Which test is NOT routinely included in newborn screening for metabolic disorders?

Which test is NOT routinely included in newborn screening for metabolic disorders?

• A. Glycosylated hemoglobin
• B. Urine electrolytes
• C. Serum amino acids
• D. Serum AST, GGT, ALT

Answer: (A)

Newborn screening for metabolic disorders looks for abnormal metabolites in a blood sample so we can detect inborn errors of metabolism early and start treatment. Glycosylated hemoglobin measures average blood glucose over months and is used to monitor diabetes, not to identify metabolic disorders in newborns; plus HbA1c is not reliable in newborns because fetal hemoglobin is present. So it isn’t part of routine newborn metabolic screening. The test that fits the screening purpose is serum amino acids, which are specifically measured by the tandem mass spectrometry panel to detect amino acid and fatty acid metabolic conditions. Tests such as liver enzyme panels or urine electrolyte studies aren’t part of the standard newborn metabolic screen, though they may be used in broader evaluations when indicated.

Newborn screening for metabolic disorders looks for abnormal metabolites in a blood sample so we can detect inborn errors of metabolism early and start treatment. Glycosylated hemoglobin measures average blood glucose over months and is used to monitor diabetes, not to identify metabolic disorders in newborns; plus HbA1c is not reliable in newborns because fetal hemoglobin is present. So it isn’t part of routine newborn metabolic screening. The test that fits the screening purpose is serum amino acids, which are specifically measured by the tandem mass spectrometry panel to detect amino acid and fatty acid metabolic conditions. Tests such as liver enzyme panels or urine electrolyte studies aren’t part of the standard newborn metabolic screen, though they may be used in broader evaluations when indicated.