Porphobilinogen Screen, Urine

Diagnostic Use

Clinical suspicion of acute porphyria.
May include otherwise unexplained abdominal pain, neurological or psychotic features, skin lesions.

In some cases, it may be an appropriate test for latent acute intermittent porphyria (AIP).

Department

Lipids/Trace Metals

Delphic Registration Code

PORU

Laboratory Handling

Registration

Urine protected from light to Trace metals fridge

Synonyms

PBG (Screen)

Turnaround Time

2 weeks

Test Code

3275

Specimen Type

• Urine

Specimen Requirements

Tube/Container Type:

Preferred

• Pottle

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• Pottle

Preferred Sample Volume (ml)

5

Additional Specimen Information

Pottle of urine, protected from light. (Foil or brown bag)

Aliquot Instructions

Sample Type

• Urine

Minimum Volume (ml)

5

Transport to Lab

Chilled (2 - 8 degrees Celsius)
If overnight - Chilled (2 - 8 degrees Celsius)

Additional Referral/Aliquot Information

5 mL urine Light protected. Fridge

Interpretation

A raised urine PBG is the diagnostic hallmark of an acute attack of porphyria.
A negative urine PBG during an acute symptomatic episode excludes acute porphyria as the cause.

For raised urine PBG, the differential diagnosis is acute intermittent porphyria (AIP), variegate porphyria (VP) or hereditary coproporphyria (HCP). Definitive characterisation requires a full set of samples – blood, urine and faeces protected from the light for porphyrin quantitation and further studies, including HPLC profiling, fluorescence scanning and genotyping as appropriate.

Normal urine PBG does not exclude a non-acute porphyria such as porphyria cutanea tarda (PCT) or erythropoietic protoporphyria (EPP). For evaluation of these disorders, a full set of samples – blood, urine and faeces protected from light is required.

Reference Intervals

Negative (screening test)

If screening test positive, quantitation is undertaken to confirm.

Test Method

Extraction, colour reaction

Non-Funded Test Cost

$37.8 (Exclusive of GST)

Billing Code

3275

For adequate screening tests for porphyria we require:

Blood: 2-5 ml heparinised blood (T34)
Urine: 10-15 ml fresh random specimen
Faeces: A stool minimum 10 g (walnut size)
Specimens should be wrapped in foil, placed in a paper bag and not exposed to direct sunlight.
Urgent samples by arrangement

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