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Medical Laboratories

Phenylalanine & Tyrosine PKU Test

Phenylalanine and Tyrosine Quantitative Plasma Test (PKU)

Precise amino acid analysis for early detection of metabolic disorders, ensuring healthy growth and development for infants and children while preventing enzyme deficiency complications.

Trusted medical contentUpdated: 25-04-2026Views: 89LHL-627

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Phenylalanine & Tyrosine PKU Test | Phenylalanine and Tyrosine Quantitative Plasma Test (PKU)

Home Service Available

Service typeLaboratory test (Blood)

Duration10-15 minutes

Fasting / preparation4-8 hours fasting

Home serviceAvailable

Medical notice: this information is for education and service understanding. It is not a diagnosis or a recommendation for an unnecessary procedure.

About this service

Phenylalanine and Tyrosine quantitative analysis in plasma (Phenylalanine and Tyrosine, Quantitative, Plasma - PKU) is an important medical test aimed at measuring the levels of the amino acids phenylalanine and tyrosine in the blood. This test is primarily used to diagnose phenylketonuria (PKU), a genetic disorder that affects the body’s ability to metabolize phenylalanine, which can lead to its accumulation in the body and cause serious health problems if not managed. It is recommended to perform this test early in life, usually as part of newborn screening, to monitor amino acid levels and determine the need for dietary or therapeutic interventions. The results help doctors make informed decisions regarding management of the condition and ensure the patient’s long-term health.

Purpose Test

Diagnosing Phenylketonuria (PKU): This is one of the main tests used to diagnose Phenylketonuria (PKU), a genetic disorder caused by a deficiency in the enzyme phenylalanine hydroxylase. This condition prevents the body from converting phenylalanine into tyrosine, leading to the accumulation of phenylalanine in the blood and causing brain damage if untreated.
This is one of the main tests used to diagnose Phenylketonuria (PKU), a genetic disorder caused by a deficiency in the enzyme phenylalanine hydroxylase. This condition prevents the body from converting phenylalanine into tyrosine, leading to the accumulation of phenylalanine in the blood and causing brain damage if untreated.
Assessing Metabolic Disorders: The test can help identify metabolic issues related to amino acids, such as phenylalanine and tyrosine metabolism, which is important for diagnosing disorders that affect amino acid metabolism.
The test can help identify metabolic issues related to amino acids, such as phenylalanine and tyrosine metabolism, which is important for diagnosing disorders that affect amino acid metabolism.
Monitoring Treatment Effectiveness: After diagnosing PKU, this test is used to track the patient's response to dietary treatment or medications, such as a phenylalanine-restricted diet or medications that lower phenylalanine levels in the blood.
After diagnosing PKU, this test is used to track the patient's response to dietary treatment or medications, such as a phenylalanine-restricted diet or medications that lower phenylalanine levels in the blood.
Determining the Need for Dietary Interventions: The test helps in determining if the patient's diet needs adjustment to control the levels of phenylalanine and tyrosine in the body, ensuring healthy development and growth.
The test helps in determining if the patient's diet needs adjustment to control the levels of phenylalanine and tyrosine in the body, ensuring healthy development and growth.

Recommended groups

As part of the Phenylketonuria (PKU) screening program in newborn screening tests. Early detection of PKU is essential to prevent developmental and neurological issues.
Those with a family history of Phenylketonuria (PKU) or other similar metabolic disorders. Genetic predisposition increases the likelihood of inheriting the condition.
Children who exhibit symptoms such as growth delays or learning problems, as these can indicate metabolic disorders, including PKU. Early diagnosis and treatment can help prevent long-term developmental delays.
Women with a history of PKU need this test to monitor amino acid levels during pregnancy. Ensuring appropriate levels of phenylalanine is crucial for fetal health, as high levels can negatively impact the baby's development.
Timely testing helps in early diagnosis and quick intervention, which significantly improves health outcomes by enabling better management of metabolic disorders such as PKU.

Symptoms indicative

Difficulties in physical or mental development, such as failure to thrive or poor cognitive milestones.
Changes in behavior, including emotional outbursts, irritability, or aggression.
Problems with concentration, learning, or academic performance, which could point to metabolic disorders affecting brain function.
The occurrence of unexplained seizures, which could be a sign of neurological problems linked to metabolic imbalances.
A distinct odor similar to "musty" or "mousy" (resembling musk), often noticeable in the child’s sweat or urine, which can indicate elevated phenylalanine levels.
Difficulty with feeding or maintaining a healthy weight due to metabolic disturbances.

Normal Levels

Adults: 0.5 - 1.5 mg/dL (30 - 90 µmol/L)
Newborns: 1.0 - 6.0 mg/dL (60 - 360 µmol/L)
Adults: 0.5 - 1.5 mg/dL (30 - 90 µmol/L)
Newborns: 1.0 - 4.0 mg/dL (60 - 240 µmol/L)

What is included?

