Metabolic Disorders Inborn errors of amino acid metabolism
Phenylketonuria (PKU)
Rare Disease Classifications:
IMPORTANT INFORMATION
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Contributors
This page has been co-developed with RVA Partner Metabolic Dietary Disorders Association1, and the Australian Society for Inborn Errors of Metabolism.2
Quick Page Search:
Emergency Management | Clinical Care Guidelines | Synonyms | Summary | Personal Stories | Symptoms | Cause/Inheritance | Diagnosis | Treatment | Clinical Care | Research and Data | Rare Disease Organisation(s) | Support Services/Resources | Mental Health | Other | References
Emergency Management
There may be special considerations for the emergency management of individuals living with PKU presenting to emergency departments.
Clinical Care Guidelines
Synonyms
Phenylalanine Hydroxylase Deficiency; Oligophrenia Phenylpyruvica; Folling Disease, Hyperphenylalaninemia
Summary
Phenylketonuria (PKU) is a genetic metabolic disorder in which phenylalanine (phe) is unable to be metabolised. Phe is one of the building blocks (amino acids) of proteins. Humans cannot make phe, but it is a natural part of the foods we eat.3 However, people do not need all the phe they eat, so the body converts extra phe to another harmless amino acid, tyrosine. People with PKU cannot properly break down the extra phe to convert it to tyrosine. This means phe builds up in the person’s blood, urine, and body. If PKU is not treated, phe can build up to harmful levels in the body and this can affect many body systems including the brain and nervous system.3-6
PKU varies from mild to severe. The most severe form is known as classic PKU. Without treatment, children with classic PKU develop permanent intellectual disability. Light skin and hair, seizures, developmental delays, behavioural problems, and psychiatric disorders are also common. Less severe forms, sometimes called “mild PKU”, “variant PKU” and “non-PKU hyperphenylalaninemia”, have a smaller risk of intellectual disability and brain damage. Mothers who have PKU and no longer follow a phenylalanine-restricted diet have an increased risk of having children with an intellectual disability, because their babies may be exposed to very high levels of phe before birth.3-6
Malignant PKU is another type of PKU caused by the deficiency of a cofactor that helps metabolism of phe. This condition is also identified via newborn blood spot screening through elevated phe and requires further tests to confirm deficiency of the cofactor. Malignant PKU is not responsive to diet; however, it is treatable with medication.
Symptoms
Early diagnosis and treatment of PKU ensures that babies grow and develop in a similar way to their healthy peers who don’t have PKU. However, if not diagnosed and treated early, high levels of phe in the blood from PKU can cause developmental delays noticeable in the very first year of life, neurological complications including intellectual disability, hyperactivity and poor coordination, aggressive behaviour or emotional disturbances including anxiety, and, if left untreated, severe brain damage.3
Please speak to your medical team to learn more about the symptoms and complications of PKU.
Cause/Inheritance
PKU is an autosomal recessive inherited disorder caused by the genetic mutation of the gene responsible for ensuring the body produces the enzyme phenylalanine hydroxylase (PAH) which breaks down phe. For a child to inherit PKU, both parents must carry at least one copy of the faulty gene.2
If you would like to learn more about the inheritance and impact of this condition, please ask your doctor for a referral to a genetic counsellor. Genetic counsellors are qualified allied health professionals who can provide information and support regarding genetic conditions and testing. More information on genetic counselling can be found on the National Services page and specific State and Territory Services pages on the RARE Portal.
Diagnosis
In Australia and New Zealand, PKU is usually diagnosed via the Newborn Bloodspot Screening (NBS) Program. After parental consent, a nurse or midwife will collect the baby’s blood via a heel prick blood test and send it to a laboratory to test for several rare genetic conditions, including PKU. PKU is detected by measuring phe levels, which begin to rise immediately after birth in affected babies. If phe levels are found to be high, doctors will request more tests to confirm a diagnosis of PKU. Immediately after diagnosis, the baby is referred to a metabolic clinical service where they are prescribed a special formula to maintain safe levels of phe in the blood. It is critical that PKU is detected early via the NBS Program and managed immediately after diagnosis to prevent long term damage.3
Treatment
Treatment consists of a life-long strict low-protein diet. The level of protein intake from foods is based on the extent of the individual’s phe tolerance. To meet protein requirements, phe-free or low phe supplements need to be taken, which are also enriched with micronutrients to prevent malnutrition. Strict compliance with diet and maintaining phe concentrations within the recommended reference ranges ensures normal development and life expectancy. When PKU is diagnosed early and treated with diet and supplementation, children can reach their full potential.2
According to The PKU Handbook prepared by the Australasian Society for Inborn Errors of Metabolism (ASIEM), treatment for most people with PKU in Australia and New Zealand, is a low-protein diet and a special nutritional supplement, together with regular blood tests to measure the phe level and regular attendance at a metabolic clinic.2
Some people with PKU may benefit from a medication containing sapropterin (BH4), which is an enzyme cofactor. For more information, please refer to The PKU Handbook.2
It is best to speak with your medical team to learn more about the most suitable treatment for your child.
