Potential problems

Anorexia, refusal to eat

Infants and/or little children can reject food at certain times without being ill:

  • if he or she refuses to eat, do not get anxious and do not try to get your child to eat for an hour or more, and do not reheat the plate or resort to “tricks” to get your child to eat: TV, games, bringing in different people, forcing, etc. You should rather take the plate away and refrain from bringing dessert. That way, your child will be hungry and much more open to eating at the next meal. If your child sees you anxious, this attitude may become more common:
  • do not give in, not even by giving him or her other low protein foods instead;
  • spread out the parts of leucine that your child has not taken with this meal among the other meals of the day;
  • do not give your child small amounts of forbidden foods to get him or her to eat or to make him or her happy: your child cannot understand that some things are partly allowed or that a food that is allowed today is forbidden tomorrow. Furthermore, he or she will only get a tiny amount! And you will need to compensate his appetite with hypoproteic foods he or she will soon get fed up with.


Mom and Dad need to be on the same page on this because, if your child sees you react differently, anorexia and/or refusal to eat may become entrenched.

Make sure that you are giving your child the right amount of the mixture of amino acids. An excessive amount can reduce your child’s appetite.

If your child has a small appetite, your dietitian will look at the possibility of choosing a mixture with fewer calories with you.


Refusal to take the mixture of amino acids

Your child may refuse to take the mixture of amino acids. This may be due to the preparation method:

  • if the mixture is too diluted, the volume may be excessive,
  • whereas if it is too thick, it may be too concentrated.


If there is repeated failure to take the mixture or, even worse, if the child refuses to take it, his or her blood concentration will inevitably become unbalanced. Your child must understand that the mixture is essential to his or her well-being and that it is part and parcel of his or her diet: your child must take it every day.

Refusing to take the mixture is more likely if the child sees the parents concerned about it, because they know it is important. If the situation is too difficult for you, ask a psychologist for help; he or she will provide reassurance and advice.

If the child refuses to eat fruits and vegetables or take the mixture of amino acids, do not give in —it is important for the health of your child. Failing to follow the diet consistently, with diverging attitudes, will quickly lead to toxicity and increased blood concentrations, with the resulting health problems.


Intercurrent diseases

In children with maple syrup urine disease, straying from the diet, eating less and intercurrent diseases all heighten the risk of acute decompensation from the moment leucine levels exceed a certain threshold.

In this case, it is crucial to prevent acute episodes by strictly following the diet and adjusting it whenever special circumstances that can increase blood concentrations occur. Watch out for situations that could trigger decompensation.

Potential decompensation triggers:

  • fever, nose and throat infections, colds, bronchitis,
  • teething, otitis,
  • gastrointestinal disorders: vomiting, diarrhoea,
  • anorexia, fasting
  • errors and/or deviations from the diet,
  • refusal to take amino acids mixes,
  • failure to gain weight or, even worse, weight loss
  • vaccinations;
  • general anaesthesia, surgery, accidents, trauma,
  • chronic leucine deficiency,
  • valine and/or isoleucine deficiency.


Decompensation can also occur without any apparent cause. It is important to be aware of clinical warning signs:

  • In babies, the first signs are feeding problems, vomiting, and the baby being limp, lethargic and easily tired.
  • Older children have coordination and walking problems, as if “drunk”. Their demeanour can be unusual and they can be lethargic or, on the contrary, agitated.


At school, they may have speaking or writing problems, mix up the letters in a word or “skip” a word during a dictation. They can experience unusual episodes of nausea or anorexia. If you see one of these signs or go through a situation with high risk of decompensation:

  • carry out a ketones urine test to determine whether your child is in a catabolic state (where the body breaks down its own protein and, therefore, releases amino acids);
  • see your doctor to screen for a potential infectious cause;
  • adapt your child’s diet if his or her appetite stays the same and minor clinical signs appear following vaccinations, or in the event of well-tolerated low-grade fever while waiting for blood tests, and implement a “semi-emergency diet” if prescribed by your healthcare centre.
  • have plasma levels of leucine, valine and isoleucine checked urgently.

On the other hand, if the fever gets higher or your child gets sick, the diet needs to be adjusted as prescribed.  The semi-emergency or emergency diet reduces or eliminates natural protein altogether while increasing the calorie content of the diet (e.g. enriching dishes with sugars and fats, using hypoproteic products). It may make sense to have smaller, more frequent meals to help your child to eat and limit vomiting. Your child must continue to take the mixture of amino acids during these episodes.

ALWAYS call your reference HOSPITAL.

Your dietitian or doctor will give you the results of the blood tests and tell you for how long you need to maintain the emergency diet, as well as whether you need to give your child valine and/or isoleucine supplements. This diet should not last more than 3 or 4 days.

It must not be repeatedly applied at home without seeking the advice of attending physicians, as it could be counterproductive. If even the slightest fever causes a switch to the “emergency” (zero-leucine) diet just to be “on the safe side” and avoid an increase in leucine levels, the cumulative intake of your child will be insufficient for adequate growth.

If, after this period (or even before) and despite these measures, your child’s clinical signs persist or get worse (impaired consciousness, vomiting or complete refusal to eat), take your child to hospital straight away.

Your child may need to be put on continuous enteral nutrition (CEN) in hospital. Your documents must include an emergency diet to be given by nasogastric intubation. It needs to be updated regularly as your child grows.

If your child is admitted to a community hospital, it may not necessarily have the products needed to prepare the emergency diet. Do not forget to provide all necessary products, including the mixture of amino acids and the “recipe” for the emergency diet. You can also offer to prepare it yourself. CEN usually resolves the metabolic imbalance on its own.

On the other hand, if your child has significant gastrointestinal problems, particularly uncontrollable vomiting, all or part of the treatment may need to be given by intravenous infusion.

Keep in mind that any delay in seeking care for decompensation can have serious consequences.


In conclusion, the management and prognosis of your child will be best if you follow the basic rules: “controlled” intake of natural protein and, therefore, leucine, taking a mixture of essential amino acids, and maintenance of sufficient caloric intake thanks to hypoproteic foods. Situations that increase the risk of acute decompensation must be prevented whenever possible.  Do not hesitate to get in touch with your reference care team if you have any questions or doubts: their role is to take care of your child, and this requires regular communication with you.