Maple Syrup Urine Disease
Maple Syrup Urine Disease is a life threatening condition if it is not detected and treated early. It is an autosomal recessive disorder caused by a defect in the metabolism of the three branched chain amino acids. Approximately one in every 125,000 babies born in Ireland may have this condition or about one baby every two years. The disorder is so called because the urine may have an odour similar to that of maple syrup.
Screening was originally justified on the basis that chronic physical and intellectual handicap and premature death had occurred in a number of families where this condition had gone undetected. The branched amino acids accumulate in the blood following the establishment of feeding and these high levels cause brain damage.
A diet similar to that for PKU but with low levels of the offending amino acids is started as soon as the diagnosis is made. Normal brain development and good health result from early treatment; life long adherence to the diet is mandatory. However, urgent medical intervention may be required during acute illnesses, such as infections or ‘stress’.
Some variant forms of Maple Syrup Urine Disease may not be detectable in the newborn period and may present clinically later in life.
Action following detection of raised result
When the bloodspot leucine (including isoleucine) is raised, MSUD is suspected; the following clinical procedure is implemented:
1. The test results are discussed with the On-call Consultant Metabolic Paediatrician and a decision made as to where and when the child should be admitted as an inpatient. .
2. The Clinical Liaison Officer (NNBSL) will:
- contact the paediatric registrar associated with the Maternity Unit in which the baby was born. Clear instructions are given to include the child’s demographic details, the condition suspected and the arrangements for admission. The Registrar is asked to contact the parents and inform them that their baby may have one of the metabolic conditions screened for as part of the heel-prick test. The Registrar is asked to arrange immediate admission either to Temple Street or to the local Neonatal Unit as advised by the NNBSL
- contact the on-call metabolic medical scientist to inform them to expect a sample for branched chain amino acids
3. The local paediatric registrar is asked to contact the On-call Consultant Metabolic Paediatrician to discuss the management of the baby on arrival.
4. Once the baby has been admitted and clinically examined, the urine should be tested for the presence of ketones and a blood sample obtained and sent urgently to the Metabolic Laboratory at Temple Street for amino acid analysis.
5. If the diagnosis is confirmed the infant may need to be transferred to the Children’s University Hospital once the infant’s condition has been stabilised.
Once the diagnosis has been confirmed the screening process is complete