Porphyrins, Fractionated, Quantitative, 24‑Hour Urine
Also known as: Heptacarboxyporphyrin, Tetracarboxyporphyrin
Use
Quantitative fractionated porphyrin analysis in a 24‑hour urine collection is used for diagnostic evaluation of porphyrias and related disorders. It assists in characterizing porphyrin excretion patterns across multiple porphyrin species, aiding in differential diagnosis among porphyrias such as porphyria cutanea tarda, acute intermittent porphyria, hereditary coproporphyria, variegate porphyria, and congenital erythropoietic porphyria. It may also support evaluation of elevations due to toxins or medications affecting heme synthesis.
Special Instructions
Requires collection of a full 24‑hour urine specimen, with total volume documented. Specimen must be protected from light and preferably collected with sodium carbonate as preservative. Refrigeration during collection is essential; frozen stability enhances transport. Performing laboratory is Quest Diagnostics Nichols Institute, San Juan Capistrano, CA. Ordering from Quest test code 729 effective March 27, 2023.
Limitations
Specimens exposed to light, not refrigerated, or with low pH (<4.0) may yield inaccurate results or be rejected. Certain porphyrias (e.g., EPP/XLDPP) may not be detected as their protoporphyrin is not excreted in urine. Porphyrin elevations can result from non‑porphyric causes such as drug exposures, toxins, hematologic or hepatobiliary disorders, which may complicate interpretation.
Methodology
Other
Biomarkers
Result Turnaround Time
3-8 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
2 mL aliquot from 24‑hour urine
Minimum Volume
Not provided
Container
24‑hour urine container (amber, light‑protected), with sodium carbonate preservative or no preservative if properly refrigerated and protected from light
Collection Instructions
Collect a full 24‑hour urine specimen; protect from light (amber container or aluminum foil); sodium carbonate preservative preferred; keep refrigerated during collection.
Storage Instructions
Refrigerated during collection; frozen preferred for transport
Causes for Rejection
Specimen received at room temperature; not protected from light; pH less than 4.0
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Unacceptable |
| Refrigerated | 7 days |
| Frozen | 30 days |