PHENYLKETONURIA

PKU Full Form: Phenylketonuria

Prevalence of PKU in India:

The occurrence of PKU varies among ethnic groups and geographic regions worldwide. In the United States, PKU occurs in 1 in 10,000 to 15,000 newborns. Most cases of PKU are detected shortly after birth by newborn screening, and treatment is started promptly. As a result, the severe signs and symptoms of classic PKU are rarely seen. With increasing awareness of newborn screening in India, detection of PKU has strengthened. Phenylketonuria (PKU) was the first inherited metabolic disease in which dietary treatment was found to prevent the disease’s clinical features.

Phenylketonuria Definition:

Phenylalanine is an essential amino acid. When phenylalanine crosses the threshold levels in the blood, the excess is seen in the urine. This is the meaning of phenylketonuria or PKU.


Phenylketonuria Causes:

Dietary phenylalanine is normally degraded by the way of the tyrosine pathway. PKU is an enzyme defect. Deficiency of the enzyme phenylalanine hydroxylase (PAH) or of its cofactor tetrahydro-biopterin (BH4) causes accumulation of phenylalanine in body fluids and in the brain. This abnormal increase in phenylalanine is detrimental to health and survival. The severity of hyperphenylalaninemia depends on the amount of enzyme available.

In affected infants & children, excess phenylalanine in the blood is metabolized into phenylketones. These are excreted in the urine, giving rise to the term phenylketonuria.

PKU Symptoms:

Newborns with phenylketonuria initially don’t have any symptoms. Without treatment, babies usually develop signs of PKU within a few months. Phenylketonuria symptoms can be mild or severe and may include:

  • Intellectual disability,
  • Delayed development,
  • Behavioral, emotional and social problems,
  • Psychiatric disorders,
  • Neurological problems that may include seizures, hyperactivity
  • Poor bone strength,
  • Skin rashes (eczema),
  • A musty odor in the child’s breath, skin or urine, caused by too much phenylalanine in the body,
  • Fair skin and blue eyes, because phenylalanine cannot transform into melanin — the pigment responsible for hair and skin tone,
  • Abnormally small head (microcephaly)

PKU Test:

Phenylketonuria patients are diagnosed by screening with tandem mass spectrometry (TMS). 5 drops of blood are taken from the baby’s heel and collected on special filter paper. Infant must be 48 hours of age or older to obtain a satisfactory sample for screening. Ideal time is 4 days of age. Sample should be taken prior to administering antibiotics or transfusing blood or blood products.

TMS being the primary test should always be backed with a GC-MS (Gas chromatography mass spectrometry) test to reconfirm the diagnosis. GC-MS is gold standard technology for confirming PKU disorder.

PKU Treatment:

When phenylalanine from the diet exceeds the threshold, it saturates the blood-brain barrier and can cause cognitive delay, neuropathy and delayed growth and developmental milestones.

When phenylalanine levels are managed, however, all these complications can be avoided. Phenylketonuria once diagnosed requires a phenylalanine-free diet treatment only then is normal physical and mental development possible. However, PKU patients do require a small amount of phenylalanine, because this amino acid is essential for life.

PKU Diet in India:

Amino acid formulae made without phenylalanine is imperative in order to prevent muscle proteins from breaking down for energy utilization, especially on a low protein diet. This aids in maintenance of the body weight & development. Hence, PKU patients require special diets. Pristine Organics offers Phenylalanine free diets at 15%, 60% and 85% Protein levels depending on the patients’ needs in India. The optimum amount of Pristine Balance Metanutrition PKU diet is calculated based on the child’s age and body weight and is constantly adapted to his or her needs.

For weight gain and developmental growth, additional sources of nutrition are essential. Protein free calorie rich formulae, nutridense and low protein foods need to be given to meet 100-125% of the RDA per age. Providing education and support for the family is the key to a successful long range of therapy. Effective treatment is best achieved by a team of specialists such as your Physician, Nutritionist, Geneticist, Neurologist, and Psychologist.

A healthy Phenylketonuria life expectancy can be foreseen with a wholesome approach including a watchful diet, medical support and optimal nutrient supplement.