Disease sexually transmitted:

Primary syphilis

Phenylketonuria (PKU) in children

  • What is Phenylketonuria (PKU) in children
  • What triggers / Causes of Phenylketonuria (PKU) in children
  • Pathogenesis (what is happening) at the time of Phenylketonuria (PKU) in children
  • The symptoms of Phenylketonuria (PKU) in children
  • Diagnosis of Phenylketonuria (PKU) in children
  • Treatment of Phenylketonuria (PKU) in children
  • Prevention of Phenylketonuria (PKU) in children
  • Which doctors should be consulted if You have Phenylketonuria (PKU) in children


What is Phenylketonuria (PKU) in children

Phenylketonuria (PKU) in children mdash genetic disease that is characterized by impaired metabolism of phenylalanine and y 1 from 8000-15 000 newborns. Forms of phenylketonuria (PKU) is only 4, but there are 400 different mutations and metabolic phenotypes of the disease.

PKU mdash - hereditary aminoacidopathy which reduces the intelligence of the child, and there is neurological deficit.

Phenylketonuria (I (classical or heavy) is an autosomal recessive disorder that arises from mutations of the phenylalanine hydroxylase gene. The disease is the lack of the phenylalanine-4-hydroxylase which provides the conversion of phenylalanine to tyrosine, resulting in the accumulation of phenylalanine and its metabolites in tissues and physiological fluids of the child.

A separate group are atypical variants of phenylketonuria. In them the symptoms are very similar to those seen in the classic version of the disease. But no positive progress on indicators of child development, even if you need to conduct a diet. Such options are related to the lack dihydropyrimidinase, tetrahydropyran, guanosine-5-triphosphorylated, 6-pyruvolytetrahydropterin, etc.

Phenylketonuria II (atypical) mdash is an autosomal recessive disease in which the genetic defect is located in the short arm of chromosome 4. It is characterized by a lack of dihydropyrimidinase, which leads to disruption recovery of the active form of tetrahydrobiopterin, and in cerebrospinal fluid and serum reduced levels of folate. The result of such changes – metabolic blocks in the mechanisms of transformation of phenylalanine into tyrosine. The disease was discovered in the late 20th century.

Phenylketonuria III (atypical) mdash is an autosomal recessive disease that is caused by deficiency of 6-pyruvolytetrahydropterin. He participates in the body in the process of creating tetrahydrobiopterin from dihydrogenorthophosphate that was discovered in the late 20th century. Violations similar to those described above (second) form.

Primiparity mdash - atypical phenylketonuria in children with mild hyperphenylalaninemia, which is present in large amounts in the urine premarin and some of its derivatives, and in cerebrospinal fluid normal concentration of neurotransmitter metabolites.

Maternal PKU is a disease which reduces the level of intelligence (up to mental retardation among offspring of women who are sick with phenylketonuria and sat on a special walk, when they were adults.

There are suggestions that in case of maternal PKU disorders in the development of the white matter of the brain responsible for the formation of neurological deficit. A study was conducted in 2008 Cochem and his team. A baby born from a mother with PKU, at autopsy the brain was found a certain amount of pathological changes: ventriculomegaly, low weight of the brain, delayed myelination (signs of astrocytosis was observed), hypoplasia of the white matter.

In some CIS countries applies the conditional classification of the disease under consideration according to the contents in the serum phenylalanine:

The name of the form

The level of phenylalanine


above 20 mg (1200 µmol/l)


A 10.1–20 mg (600-1200 μmol/l)


8 mg (480 µmol/l)


What triggers / Causes of Phenylketonuria (PKU) in children:


The main cause of phenylketonuria in children – lack of an enzyme called phenylalanine-4-hydroxylase. Because of its lack of congestion occurs in the fluids and tissues of phenylalanine in large quantities, which is toxic effect on the Central nervous system of the child. The result is metabolic hormones, protein metabolism, amino acid transport, exchange of Glyco - and lipoproteins.

The cause of PKU in children may be:

  • chronic alcoholism of the mother and/or father
  • contagious inflammation of the genital organs of the parents
  • effect on the body of the father and mother of the adverse factors, etc.


Pathogenesis (what is happening) at the time of Phenylketonuria (PKU) in children:


The pathogenesis of phenylketonuria (PKU) in children is the lack of the enzyme phenylalanine-4-hydroxylase, which provides the transformation of phenylalanine into tyrosine. Derivatives of phenylalanine (phenylpyruvic, phenylacetic, phenylmalonate acid, phenylethylamine, phenylacetylglutamine) and the substance accumulates in the tissues. The consequence is a negative impact on the Central nervous system. This results in various disorders, including in the metabolism of catecholamines and serotonin.