Clinical Care
Children’s Clinical Services
| States/Territories | Clinical Services |
|---|---|
| New South Wales /
Australian Capital Territory |
The Children’s Hospital at Westmead Corner Hawkesbury Rd & Hainsworth St Westmead NSW 2145 Ph: 02 9845 2525 |
| The Sydney Children’s Hospitals Network Sydney Children’s Hospital Randwick High Street, Randwick 2031 Ph: 02 93825608 Email: [email protected] |
|
| Queensland | Queensland Lifespan Metabolic Medicine Service The Metabolic Medicine clinic Level 6 (6c), Queensland Children’s Hospital, South Brisbane 4101 |
| Victoria/Tasmania | Specialist Clinic D First Floor East Building Royal Children’s Hospital 50 Flemington Rd Parkville VIC 3052 Ph: 03 93453909 |
| Western Australia | Clinic B Perth Children’s Hospital 15 Hospital Avenue Nedlands WA 6009 Ph: 08 6456 5298 Emergency Clinical Call Number: Ph: 08 6456 2222 Ask for the metabolic doctor on call. |
| South Australia /
Northern Territory |
Children’s Outpatient Area Level 1 Rogerson Building Women’s and Children’s Hospital 72 King Williams St North Adelaide SA 5006 Ph: 08 8161 7295 Emergency Clinical Call Number: Ph: 08 8161 7290 |
Adult Clinical Services
| States/Territories | Clinical Services |
|---|---|
| New South Wales /
Australian Capital Territory |
Westmead Hospital Hawkesbury Rd & Darcy Rd Westmead NSW 2145 Ph: 02 8890 9780 Email: [email protected] Fax: 02 8890 9789 Emergency Clinical Call Number: Ph: 02 8890 5555 |
| Queensland | Queensland Lifespan Metabolic Medicine Service Adult Metabolic Medicine Clinic Queensland Diabetes and Endocrine Clinic, Master Adult Hospital Ph: 07 3068 2880 Fax: 07 3068 4079 Non-urgent Enquiries and Prescriptions: Ph: 07 3068 4426 Email: [email protected] Emergency Clinical Call Number: Ph: 07 3068 4426 – Business hours Ph: 07 3068 1111 – After hours. Ask for the metabolic doctor on call. |
| Victoria/Tasmania | Metabolic Diseases Unit Royal Melbourne Hospital Grattan St Parkville VIC 3052 Ph: 03 9342 7074 Emergency Clinical Call Number: Ph: 03 9342 7000 Ask for the metabolic doctor on call. |
| Western Australia | Outpatients Clinic Level 3, 196 Goderich St, Wellington Street Campus Royal Perth Hospital Perth WA 6000 Ph: 6477 5213 Fax: 6477 5238 |
| South Australia /
Northern Territory |
Endocrine & Metabolic Unit Level 8 Outpatient block Royal Adelaide Hospital, North Terrace Adelaide SA 5000 Outpatient Call Centre & Referral Management Hub Ph: 1300 153 853 Fax: (08) 7074 6247 Emergency Clinical Call Number: Ph: 08 7074 0000 Ask for the Endocrine Registrar on-call. |
Research and Data
For clinical trials and research updates please visit the MDDA website.1
Please visit Australian Clinical Trials to learn about clinical trials for PKU in Australia; there may not be any clinical trials currently available.
Information regarding clinical trials for PKU in other countries can be found at ClinicalTrials.gov; there may not be any clinical trials currently available.
It is best to discuss your interest in any clinical trials with your medical team to determine suitability and eligibility.
Rare Disease Organisation(s)
Metabolic Dietary Disorders Association (MDDA) RVA Partner Australian Organisation
Website: https://mdda.org.au/
Phone: (03) 9723 0600
Freecall: 1800 288 460
Email: [email protected]
Please note that RVA does not necessarily monitor or endorse each group/organisation’s operational governance.
Support Services/Resources
- MDDA Patient Pathways Telehealth Nurse
- Carer’s Allowance – parents of babies with PKU are automatically eligible for this
- The Inborn Errors of Metabolism Allowance claim form
Please visit the National and State Services pages for general social services.
Mental Health
Please visit the ‘Mental Health’ sections listed on the National and State Services pages.
Other
Further information on PKU can be found at:
For more resources on diet and nutrition, exercise, education, preparing for school or childcare, financial support, dental care, and obstetric care please see The PKU Handbook.2
References
- Metabolic and Dietary Disorders Association. https://www.mdda.org.au/
- Australian Society for Inborn Errors of Metabolism. The PKU Handbook 2005 [Edited 2020] 133 p. https://www.hgsa.org.au/common/Uploaded%20files/pdfs/asiem%20dietary%20handbooks/PKU.pdf
- Genetic and Rare Diseases (GARD) Information Center. Phenylketonuria. Accessed 15 October 2021. https://rarediseases.info.nih.gov/diseases/7383/phenylketonuria
- Regier DS, Greene CL. GeneReviews [Internet]. University of Washington, Seattle (WA). Phenylalanine Hydroxylase Deficiency 2017Jan; http://www.ncbi.nlm.nih.gov/books/NBK1504/.
- Bodamer OA. Overview of phenylketonuria. 2016 21; https://www.uptodate.com/contents/overview-of-phenylketonuria.
- Rush ET. Phenylketonuria (PKU). Medscape Reference. May 31, 2018; https://emedicine.medscape.com/article/947781-overview.
Page Last Updated
30/01/2023 09:37
