Unidentified substance concentration in serum/plasma (24-hour urine collection)
This test measures the amount of an unknown substance in your blood or urine over a 24-hour period. Results may help identify metabolic, toxicological, or other underlying conditions.
["This test helps doctors track specific substances that may require further investigation."]
Key facts at a glance
- LOINC
- 31693-5
- Short code
- ENA Unident Ab Ser Ql
- Synonyms
- ENA Unident Ab Ser Ql
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What This Test Measures
The test detects the presence and concentration of an unidentified substance in your serum or plasma, collected over a 24-hour period. This may include organic acids, amino acids, drugs, toxins, or other metabolites depending on clinical context. Since the substance is not specified, results are interpreted by healthcare providers in relation to patient symptoms, medical history, and other lab findings.
Why It’s Ordered
Your doctor may order this test if they suspect an abnormal substance is affecting your body, such as in cases of suspected poisoning, metabolic disorders, or drug monitoring. It could also be part of a broader evaluation for unexplained symptoms like fatigue, neurological issues, or organ dysfunction.
Sample Collection Process
A 24-hour urine sample is typically collected by collecting all urine voided over a full day, usually from midnight to midnight. Blood may be drawn separately for serum/plasma testing. Proper collection instructions are provided to ensure accuracy.
Preparation and Restrictions
Follow your healthcare provider’s instructions carefully. Avoid certain medications, foods, or fluids that could interfere with test results. Some substances may require fasting or specific dietary restrictions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Results from this test can reveal hidden health issues, such as toxic exposures, genetic metabolic disorders, or abnormal metabolic pathways. Elevated or unusual levels may prompt additional testing or treatments. Interpretation depends on clinical context, including symptoms, medical history, and other diagnostic findings.
Frequently asked questions
What Does a Positive or Abnormal Result Mean?
How Long Does It Take to Get Results?
Can I Fast Before This Test?
Sources
- 1
- 2Lab Tests OnlineSource
- 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