The symptoms of Phenylketonuria (PKU) in children:


The newborn child does not look ill. The symptoms of phenylketonuria (PKU) begin to be noticeable at the age of 2-6 months. Typical symptoms:

  • the lack of interest in the outside world
  • severe lethargy
  • vomiting
  • anxiety
  • irritability

From 6 months the baby is noticeably lagging behind in mental development. A minority of children with mental retardation is mild. And more than half of the children record editio. The growth of the infant with PKU may be normal or reduced. Teething late, the skull may have a size smaller than normal. To sit and walk a child with phenylketonuria starts late.

Children with this diagnosis can be identified by the posture and gait. They are widely legs, bending them at the hip and knee joints. The small steps. When walking, the child sways. They sit in the so-called position tailor – crossed his legs, because they have an increased muscle tone.

In case of phenylketonuria (PKU), children typically have blue eyes and blond shade of hair. The skin is pigmented almost. The child heard "mouse" smell. In some cases the patient can be epileptic seizures, but they go away as the child gets older.

Other typical symptoms of PKU in children:

  • dermographism
  • sweating
  • increased sensitivity to the sun and injuries
  • acrocyanosis
  • severe eczema
  • dermatitis
  • a tendency to constipation
  • hypotension
  • autism spectrum disorders
  • hyperactivity

If you do not spend on time treatment, the level of intelligence of the child will be less than 50. At the age of 18 months can appear seizures. They disappear spontaneously. At an early age, the seizures are often held in the form of infantile spasms, then becomes tonicclonic seizures.

Фенилкетонурия (ФКУ) у детей
Phenylketonuria (PKU) in children


Diagnosis of Phenylketonuria (PKU) in children:


For the diagnosis of phenylketonuria (PKU) in children, determine the blood levels of phenylalanine and tyrosine in blood. Apply the Guthrie test, a sample of Felling, fluorometry, chromatography, MRI, search mutant gene, electroencephalography.

EEG can detect violations mostly in the form of a pattern hypertonie, attacks even if the child was not observed. Also find magic spike - and polyspike-bits (single and multiple). MRI finds no difference signal in the stem, the cerebellum or the cortex. Changes on MRI do not correlate with the level of intelligence, they depend on the content of phenylalanine in the blood.

If your child has phenylketonuria II, the symptoms appear after 12 months of life. In the blood then finding elevated levels of phenylalanine in the neonatal period, prescribed diet, but the disease still progresses. The kids have severe mental retardation, seizures, signs of increased irritability, hyperreflexia, muscle dystonia, spastic tetraparesis. Fatal outcome in some cases occurs at age 2 to 3 years.

The symptoms of phenylketonuria III resemble the above. The child's doctors discover three typical symptom:

  • spastic tetraparesis
  • microcephaly
  • profound mental retardation


Treatment of Phenylketonuria (PKU) in children:


New treatments

Today, researchers are developing several alternative methods of therapy of phenylketonuria (PKU):

  • enzyme therapy by fenilalaningidroksilazy, phenylalaninamide
  • the method of "large neutral amino acids"
  • treatment tetrahydrobiopterin (Sapropterin)

There is information about when patients with moderate or mild form of the disease helped tetrahydrobiopterin at a dose of 10 to 20 mg per 1 kg of body per day. In 2008, it has been proven that normal physical development of children with phenylketonuria can be applied nutritional fractions glycomacropeptide, which also reduces the content in plasma and brain phenylalanine. Experimental method is the injection directly into the affected cells of the liver of the child introduction of the phenylalanine hydroxylase gene. This method is not relevant in the CIS countries, including Ukraine and Russia.

Products for children with PKU (phenylketonuria)

Dietary treatment can prevent intellectual deficits when the classical form of the disease. The importance of the age of the baby when you start to apply the diet. Every month without the use of diet baby with PKU loses about 4 IQ score. Question about diet for phenylketonuria in children in different countries consider different. But with the same principles.

When the level of phenylalanine in the blood to 2-6 mg (120-360 μmol/l) in infants diet is not applied. The essence of the nutritional status of children with PKU – in products with a low content of phenylalanine, mostly non-protein food. For children first year of life. In a later age this diet brings fewer results.

Therapeutic diet in PKU:

  • natural foods
  • therapeutic products
  • malobelkovaya products based on starch

Children with PKU cannot:

  • bird
  • meat
  • dairy products
  • fish
  • breast milk (children under 12 months)

A mixture of children with PKU need with only minimal protein. During the first year of life, the allowable amount of phenylalanine is from 90 to 35 mg/kg of the child. 50 mg phenylalanine = 1 g of protein.

Therapeutic products with phenylketonuria in children:

  • XP Analog LCP
  • MD mil PKU-0
  • Openelec

Diet the child should be followed if the rate of phenylalanine in the blood is low 360-480 mg/DL.

Lure with phenylketonuria (PKU children)

The child reaches the age of 3 months diet need to expand, introducing fruit and berry juices. At first it 3-5 drops, then the volume is increased to 30-50 ml. For children 12 months the dose is up to 100 ml.

Juices as foods:

  • pear
  • Apple
  • plum

Also in the diet gradually introduce fruit puree, gradually increasing the dose. Children from 4 to 4.5 months already can vegetable puree that is cooked by the parents. You can also fruit-vegetable canned food for infants, but without milk. Second complementary foods – porridge (10) from protein-free semolina or sago. Also children can be dairy-free porridge industrial production from corn and/or rice flour. They should be less than 1 gram of protein per 100 ml of the finished product.

Children from 6 months you can enter in diet jelly and/or mousses, in which no protein. They are prepared on amylopectinosis swelling the starch and fruit juice is a low-protein PKU milk drink "Lepromin" and protein-free drink with milk taste Nutrigen.Children with PKU from 7 months you can give a low protein products "Lepromin": rice, spaghetti, spiral. With 8 months with phenylketonuria kids can give special protein-free bread.

Diet for PKU in children from 1 year

To power these patients used products based on mixtures of amino acids without phenylalanine and/or protein hydrolysates or with a meager quantity. In their mapping needs to be complexes of macro-, microelements and vitamins. As children get older, the dose of protein you can increase, but not immediately. The amount of carbohydrates and fats should be reduced gradually, and then completely deleted. The diet is gradually expanding at the expense of natural products and food.

For children with PKU from 12 months you can apply specialized health products:

  • Tetraphen-40
  • Tetraphen-30
  • MD mil PKU-1
  • Tetraphen-70
  • MD mil PKU-3
  • Isipin
  • P S 1, P S 2, P-3 AM
  • XP Maxamum (taste neutral or orange)
  • XP Maxamaid

Doctors suggest that you gradually move to products for older children for 1-2 weeks. The volume of the previous mixture should reduce by 1/4–1/5 and add equivalent amount of new protein product. In part therapeutic foods contain polyunsaturated fatty acids. Among malobelkovaya products of foreign manufacture have drinks without protein, desserts, sauces and condiments, cookies and special breads that you can children with phenylketonuria (PKU).

Some researchers are inclined to the opinion that children with PKU diet needs to be enriched tyrosine. Therapeutic products have a distinctive taste, so they can be desired flavoring without the protein content. You cannot apply the sweetener aspartame, because by splitting it forms including phenylalanine.

When treatment requires regular monitoring of the content of phenylalanine in the blood. Children up to 3 months check 1 time a week, and after obtaining stable results – at least 1 every 2 weeks. Children with PKU from 3 months. to 1 year 1 check once a month, sometimes 2 times. For children 1 to 3 years inspections need at least 1 every two months, and after three years, the control carried out 1 time per 3 months.

The necessary control of such indicators for children with PKU:

  • physical and intellectual development of the child
  • nutritional status of the patient
  • emotional development
  • speech development

Once a month you need to conduct a General analysis of blood. And by indications – biochemical analysis of blood.

If the child detects additional disease with dyspeptic symptoms, intoxication, hyperthermia, then the diet can be discontinued for 2-3 days, replacing medicinal products for natural, not too much protein. When the acute phase of the disease ends in the diet again administered medicinal products, but faster than in the beginning of entering the diet.

Cessation diet

The age of cessation of special diets with PKU in children still in the discussion process. There is information that if you cancel diet at the age of 5, one third of children with PKU was a marked decrease IQ by 10 points or more over the next 5 years. Discontinuation of the diet for children over 15 years in some cases affected the progressive changes of the white matter of the brain, which was diagnosed by MRI.

With classical phenylketonuria in children diet must adhere to a lifetime. Total protein after coming of age should not be more than 0.8–1.0 g/kg per day.

Фенилкетонурия (ФКУ) у детей
Phenylketonuria (PKU) in children


Prevention of Phenylketonuria (PKU) in children:


To assist with early dietary treatment and avoid severe cerebral damage, it is necessary to conduct mass screening for phenylketonuria in the neonatal period. It also avoids the disturbance in the liver of the child. To assess the risk of having a child with the diagnosis, pre-genetic counseling for couples who already have a child with phenylketonuria (PKU) or have relatives with this disease.

Women with phenylketonuria prior to conception should strictly follow the diet and continue it while you're pregnant. This will avoid violations of genetically healthy development of the fetus. The risk of having a child with phenylketonuria the parents are carriers of the defective gene is 1:4.

Children with PKU should be observed as a pediatrician and a neuropsychiatrist.


Which doctors should be consulted if You have Phenylketonuria (PKU) in children:





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