PKU stands for phenylketonuria, which is a disorder that occurs due to the deficiency of an enzyme called phenylalanine hydroxylase. This write-up provides information on PKU test, which is a blood test that helps in the diagnosis of this genetic disorder.
Phenylketonuria is a genetic disorder that is caused due to the deficiency of a hepatic enzyme that converts phenylalanine into tyrosine. Both phenylalanine and tyrosine are amino acids. PKU test is a blood test that is conducted to check for the presence of phenylalanine hydroxylase in the blood. If this hepatic enzyme is not present in the blood, the level of phenylalanine rises. Phenylalanine then gets converted into phenylketone. Elevated levels of phenylketone can cause damage to the central nervous system and the brain, therefore, this condition must be detected soon. Newborns are screened for this disease through the PKU blood test. If the test results are positive, a geneticist must be consulted at the earliest.
Diagnostic Test for Phenylketonuria
If diagnosed at an early stage, this condition can be kept under control. This is the reason why this test is conducted on newborns. For this test, the blood sample of the infant needs to be collected. A heel stick is used for taking the blood sample of the baby. Blood is taken from the infant’s heel, which is why the heels should be kept warm to increase the flow of blood to the heels. This is to ensure that the blood sample can be taken easily. Since the level of phenylalanine begins to rise about 24 hours after the baby starts drinking breast milk or formula, this test is conducted about a couple of days after birth. If the infant tests positive for this condition, a follow-up blood test is done when the baby is about a week old. For infants older than six weeks, the urine is tested for PKU. 1 mg/dl is considered to be the normal phenylalanine level in blood. When phenylalanine level ranges from 6 to 80 mg/dl, one is diagnosed with PKU. When the levels are consistently greater than 30 mg/dl, there’s a risk of brain damage.
As mentioned earlier, if diagnosed at an early stage, this condition is treatable. Therefore, one must get this test done at the earliest. If left untreated, this condition could manifest in the form of delayed development. A child affected by this condition might suffer from psychiatric disorders or behavioral problems. A musty urine odor, vomiting, irritability, and skin disorders could be attributed to this condition. High levels of phenylalanine can cause damage to the central nervous system. In the absence of treatment, the child might start exhibiting signs of brain damage. Poor concentration, mood swings, depression, mental retardation, seizures, low IQ and slow reaction time could be caused due to high levels of phenylalanine in the body.
Since PKU is a genetic condition, this test must be done in order to find out if newborns are affected by this genetic disease or not. If an infant tests positive, then some other tests might also be conducted in order to confirm the diagnosis. Since this condition is caused due to the elevated levels of phenylalanine in blood, the treatment plan involves the lowering of the levels of this amino acid. The aim of the treatment is to bring down the level of phenylalanine between 2 and 10 mg/dl. Amino acids are required for the growth of the body, which is why the foods that contain phenylalanine cannot be completely excluded from the diet of the affected person. However, one needs to make sure that intake of foods containing phenylalanine is less.
Excessive consumption of foods that are rich in proteins must be avoided. A low phenylalanine diet must be followed for successful management of this metabolic disorder. Dietary guidelines must be followed in order to prevent complications from developing. A nutritionist must be consulted regarding the diet plan that will work best for those diagnosed with PKU. It is essential to monitor the levels of phenylketone and keep them in the recommended range.
If left untreated, PKU can cause mental retardation or intellectual disabilities. Therefore, it is extremely important that people affected by this condition follow a low phenylalanine diet always.
Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.