Understanding Your Blood Test: What to Expect and What Your Results Mean
This test checks for the presence of 4-hydroxyphenyllactate in your urine, a substance that may indicate certain metabolic disorders.
{"4-Hydroxyphenyllactate is a byproduct of tyrosine metabolism","This test helps diagnose hereditary tyrosinemia and liver diseases","A positive result means the substance was detected in your urine","The test uses a urine sample collected during your visit","Follow your doctor's instructions for preparation"}
Key facts at a glance
- LOINC
- 29870-3
- Short code
- 4-HPLA
- Synonyms
- 4OH-phenyllactate Ur Ql
- Category
- chemistry
- Sample
- urine
- Container
- Sterile urine collection container (plastic or glass)
- Units
- N/A
- Critical range
- — – 4 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Gas Chromatography-Mass Spectrometry (GC-MS) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 82131
- SNOMED
- 314217002
- Specimen volume
- 10-50 mL preferred
- Stability
- Refrigerate at 2-8°C if not processed within 24 hours; freeze at -20°C or below for longer storage
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 48–168 hours
- Order
- routine
What is this test? This test is a laboratory analysis that measures specific substances in a sample of your blood. It helps your doctor evaluate your overall health, screen for certain conditions, and monitor how well a treatment is working over time.
The urine 4-hydroxyphenyllactate test is a diagnostic test that detects whether 4-hydroxyphenyllactate is present in your urine. 4-Hydroxyphenyllactate is a metabolic byproduct produced when your body breaks down the amino acid tyrosine. Under normal conditions, your body processes tyrosine efficiently, and only small amounts of 4-hydroxyphenyllactate are excreted in urine.
How is the test performed? A trained healthcare professional will clean your skin, wrap a band around your upper arm, and draw a small sample of blood from a vein, usually in your inner elbow. The sample is then sent to a laboratory, and the entire procedure usually takes only a few minutes.
A urine sample is collected during your appointment, typically in a clean container provided by the laboratory. The sample is then analyzed using laboratory techniques to detect the presence or absence of 4-hydroxyphenyllactate. No special preparation such as fasting is usually required, but you should follow any specific instructions given by your healthcare provider.
What do the results mean? Your results are compared with standard reference ranges. Values within the normal range are generally reassuring, while higher or lower values may point to an infection, a nutritional deficiency, or another condition that your doctor will assess together with your symptoms and medical history.
The test result is reported as 'Positive' or 'Negative' (or 'Present'/'Not Present'). A positive result indicates that 4-hydroxyphenyllactate was detected in your urine, which may suggest abnormal tyrosine metabolism. Your healthcare provider will interpret these results in conjunction with your clinical symptoms, medical history, and other test results to determine the cause and appropriate follow-up.
Are there any risks? This test is very safe. You may feel a brief sting when the needle is inserted, and mild bruising, soreness, or slight bleeding at the puncture site can occur. Serious complications such as infection are rare, and most people can return to their normal activities right away.
This test involves only a standard urine collection, which is generally safe and carries minimal risks. Some patients may experience minor discomfort when providing a urine sample. If you have concerns about the test procedure, please discuss them with your healthcare provider.
Reference range
Not DetectedN/A
Collect random urine specimen in clean, sterile container. No special preparation required. Inform laboratory of any medications or supplements being taken as they may affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The presence of 4-hydroxyphenyllactate in urine is primarily associated with hereditary tyrosinemia type I, a rare genetic disorder affecting tyrosine metabolism. In this condition, deficiency of the enzyme fumarylacetoacetate hydrolase leads to accumulation of tyrosine metabolites including 4-hydroxyphenyllactate, which are excreted in urine. Elevated levels may also be observed in liver diseases, certain metabolic disorders, or as a result of exposure to certain medications or toxins. This test helps healthcare providers screen for and monitor these conditions.
Frequently asked questions
Why do I need this test?
Do I need to fast before the test?
What happens if my result is positive?
Is this test only for children?
How long does it take to get results?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy