Safe and unsafe duration of fasting for children with MCAD deficiency

To study the safe and unsafe duration of fasting in children with medium chain acyl-Coenzyme A dehydrogenase (MCAD) deficiency, the literature and the database on Dutch MCAD-deficient patients were searched for data on fasting studies in patients with MCAD deficiency.

These data were extended with information on fasting studies performed on our patients with MCAD deficiency known in the Beatrix Children's Hospital, UMC Groningen, The Netherlands. The data reflect considerable inter-individual variation and overlap between safe and unsafe duration of fasting.

In six out of 35 fasting tests, symptoms were reported before hypoglycaemia was observed. Until 1 year of age, the median safe and unsafe duration of fasting was 12 hours (n=7, range 8-19 hours) and 18 hours (n=5, range 15-20 hours), respectively. After the first year of life, the median safe and unsafe duration of fasting was 18 hours (n=17, range 10-24 hours) and 20 hours (n=9, range 13-32 hours), respectively.

Therefore, to conclude, we recommend a maximum duration of fasting in children with MCAD deficiency of 8 hours between 6 months and 1 year of age, 10 hours in the second year of life and 12 hours thereafter. From this study, no conclusions can be drawn on the duration of fasting during situations of intercurrent illness, especially with fever.