Is phenylketonuria related to jaundice?

Written by Wu Ben Rong

Pediatrics

Updated on May 01, 2025

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Phenylketonuria (PKU) and jaundice are unrelated, as the causes of these two conditions are fundamentally different, constituting two completely distinct types of diseases. Phenylketonuria is usually caused by a metabolic abnormality, primarily due to abnormal metabolism of phenylalanine in the body, and it is usually a genetic disease. Jaundice, on the other hand, is primarily caused by an abnormal metabolism of bilirubin. Although both diseases occur frequently in infants and young children, there is no essential correlation between the two diseases. It is recommended that regardless of the disease, parents should give adequate attention, promptly take their children to a reputable hospital for relevant examinations, and seek timely treatment.

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Written by Tong Peng

Pediatrics

1min 1sec

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Does phenylketonuria easily cause a cold?

Phenylketonuria does not easily cause a cold, as a cold is a type of infectious disease mainly caused by various pathogen infections and stimuli, leading to symptoms such as cough, fever, and runny nose. Phenylketonuria is a common amino acid metabolism disorder caused by a deficiency of the enzyme required for phenylalanine to convert into tyrosine, resulting in excessive excretion of phenylalanine in urine. This disease is a recessive hereditary disorder, which can lead to intellectual disability, neuropsychiatric symptoms, and pigment loss. Due to the lack of melanin, affected children often present with yellow hair, pale skin and sclera, and their urine has a mousy odor. They may also suffer from eczema, vomiting, and diarrhea. Phenylketonuria is one of the few treatable hereditary metabolic diseases, so it generally does not cause symptoms of a cold.

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Written by Zeng Hai Jiang

Pediatrics

50sec

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What tests do parents with phenylketonuria undergo?

Parents with phenylketonuria can undergo chromosome testing. Phenylketonuria is a common amino acid metabolic disease and an autosomal recessive genetic disorder. Currently, it is mainly screened after the birth of the child by testing the blood for phenylketonuria. Phenylketonuria can also be screened prenatally before the birth of the newborn. Screening can be conducted by extracting amniotic fluid from the pregnant woman for genetic screening through amniocentesis between the 16th and 20th weeks of pregnancy. If chromosomal abnormalities are detected through amniocentesis, it indicates that the fetus carries the pathogenic gene, proving that the child will have phenylketonuria after birth. Couples carrying related genes also need to undergo prenatal screening.

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Written by Yan Xin Liang

Pediatrics

48sec

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Phenylketonuria lacks what enzyme?

Phenylketonuria is an autosomal recessive genetic disorder primarily caused by mutations in the phenylalanine hydroxylase gene. This leads to reduced activity of phenylalanine hydroxylase, accumulation of phenylalanine and its metabolites in the body, and the onset of the disease. Phenylketonuria is the most common congenital amino acid metabolism disorder. Clinically, it is mainly characterized by intellectual developmental delays, light skin and hair pigmentation, and a mousey urine odor. The incidence of this disease varies by ethnicity and region. In China, the incidence is approximately 1 in 11,000.

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Written by Yan Xin Liang

Pediatrics

1min 3sec

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Phenylketonuria positive means what?

Phenylketonuria is an autosomal recessive inherited disease and is the most common congenital amino acid metabolism disorder. Generally, if the activity of phenylalanine hydroxylase in the body is reduced, or if there is a deficiency in its coenzyme tetrahydrobiopterin, the concentration of phenylalanine in the blood and tissues will increase, and phenylpyruvic acid, phenylacetic acid, and phenyllactic acid in the urine will also increase. Generally, newborns may not show any special clinical features at first. Often, the first test results may be high due to maternal influence or dietary factors, which can cause these elevated indicators in newborns. If the second test is normal, there usually isn’t a significant problem. A third test can also be performed; if the third test still shows no issues, then phenylketonuria can be ruled out. Generally, if phenylketonuria is diagnosed, it should be treated promptly and properly.

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Written by Zeng Hai Jiang

Pediatrics

45sec

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Can phenylketonuria be breastfed?

Once a child with phenylketonuria is diagnosed, natural diets should be ceased and a low-phenylalanine diet treatment should be initiated. Treatment with a low-phenylalanine formula should continue at least until the age of 12. Breast milk is the ideal natural food for infants; therefore, although breastfeeding should be temporarily halted after diagnosis, it should not be completely stopped so that it can be promptly reintroduced once blood phenylalanine levels are controlled. When blood phenylalanine levels are controlled to an ideal concentration, gradually reintroduce small amounts of natural diet, preferably starting with breast milk, as it contains only one-third the phenylalanine content of cow's milk.