PhenylketonuriaIn order for the body to develop and function, it needs proteins which are consists of special chemical compounds – amino acids. In a healthy body, excessive amounts of amino acids break down into chemical compounds that are not dangerous. In phenylketonuria, a body, due to hereditary deficiency, lacks the enzyme required for the degradation of phenylalanine – one of the amino acids. The main danger is damage to the nervous system due to excessive amounts of phenylalanine in the body of a fetus or a newborn.

In rare cases, when a fetus has phenylketonuria and develops in womb or a mother who also has this disorder, the high levels of phenylalanine in the mother’s body will affect the fetus to such an extent that it will probably be born with a small, deformed brain, and in some cases with cardiac deformation. If the mother is just a carrier of the disorder, which usually happens, or has that disorder, but is on a diet with a minimal intake of phenylalanine, the child with phenylketonuria will be born normal. A special blood test, Guthrie test, is performed in order to detect if the baby has phenylketonuria when it is six days old. If phenylketonuria is detected by blood analysis, treatment begins immediately.

Phenylketonuria is a very rare disease. Today, however, is somewhat more common because modern treatment allows many patients (with this disease) to experience adulthood and have their own children.


A special food (on a bottle) with a low content of phenylalanine is given to the baby immediately. Breastfeeding is not allowed. When the baby begins to take the selected solid food, the milk is still given as this is a source for protein. A child with phenylketonuria must always eat food based on vegetables and salads. In order to obtain the necessary proteins, vitamins and minerals, the diet is supplemented with specially prepared food for children.

A food with low content of phenylalanine is fairly expensive and requires a lot of imagination and careful preparation. Therefore, doctors are trying to determine if, at certain age, the child’s organs have developed so that they can cope with the damage that is caused by high levels of phenylalanine, after which they can safely start with the normal nutrition. Experiments show that a child may move to normal diet at the age of 10 to 12. A woman with treated phenylketonuria, who eats normal food, has to return to a special diet with a low content of phenylalanine before pregnancy, because then the concentration of phenylalanine in her body will then be reduced to an amount that will not damage the baby.