How to Test for PKU

By eHow Health Editor

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Phenylketonuria, abbreviated to PKU, is a genetic disorder marked by a deficiency in the enzyme used to metabolize essential amino acids. Early detection and proper treatment, however, can effectively control the disease. Lucky patients can even approach complete control to the point of a cure.

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Instructions

Difficulty: Moderately Challenging

Detect PKU

Step1

Recognize the symptoms of PKU. They usually begin to show when an infant has reached two to three months of age. A musty odor in the baby's hair, skin and urine will precede vomiting, diarrhea and weight loss. Photosensitivity and skin problems, usually eczema, also result.

Step2

Know that a severe case of PKU will soon result in episodes of screaming, rocking back-and-forth and arm biting in older children. Growth and developmental problems, both physical and mental, accompany a serious or untreated case.

Step3

Test your infant at birth, regardless of whether or not symptoms of PKU are present. Early detection is crucial to preventing irreversible physical and mental deficiencies. In the United States, most babies are tested within two to three days of birth.

Step4

Know that a "heel test," in which a blood sample is taken from the infant's heel, will be done to screen for PKU and other metabolic disorders. It won't hurt your infant and there are usually no complication that result from the drawing of the blood sample.

Step5

Prepare your infant for a PKU test by ensuring it consumes nothing but breast milk or formula for 24-48 hours before the test is performed. Test results are much more accurate when this protocol is strictly observed.

Step6

Be aware that children in excess of six weeks of age will be tested for PKU via a urine test rather than a heel test. A urine test consists of the application of a special test fluid or strip that is applied to fresh urine collected in an infant's diaper. Note that, unlike the heel test, there is no preparation protocol that needs to be followed prior to a urine test.

Step7

Understand that a test for PKU may be performed twice (or more than twice) to ensure its accuracy. Follow-up testing will generally be performed if the first test came back positive. The PKU test is highly sensitive, and accuracy issues are not uncommon.

Tips & Warnings

If PKU is undetected or left untreated, it can result in serious neurological damage, including severe seizures as well as impaired cognitive development and function.