Also indexed as:Folling’s Disease, PKU
Early diagnosis is key to treating PKU, a rare genetic disorder that results in an amino acid imbalance in the body. According to research or other evidence, the following self-care steps may be helpful.
Phenylketonuria: Main Image

About This Condition

Phenylketonuria (PKU) is a rare genetic disorder that results in excessive accumulation of the amino acid, phenylalanine, and reduced levels of the amino acid, L-tyrosine, in the blood.1

If untreated, high levels of phenylalanine can cause severe mental retardation, behavioral disturbances, and other brain and nerve problems. Fortunately, newborn screening programs now identify most cases of PKU in the United States and other countries. Early diagnosis and treatment is the key to reducing or preventing PKU-related conditions.2 Gene therapy is currently being researched as a possible cure.3, 4 Research is also being conducted on methods to decrease levels of phenylalanine in the blood through the use of certain enzymes5 and amino acids.6


Infants with PKU may be lethargic, feed poorly, and have a “mousy” odor from their sweat and urine. Eczema, sensitivity to sunlight, and light skin are also characteristic of PKU. Symptoms of children with untreated PKU include significantly diminished mental capacity, hyperactivity, and seizures.

Healthy Lifestyle Tips

Access to PKU resource/support groups, and education of family members may help simplify the complex dietary restrictions and improve one’s ability to follow them.7, 8, 9

PKU during pregnancy (maternal PKU) is of particular concern. Excessively high or low levels of phenylalanine may occur during pregnancy, both of which may adversely affect the fetus.10 Maternal PKU can lead to fetal malformations, including small head size (microcephaly), heart abnormalities, failure to grow properly in the uterus (called intrauterine growth retardation), and mental retardation.11 Adverse effects on the offspring can be reduced and by careful dietary control both prior to and during pregnancy.12, 13, 14Consultation and follow-up visits with medical and nutritional specialists are necessary for effective monitoring and dietary guidance in people with PKU.

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The information presented by TraceGains is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2023.