✓Phenylalanine and Tyrosine, Quantitative, Plasma - PKU Test
✓The optimal health guidance based on the result.
✓Personal support services from Lahalak

Conditions and notices

4-8 hours fasting
The terms and conditions announced on the "Lahalak" medical platform apply.
There are no special conditions for the service other than those mentioned.

Frequently Asked Questions

Short answers to the FAQs published with this service.

What is the purpose of this test?

This test is used to diagnose Phenylketonuria (PKU) and monitor amino acid levels in the blood. Elevated levels of phenylalanine can indicate PKU, a genetic metabolic disorder.

How is the test performed?

A blood sample is drawn from a vein, usually in the arm. The procedure is quick and minimally invasive.

Does the test require fasting?

In some cases, fasting may be required before the test. It's important to follow the instructions given by your healthcare provider prior to the test.

How long does it take to get the results?

Results are typically available within a few days, though this may vary depending on the laboratory.

What do elevated or low results mean?

Elevated phenylalanine levels may indicate Phenylketonuria (PKU) or other metabolic disorders. Low phenylalanine levels may suggest other metabolic imbalances or conditions.

Are there any risks associated with the test?

The test is generally safe, but there may be some minor discomfort or bruising at the site where the blood is drawn.

What should I do if the results are abnormal?

If the test results are abnormal, you should consult your doctor for further testing or treatment options, which may include dietary changes or medications to manage amino acid levels.

Service resources and references

References and additional resources

Reference material and files associated with this service when available.

Scientific references

Smith, A., & Colleagues. (2003). Simultaneous measurement of phenylalanine and tyrosine in phenylketonuric plasma and dried blood by high‑performance liquid chromatography. Journal of Chromatography B.
Johnson, B., & Associates. (2009). Determination of phenylalanine and tyrosine in plasma and dried blood samples using HPLC with fluorescence detection. Clinical Chemistry.
Lee, C., & Team. (2015). Determination of Phenylalanine and Tyrosine by high performance liquid chromatography‑tandem mass spectrometry for PKU diagnosis and monitoring. Journal of Mass Spectrometry Methods.
Anderson, D., & Colleagues. (1998). Use of phenylalanine‑to‑tyrosine ratio determined by tandem mass spectrometry to improve newborn screening for phenylketonuria. Clinical Chemistry.

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Important Notice:

Content on LahaLak is provided for educational purposes only. It is not a medical diagnosis, prescription, or substitute for consulting a qualified clinician. Medical decisions should not be made from this content alone.

Content reviewed according to the LahaLak Quality Charter.Editorial Policy & Medical Standards

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Medical Laboratories

Phenylalanine & Tyrosine PKU Test

Phenylalanine and Tyrosine Quantitative Plasma Test (PKU)

Precise amino acid analysis for early detection of metabolic disorders, ensuring healthy growth and development for infants and children while preventing enzyme deficiency complications.

Trusted medical contentUpdated: 25-04-2026Views: 89LHL-627

View service availability

Home Service Available

Service typeLaboratory test (Blood)

Duration10-15 minutes

Fasting / preparation4-8 hours fasting

Home serviceAvailable

Medical notice: this information is for education and service understanding. It is not a diagnosis or a recommendation for an unnecessary procedure.

About this service

Purpose Test

Diagnosing Phenylketonuria (PKU): This is one of the main tests used to diagnose Phenylketonuria (PKU), a genetic disorder caused by a deficiency in the enzyme phenylalanine hydroxylase. This condition prevents the body from converting phenylalanine into tyrosine, leading to the accumulation of phenylalanine in the blood and causing brain damage if untreated.
This is one of the main tests used to diagnose Phenylketonuria (PKU), a genetic disorder caused by a deficiency in the enzyme phenylalanine hydroxylase. This condition prevents the body from converting phenylalanine into tyrosine, leading to the accumulation of phenylalanine in the blood and causing brain damage if untreated.
Assessing Metabolic Disorders: The test can help identify metabolic issues related to amino acids, such as phenylalanine and tyrosine metabolism, which is important for diagnosing disorders that affect amino acid metabolism.
The test can help identify metabolic issues related to amino acids, such as phenylalanine and tyrosine metabolism, which is important for diagnosing disorders that affect amino acid metabolism.
Monitoring Treatment Effectiveness: After diagnosing PKU, this test is used to track the patient's response to dietary treatment or medications, such as a phenylalanine-restricted diet or medications that lower phenylalanine levels in the blood.
After diagnosing PKU, this test is used to track the patient's response to dietary treatment or medications, such as a phenylalanine-restricted diet or medications that lower phenylalanine levels in the blood.
Determining the Need for Dietary Interventions: The test helps in determining if the patient's diet needs adjustment to control the levels of phenylalanine and tyrosine in the body, ensuring healthy development and growth.
The test helps in determining if the patient's diet needs adjustment to control the levels of phenylalanine and tyrosine in the body, ensuring healthy development and growth.

