MCADD - Newcastle Hospitals NHS Foundation Trust

Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD)

MCADD is an autosomal recessive inherited enzyme deficiency which reduces the ability to effectively metabolise fat into energy. It affects 1 in 10,000-20,000 babies in the UK.

During long periods between eating the body breaks down fat stores to produce energy. Those with MCADD cannot break down fats completely which leads to a build up of metabolites at the medium chain fats level which are toxic. MCADD is treated by diet.

Within the Northern Region, the family of a screen positive baby will be contacted via the Specialist Team to discuss the result and further management and to arrange a meeting with the team within 24 hours of the positive test.

The GP will also be contacted by the Specialist Team to discuss the result and any further action that may be required by the Primary Care team prior to the family meeting the Specialist Team. Information will be sent to the GP.

The baby will require further tests to confirm the diagnosis which will include blood and urine tests. Once the diagnosis has been confirmed, screening of any siblings will be offered.

A child with MCADD is at risk from hypoglycaemia, coma and death with prolonged fasting and especially during intercurrent illness (for example diarrhoea and vomiting), when the demand for energy increases and calorie intake is often reduced.

If a child is decompensating they may appear drowsy and lethargic, they may vomit, have seizures and have a deteriorating conscious level. Hypoglycaemia is a late sign; so treatment should be started if the patient is unwell, even if the blood sugar is normal.

A patient with MCADD requires no special treatment when well, apart from avoiding prolonged fasts. Breast feeding is not contraindicated, but it is important to ensure that the baby is feeding well. The baby should be fed 3 to 4 hourly day and night or more often if demanded. The baby should not fast for longer than 6 hours.

Families will be taught how to use an Emergency Regimen (ER) of very frequent drinks during intercurrent illness. Details of the ER will be sent to the GP. The aim of the ER is to provide readily available calories to avoid the mobilisation of fat stores which could lead to decompensation.

Oral rehydration therapy (ORT) solutions don’t contain sufficient calories to avoid decompensation and if used need to have glucose polymer added. The family and the GP will have a recipe how to do this. If the ER is not tolerated, or the child does not improve, then urgent admission to hospital will be needed to enable the child to receive an intra venous infusion of 10% dextrose and electrolyte additives. Parents and the GP will be given a letter by the Specialist team to show A&E/hospital detailing the condition and what treatment is required.

The long-term prognosis for MCADD is very good once diagnosed, providing that the children eat regularly and avoid long periods without food, and if poorly that the emergency regimen is followed. Immunisations should be undertaken as normal and general care is unaffected.