Phenylketonuria - congenital disorder requiring lifelong special diet

 Phenylketonuria is a disorder of metabolism of amino acid. This congenital disorder is a hereditary disease. As a result of this disease phenylalanine accumulates in the blood, its increased amount in the body is dangerous, because it causes irreversible neurological damage, including mental retardation. Initiation of therapy within a few days after the birth of a child with this disorder is very important, because in this period the infant's brain develops most.

Phenylketonuria is disease diagnosed from collection dry drops from the heel of the new-born. Treatment then consists in very strict dietary restrictions natural proteins in food with the calculated dose of phenylalanine in such a way that the patient is able to metabolize and prevent its rise in the blood.

If is phenylketonuria not treated, it states that it may reduce a child's IQ by as much as half. Children suffering from phenylketonuria are getting special milk substitute. Thereafter their diet is low-protein, mostly vegetarian. Of the diets of children are excluded all protein-rich foods, i.e. meat and meat products, milk and dairy products, cereals, eggs, legumes, bakery products, chocolate and many other foods. The base diet for all patients suffering with phenylketonuria are especially potatoes, vegetables, fruits, vegetable fats and oils, low-protein pasta and other products that have low protein content.

Health symptoms of phenylketonuria in children

  • Convulsions, convulsions seizures
  • Problems with receiving food
  • Vomiting
  • Albinism - very light skin, light eye colour, melanin deficiency
  • Smell of musty thing or mouse smell: urine and sweat child smells unpleasantly, later the odour typical for this disease is also in hair
  • Retarded child development: increased amount of phenylalanine in the body and brain of a child leads to gradual development of mental retardation, a child starts to lag behind their contemporary
  • Microcephaly: smaller size of the baby's head is related to the development of mental retardation
  • Hyperactivity: this may appear as one of the symptoms of damaged brain functions
  • Changes in the EEG: brain function disorder, abnormal electroencephalogram recording
  • Eczema

Medical symptoms in adult phenylketonuria

  • Tiredness
  • Impaired concentration and thought
  • Memory Disorders
  • Reduced performance
  • Nervousness
  • Moodiness
  • Anxiety disorders
  • Other mental problems

The discovery of phenylketonuria and history of its treatment

Norwegian physician and biochemist Asbjorn Föllinge (1888-1973) was engaging in his researches and works in metabolic disorders and became the first who diagnosed phenylketonuria. In 1933, he was asked to cooperate and help doctor Egeland to explain mental retardation of two siblings. Folling conducted a series of tests in children. Among others, he also tested in these children their urine, conventional tests were normal, but during the urine test for ketones content, the urine, after the adding ferric chloride, instead of becoming red-brownish, as expected, its colour turned into green. He never experienced similar reaction before.

This unusual finding caught his attention and that is why professor Follinge decided isolate this unknown substance and specify it. He suspected that it might be the cause of mental disability in both children. In collaboration with their mother, he collected during the week of 20 litres of urine of children and developed a way to isolate this substance. During the following weeks, was the substance isolated. This substance was phenyl pyruvic acid, this acid gave name to a new illness - Imbecilitis phenylpyruvica. Folling decided to find out if the finding of phenyl pyruvic acid in the urine is linked to children mental retardation. He decided to examine with this simple test urine of 400 children in an institution for the mentally disabled in Oslo. He found here another eight children, including two siblings with the same findings in urine. In the notes, inter alia, he noted that these children also have other common characteristics such as: pale skin, skin rashes, broad shoulders, stooped posture, spastic gait and a characteristic odour. All of them also suffered with intellectual impairment. In 1934, he published his famous publications dealing with this newly discovered metabolic disorder. During his other researches, together with geneticist Louis Mohr, he discovered another 34 patients from 22 different families, according to genealogical data was phenylketonuria included as an autosomal recessive genetic disease.

Folling dealt with phenylketonuria onwards, he assumed that the amount of phenyl pyruvic acid in the urine is the result of the inability to metabolize the amino acid phenylalanine. To confirm this hypothesis, he needed to measure accurately the amount of phenylalanine in the blood. With his colleague, Karl Closs, they found the bacteria Proteus vulgaris, which converts phenylalanine to phenyl pyruvic acid. The following tests on the amount of phenylalanine in the blood of patients confirmed Folling's initial theory. Phenyl pyruvic acid was also responsible for the characteristic odour of patients. For his discoveries, Follinge received many prestigious awards.

