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Three Part Question

In [adults previously diagnosed with an acute porphyria presenting to the emergency department with a suspected acute attack] is [measurement of urinary porphobilinogen] effective in [diagnosing an acute porphyric attack]?

Clinical Scenario

A 36 year old female presents to the ED with abdominal pain and vomiting after a week of crash dieting. She tells you she has been previously diagnosed with an acute porphyria but has never experienced these symptoms before. You remember reading that urinary porphobilinogen is raised in the acute attack. You wonder if this is of use in diagnosing the acute attack?

Search Strategy

Medline 1966-06/06, Embase 1980-6/06 and Cinahl 1982-06/06 via Ovid.
Medline:[urin$ adj porphobilinogen.mp. or urin$ adj PBG .mp. or Watson schwartz.mp. or watson-schwartz.mp. or hoesch.mp. or mauzerall granick.mp.or trace PBG kit.mp.] AND [exp Porphyrias/ or porphyrias.mp. or porphyria.mp.or AIP.mp.] LIMITS humans and english
Embase and Cinahl: [urin$ adj porphobilinogen.mp. or urin$ adj PBG .mp. or Watson schwartz.mp. or watson-schwartz.mp. or hoesch.mp. or mauzerall granick.mp.or trace PBG kit.mp.] AND [exp Porphyria/ or porphyrias.mp. or porphyria.mp.or AIP.mp]
Cochrane Library-porphyria

Search Outcome

Medline:41 results- 0 relevant
Embase:79 results - 1 relevant
Cinahl: 0 results
Cochrane Library:32 results- 0 relevant

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Kauppinen R, Fraunberg G 2002 Finland	380 patients were classified into four groups: AIP patients in acute attack, symptomatic AIP patients in remission, symptom free AIP patients, healthy relatives. Criteria for an acute attack were the acute nature of the symptoms, urinary PBG excretion at least 5 imes the upper limit of the reference interval, severe abdominal or other pain associated with one or more typical porphyric symptoms. All patients had urinary PBG measured.	Systematic follow up of all Finnish patients known to have AIP.	Comparison of urinary PBGs	Considerable overlap between patients suffering symptoms of acute attack and patients in remission.	PBG values only given in a graph. Classification of groups unclear- what defined a symptomatic AIP patient in remission?

Comment(s)

The graph comparing the PBG of patients with AIP in remission and having an acute attack clearly showed a considerable overlap between the two groups. Therefore although there are tests that measure the urinary PBGs, given the overlap in the urinary PBGs it is would be impossible to say with any certainty if a patient were having an acute attack or not.

Clinical Bottom Line

The measurement of urinary PBG is not effective at diagnosing the acute porphyric attack as patients in remission often have a high PBG.

References

1. Kauppinen R, Fraunberg G Molecular and Biochemical Studies of AIP in 196 patients and their families. Clinical chemistry 2002;48:1891-1900