors of amino acid metabolism, which cannot be revealed in newborn-blood-screening with Guthrie's bacterial inhibition assay. It is performed at an age of 4-6 weeks by means of thin layer chromatography of urine specimens collected on filter paper using a method adapted by us for mass-screening. We tested 70,400 newborns and found 59 cases of incomplete Cystinuria, 9 of Prolinuria, 3 of Histidinaemia and one each of Hartnup disease, Alkaptonuria, Glycinuria and Hydroxyprolinuria. The problems of the disorders found are discussed. Comparison with newborn-blood-screening that 3 cases of Histidinaemia, proven by enzyme assay were missed by newborn-blood-screening because of their (still low) low blood levels. On the other hand we did not find additional cases of phenylalanine-metabolic disorders. These cases were probably all already detected by newborn-blood-screening. Homocystinuria, Maple syrup urine disease and Arginino-succinicaciduria which are rare diseases were neither found in the urine or blood tests. As disorders, detectable by means of urine screening exclusively and curable, are rare urine screening has to be reevaluated for its usefulness.