A small number of newborn babies (around 1 in 4,000) may suffer from a condition known as "inborn errors of metabolism". Metabolic diseases are caused by faulty genes which result in a lack of a particular enzyme, thereby hindering metabolism. The effects include a lack of essential substances for the body or the accumulation of toxic substances. If these diseases are not treated early, they can lead to serious consequences, including developmental problems during growth, learning difficulties, intellectual disability, and in severe cases, permanent physical disability or even death.
Most newborn babies who are ill have no obvious symptoms at birth, and these symptoms are often difficult to detect or easily mistaken for other infant illnesses. These include poor appetite, vomiting, muscle weakness, lethargy, developmental delay, and even seizures or sudden death. If detected and treated early, serious and long-term effects on the baby's health and development can be avoided.
In the present era, metabolic disease screening methods are mainly divided into two types: blood or urine screening. The difference between the two lies in the number of metabolic diseases detected and their invasiveness. Blood screening detects about 30 metabolic diseases, including amino acid disorders, fatty acid oxidation disorders, and organic acid disorders. However, metabolic diseases are numerous, and not all are included in the screening. The method is simple: a few drops of blood are collected from a heel prick on the baby's foot onto filter paper for testing. Generally, infants need to have been feeding for at least 1 day and blood should be drawn between birth and 7 days old. The results can be known in just a few days. Urine screening, on the other hand, uses different screening methods.
Dr. Chan Yan Wing, Paediatrician