Less than 20 years after the discovery of the phenylketonuria was this disease well known in the scientific community as indigestion of proteins that could be regulated by a special diet. In 1951 was for the first time in history established therapeutic diet for phenylketonuria (PKU) patients, based on reduced phenylalanine content in the diet. Its use has led to excellent results and a positive effect. Over the next fifty years was this fact many times confirmed. We can say that even today remains the elimination diet the only way, how we can widely, and successfully treat phenylketonuria.

Disease phenylketonuria today

Diagnosis of phenylketonuria is nowadays done with the help of all-over screening in new-borns. The baby is taken droplet of blood, from which it determines level of phenylalanine in plasma. Initiation of treatment is necessary to make as soon as possible, to reduce the risk of pathological disorders. The diet must then be adhered throughout life, but in adulthood, it is not as stringent as in childhood and adolescence. For patients with phenylketonuria is very important factor the protein, therefore, was for the patients with this disorder created special protein preparation free from phenylalanine. The nursing physician determines the quantity, which is suitable for individual patient to receive.

Adequate diet is initiated immediately after detection of disease phenylketonuria. Breastfeeding is not suspended completely, it is only reduced. Phenylalanine as such is also important for the development of human body. Its shortage appears in reduced weight gain, in feeding problems and skin lesions. Negative consequences and manifestations of lack of phenylalanine can also be lethargy, infections, digestive discomfort, and swelling.

Diet during phenylketonuria

During phenylketonuria diet are from diet strictly excluded foodstuff with high level of phenylalanine. Patients cannot eat meat, fish, milk, and dairy products, hence no cheese, eggs, and cereals including rice. It is not strictly limited to eat foods with low level of phenylalanine: some fruits and vegetables. These are apples, apricots, cherries, fresh figs, gooseberries, grapefruit, grapes, lemons, tangerines, melons, nectarines, oranges, peaches, pears, pineapple, plums, raspberries, and rhubarb. Of vegetables are recommended artichoke, eggplant, cabbage, carrots, cauliflower, celery, chicory, cucumber, leek, pepper, pumpkin, radish, and tomato. Then there are foods, which have medium content of phenylalanine, and it is necessary to count phenylalanine intake from them. For examples: potatoes, spinach, broccoli and specially produced bread and pasta for patients diagnosed with FKU.

Women, who are planning a family, and are diagnosed with phenylketonuria, should reduce the amount of phenylalanine already 3 months before a planned conception. Phenylalanine should be then reduced throughout the whole pregnancy. When s the levels of phenylalanine increased in the mother's body, it passes through the placenta and amino acid can affect a child's development and irreversibly harm the foetus. It is appropriate to consult with doctor what levels of phenylalanine must each mother adhere.

It is necessary to be aware of the sweetener called aspartame. Products, which contain it, should be labelled "not suitable for people suffering with phenylketonuria". Aspartame is in the human body converted into methanol (about 10%) and two amino acids - 50% phenylalanine and 40% aspartic acid. It is important to keep an eye on it and avoid these foods, which contains aspartame.

Phenylalanine content in food can be detected by a simple calculation. Find the amount of proteins in food. Proteins are given per 100 g of the product. Multiply this number of proteins with the amount that we plan to eat. The number that we get this way either multiply by 50 - we assume that 1 g of protein contains 50 mg of phenylalanine (if we do not have the food table) or you can find the content of phenylalanine per 1 g of food (you can find it in the food tables). According to the result, we will consider whether it is suitable food to eat or not.

People diagnosed with a disorder of phenylalanine metabolism often suffer from deficiencies of vitamins and minerals. Lack of these substances in the body appears, for example, as a anaemia or osteoporosis. Most often, it is vitamin A and some B vitamins, from mineral substances it is especially lack of calcium, zinc, iron, iodine, and selenium. This kind of food should be replaced.

Phenylketonuria is a rare incurable disease. Early diagnosis is recognized by all-over screening of new-borns. If it is treated in early stages, the damage to the body is prevented. The disease can be compensated by diet, although compliance of the diet is not easy. Normal diet is up to 50% cheaper than special diet low in phenylalanine. Nowadays, there are many products that are intended for patients with FKU and thanks to them can be diet for people suffering with this disease much richer.

Successful compensation of disease depends very much on the cooperation of the patient with the doctor. Diet must be adhered for a lifetime. In adulthood, the diet is generally less severe than in the early years. Women planning a pregnancy should be properly informed about the risks of high levels of phenylalanine in the body of the child.


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