Porphyrins, Fractionated, Quantitative and Porphobilinogen, 24‑Hour Urine
Use
Measurement of fractionated porphyrins and porphobilinogen (PBG) in a 24‑hour urine sample is useful for evaluation and differentiation of porphyrias such as acute intermittent porphyria, hereditary coproporphyria, variegate porphyria, congenital erythropoietic porphyria, and porphyria cutanea tarda. Altered excretion patterns of porphyrins and PBG aid in diagnosis and guide further testing. Quest Diagnostics provides this combined analysis in one orderable test code 17198.
Special Instructions
Specimen must be light‑protected during collection (e.g., amber container or wrapped in aluminum foil). Adding sodium carbonate (5 g per 100 mL urine) as a preservative is preferred but not required. Urine should be refrigerated during collection and frozen or protected after completion prior to shipment. Based on internal record, this test code became effective March 27, 2023, with performance at Quest Diagnostics Nichols Institute, San Juan Capistrano.
Limitations
Porphyrins and PBG are sensitive to degradation from ultraviolet light, low pH, or elevated temperatures. False‑negatives may occur if collected when patient is asymptomatic or specimen exposure to light occurs. Protoporphyrin is not detected in urine, requiring plasma or fecal testing for some porphyrias. Medications, toxins, and hepatic or hematologic disorders may affect porphyrin profiles and must be considered. Interpretation should follow appropriate porphyria diagnostic algorithms.
Methodology
Other
Biomarkers
Result Turnaround Time
3-8 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
Not provided
Minimum Volume
Not provided
Container
Amber or light‑protected container
Collection Instructions
Collect 24‑hour urine; protect from light by amber container or wrapping in aluminum foil; refrigerate during collection; add sodium carbonate preservative preferred.
Storage Instructions
Keep refrigerated during collection; freeze after completion or keep protected from light.
Other tests from different labs that may be relevant