Recommended groups

As part of the Phenylketonuria (PKU) screening program in newborn screening tests. Early detection of PKU is essential to prevent developmental and neurological issues.
Those with a family history of Phenylketonuria (PKU) or other similar metabolic disorders. Genetic predisposition increases the likelihood of inheriting the condition.
Children who exhibit symptoms such as growth delays or learning problems, as these can indicate metabolic disorders, including PKU. Early diagnosis and treatment can help prevent long-term developmental delays.
Women with a history of PKU need this test to monitor amino acid levels during pregnancy. Ensuring appropriate levels of phenylalanine is crucial for fetal health, as high levels can negatively impact the baby's development.
Timely testing helps in early diagnosis and quick intervention, which significantly improves health outcomes by enabling better management of metabolic disorders such as PKU.

Symptoms indicative

Difficulties in physical or mental development, such as failure to thrive or poor cognitive milestones.
Changes in behavior, including emotional outbursts, irritability, or aggression.
Problems with concentration, learning, or academic performance, which could point to metabolic disorders affecting brain function.
The occurrence of unexplained seizures, which could be a sign of neurological problems linked to metabolic imbalances.
A distinct odor similar to "musty" or "mousy" (resembling musk), often noticeable in the child’s sweat or urine, which can indicate elevated phenylalanine levels.
Difficulty with feeding or maintaining a healthy weight due to metabolic disturbances.

Normal Levels

Adults: 0.5 - 1.5 mg/dL (30 - 90 µmol/L)
Newborns: 1.0 - 6.0 mg/dL (60 - 360 µmol/L)
Adults: 0.5 - 1.5 mg/dL (30 - 90 µmol/L)
Newborns: 1.0 - 4.0 mg/dL (60 - 240 µmol/L)

What is included?

✓Phenylalanine and Tyrosine, Quantitative, Plasma - PKU Test
✓The optimal health guidance based on the result.
✓Personal support services from Lahalak

Conditions and notices

4-8 hours fasting
The terms and conditions announced on the "Lahalak" medical platform apply.
There are no special conditions for the service other than those mentioned.

Frequently Asked Questions

Short answers to the FAQs published with this service.

What is the purpose of this test?

This test is used to diagnose Phenylketonuria (PKU) and monitor amino acid levels in the blood. Elevated levels of phenylalanine can indicate PKU, a genetic metabolic disorder.

How is the test performed?

A blood sample is drawn from a vein, usually in the arm. The procedure is quick and minimally invasive.

Does the test require fasting?

In some cases, fasting may be required before the test. It's important to follow the instructions given by your healthcare provider prior to the test.

How long does it take to get the results?

Results are typically available within a few days, though this may vary depending on the laboratory.

What do elevated or low results mean?

Elevated phenylalanine levels may indicate Phenylketonuria (PKU) or other metabolic disorders. Low phenylalanine levels may suggest other metabolic imbalances or conditions.

Are there any risks associated with the test?

The test is generally safe, but there may be some minor discomfort or bruising at the site where the blood is drawn.

What should I do if the results are abnormal?

If the test results are abnormal, you should consult your doctor for further testing or treatment options, which may include dietary changes or medications to manage amino acid levels.

Service resources and references

References and additional resources

Reference material and files associated with this service when available.

Scientific references

Smith, A., & Colleagues. (2003). Simultaneous measurement of phenylalanine and tyrosine in phenylketonuric plasma and dried blood by high‑performance liquid chromatography. Journal of Chromatography B.
Johnson, B., & Associates. (2009). Determination of phenylalanine and tyrosine in plasma and dried blood samples using HPLC with fluorescence detection. Clinical Chemistry.
Lee, C., & Team. (2015). Determination of Phenylalanine and Tyrosine by high performance liquid chromatography‑tandem mass spectrometry for PKU diagnosis and monitoring. Journal of Mass Spectrometry Methods.
Anderson, D., & Colleagues. (1998). Use of phenylalanine‑to‑tyrosine ratio determined by tandem mass spectrometry to improve newborn screening for phenylketonuria. Clinical Chemistry.

Service availability

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Labeeb & Search Tools

Let us help you

Use Labeeb smart tools to understand reports related to (Medical Laboratories), or search the platform directory directly.

Browse services alphabetically A-Z

LahaLak is here to help

Didn’t find the service?

We can help request the service and prepare your inquiry, or you can ask Labeeb to guide you to the most suitable category or service.

Phone call

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Important Notice:

Content reviewed according to the LahaLak Quality Charter.Editorial Policy & Medical Standards

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