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What are the Most Common Phenylketonuria Symptoms?

Tricia Christensen
Tricia Christensen
Tricia Christensen
Tricia Christensen

In many parts of the world, most people will never see the common PKU or phenylketonuria symptoms because many countries routinely test for this genetic disorder in the first few days of life. Though uncommon, the condition is extremely severe when untreated and it can begin to cause serious lifelong side effects within a few months of birth. The emphasis behind testing every newborn is to make certain those who have PKU get immediate treatment in the form of a low-protein diet that lacks phenylalanines, which build up otherwise and create damage. Early intervention is key to prevent all phenylketonuria symptoms and to give people the opportunity to live relatively normal lives.

When this testing is not available or is only optional, a number of phenylketonuria symptoms in the child with PKU begin to emerge when a child is just a month or two months old. Parents may notice children have excessive diarrhea or vomiting, which causes poor weight gain and may cause failure to thrive. Another of the phenylketonuria symptoms may seem much less obvious to people. Babies may be light sensitive, which is true of a lot of babies. Parents should look for excessive light sensitivity, but this may not be the best diagnosing factor.

Babies with phenylketonuria often exhibit symptoms similar to colic.
Babies with phenylketonuria often exhibit symptoms similar to colic.

The baby with phenylketonuria symptoms is also characterized as being very fussy or difficult. Such children may cry much more frequently, which sometimes gets dismissed as colic. Not as easy to dismiss is persistent skin problems like dryness or eczema that may be profuse. Additionally, babies with PKU often have a peculiar smell, which is described as almost musty or moldy. This smell may also be present in urine, and differs very much from the typical baby smell.

Children with PKU must inherit a recessive gene from both parents in order to acquire the condition.
Children with PKU must inherit a recessive gene from both parents in order to acquire the condition.

Should these phenylketonuria symptoms not be recognized, the condition gets far worse over the course of a few months. The growing levels of phenylalanines in the body, which can’t be broken down or excreted, begin to cause severe brain damage. This might be expressed with failure to meet any or all developmental milestones, self-injurious behaviors like banging the head, growing retardation that can quickly become profound, and occurrence of seizures. The emergence of these symptoms is usually indication of PKU, but hopefully its earlier indications have led to treatment.

Phenylketonuria symptoms may include light sensitivity.
Phenylketonuria symptoms may include light sensitivity.

When phenylketonuria symptoms are recognized early, it is possible through diet alone, to avoid the difficult challenges faced by those with undiagnosed PKU. Though a phenylalanine free diet can be restrictive, it usually means a person who is on such a diet after early diagnosis does not suffer the extremes of PKU. Cognition remains strong, developmental milestones are reached on time, and few disabilities exist. This is undoubtedly the best argument for making a diagnosis early. To treat this condition before damage starts to accrue is highly desirable.

Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent WiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

Learn more...
Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent WiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

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    • Babies with phenylketonuria often exhibit symptoms similar to colic.
      By: Galina Barskaya
      Babies with phenylketonuria often exhibit symptoms similar to colic.
    • Children with PKU must inherit a recessive gene from both parents in order to acquire the condition.
      By: Monkey Business
      Children with PKU must inherit a recessive gene from both parents in order to acquire the condition.
    • Phenylketonuria symptoms may include light sensitivity.
      By: petarpaunchev
      Phenylketonuria symptoms may include light sensitivity.
    • Untreated PKU can result in seizures.
      By: elenarostunova
      Untreated PKU can result in seizures.
    • Children with PKU may experience seizures.
      By: Photographee.eu
      Children with PKU may experience seizures.
    • Phenylketonuria symptoms may include persistent skin problems like eczema.
      By: Jingling Water
      Phenylketonuria symptoms may include persistent skin problems like eczema.