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Porphobilinogen, Quantitative, 24-Hour Urine
MessageFor Specimen Integrity during Extreme Weather see the “Lockbox Usage in Extreme Weather” document at the top of this page.
Test Code
PORPBN
CPT Codes
84110
Includes
CPT code 81050 may be added at an additional charge for volume measurement
Preferred Specimen
2 mL from 24-hour urine containing sodium carbonate collected in a plastic leak-proof container - protect from light
Minimum Volume
1 mL
Instructions
24-hour urine, collection should be adjusted to a pH of 6-7 with 5g sodium carbonate (Na2CO3). Add the sodium carbonate at the start of the collection. The urine should be refrigerated and protected from light during collection.
Whenever possible, the specimen should be collected during an acute episode because porphobilingen (PBG) may decrease rapidly upon remission. PBG may also degrade when samples are exposed to UV light for extended periods, or are transported at ambient temperature. If an amber collection jug/urine cup is not available, the sample must be protected from light by completely wrapping the container in aluminum foil. Twenty-four hour specimens should be refrigerated and protected from UV light during collection. PBG is most stable at pH 6-7, but samples may be sent with or without preservative. All results should be interpreted in the context of clinical findings, relevant history, and other laboratory data.
Whenever possible, the specimen should be collected during an acute episode because porphobilingen (PBG) may decrease rapidly upon remission. PBG may also degrade when samples are exposed to UV light for extended periods, or are transported at ambient temperature. If an amber collection jug/urine cup is not available, the sample must be protected from light by completely wrapping the container in aluminum foil. Twenty-four hour specimens should be refrigerated and protected from UV light during collection. PBG is most stable at pH 6-7, but samples may be sent with or without preservative. All results should be interpreted in the context of clinical findings, relevant history, and other laboratory data.
Transport Temperature
Refrigerated (cold packs)
Specimen Stability
Room temperature: Unacceptable
Refrigerated: 7 days
Frozen: 30 days
Refrigerated: 7 days
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Not protected from light
Methodology
Chromatography/Mass Spectrometry
FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the U.S. Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
Setup Schedule
Set up: Tues, Thurs, Sat; Report available: 4-7 days
Reference Range
| ≤17 Years | Not established |
| ≥18 Years | <0.34 mg/24 h |
Clinical Significance
Urinary Porphobilinogen is the first step in the diagnosis of acute porphyrias such as acute intermittent porphyria (AIP). AIP is an autosomal dominant disorder characterized by deficiency of porphobilinogen deaminase. An acute attack usually includes gatrointestinal disturbance and neuropsychiatric disorders.
Performing Laboratory
| Quest Diagnostics Nichols Institute-San Juan Capistrano, CA |
| 33608 Ortega Highway |
| San Juan Capistrano, CA 92675-2042 |
Last Updated: December 6, 2021
