MCADD is a rare life-threatening genetic disorder present from birth. It stands for “medium chain acyl-CoA dehydrogenase deficiency”. In MCADD, the body is unable to break down medium chain fats which come from food and also from fats already stored in the body. Most fats in our diets are long chain fats and can be broken down without any difficulty.

Energy from fat keeps us going whenever our bodies run low of their main source of energy, a type of sugar called glucose. Our bodies rely on fat when we don’t eat for a stretch of time – like when we miss a meal or when we sleep. In MCADD, however, the body cannot break down fat for energy. Instead, it must rely solely on glucose. Although glucose is a good source of energy, there is a limited amount available. Once the glucose has been used up, the body tries to use fat without success. This leads to low blood sugar, called hypoglycaemia and to the build up of harmful substances in the blood, which causes liver and muscle problems.

At present, the mainstay of treatment for MCADD is to have frequent carbohydrate meals and snacks throughout the day. Patients will be told how long it is safe to fast for and this will increase as the patient gets older.

During times of illness, the body will break down its own tissue to provide energy (catabolism). This can be dangerous for people with MCADD as levels of certain fats and other harmful substances will increase quickly and blood sugars will drop. When unwell, it is necessary for patients to eat carbohydrate foods and drinks more frequently. Patients will be provided with an individualised emergency plan to use when they are unwell.

Many countries screen newborns for this condition.  In Ireland, screening for MCADD was added to the National Newborn Bloodspot Screening Programme on December 3rd, 2018. At the NCIMD, we have been treating patients with MCADD for a number of decades and have significant experience of managing this disorder. Patients with MCADD are managed by the multidisciplinary team. We follow international best practice guidelines in managing our patients with MCADD.

Printable/Downloable Resources
MCADD Handbook

MCAD Standard Emergency Letter

Emergency regimens:
Emergency Regimen for formula feeding infants less than 1 year

Emergency Regimen for breastfeeding infants less than 1 year

Emergency Regimen for 1-2 year olds

Emergency Regimen for 2-10 year olds

Emergency Regimen for 10-16 year olds

Emergency Regimen for adults