Porphyrins, Quantitative, 24-Hour Urine
Also known as: Coproporphyrin, Uroporphyrin
Use
Evaluate porphyrias, including those involving deficiencies of enzymes that are needed for heme synthesis and chemical porphyrias.
Special Instructions
Ensure 24-hour urine collection volume is accurately noted on the test request form. Proper specimen handling includes protecting from light and refrigeration during transport.
Limitations
Increased porphobilinogen can be present in patients using oral contraceptives, potentially affecting results. This test, along with δ-aminolevulinic acid, might not detect protoporphyria. Coproporphyrinuria lacks sensitivity and specificity for detecting lead poisoning. Erythrocyte uroporphyrinogen-1-synthase activity decrease is associated with latent acute intermittent porphyria and is not detectable with this test. The test might miss some cases of latent acute intermittent porphyria compared to red cell uroporphyrinogen-1-synthase activity measurement.
Methodology
Other
Biomarkers
LOINC Codes
- 43116-3
- 47253-0
- 6877-5
- 47254-8
- 6878-3
- 11228-4
- 3113-8
- 2407-5
- 24462-4
- 27400-1
- 9527-3
- 11221-9
- 9730-3
Result Turnaround Time
3-7 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
2-mL aliquot
Minimum Volume
1.5-mL aliquot
Container
12-mL plastic transport tube without preservative
Collection Instructions
Instruct patient to void at 8 AM (or 8 PM) and discard the specimen. Then collect all the urine including the final specimen voided at the end of the 24-hour collection period (8 AM [or 8 PM] the following day). Mix well. Measure, record total urine volume on the test request form, along with the patient's name, date, and time collection started and finished. Transfer required aliquot into a LabCorp amber plastic transport tube with amber cap (LabCorp N° 23598). If unavailable, cover transport tube completely, top and bottom, with aluminum foil. Identify specimen with patient's name directly on the amber transport tube and on the outside of the aluminum foil. Secure with tape. Specimen must be kept refrigerated during transport.
Storage Instructions
Refrigerate and protect from light.
Causes for Rejection
Stored specimen not refrigerated; specimen exposed to light; acid preservative; pH <3
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Unstable |
| Refrigerated | 7 days |
| Frozen | 14 days |