Porphobilinogen, quantitative, 24-hour urine
Porphobilinogen, quantitative, 24-hour urine-994
Quantitative porphobilinogen, 24-hour urine
Porphobilinogen levels in the urine should be measured during acute attacks of abdominal pain, extremity pain or paresthesias, tachycardia, nausea and vomiting, neurologic abnormalities, and to investigate dark urine.
It is an initial test for acute intermittent porphyria, which is characterized by urinary excretion of porphobilinogen and δ-aminolevulinic acid during acute attacks. Increased urinary excretion of porphobilinogen may be caused also by acute attacks of variegate porphyria or of hereditary coproporphyria, and also in lead poisoning (rarely). In lead poisoning, urinary δ-aminolevulinic acid measurement is more useful.
How to collect a 24 hr urine sample
Specimen must be kept refrigerated during collection
- Measure and record the 24-hour total volume
- Mix well
- Transfer the urine aliquot into a Amber screw-cap polypropylene frozen transport tube/vial - 4mL (LabCorp)
- Label with the patient's name, date, and time collection started and finished
- The specimen should be frozen immediately and maintained frozen until tested
Protect from light
- Total volume
Frozen (preferred) - 1 month
Refrigerated - 24 hours
- Specimen not refrigerated during collection
- Specimen not protected from light
- Specimen not a 24-hour collection
- Specimen not frozen
Ion-exchange chromatography/spectrophotometry
Porphobilinogen,Qn,U: 0.0 − 2.0 mg/L
Porphobilinogen, 24U: 0.0 − 1.5 mg/24 hr