ACUTE PORPHYRIA - DIAGNOSIS

Acute porphyria should be considered in any patient presenting with unexplained abdominal pain, mental dysfunction or peripheral neuropathy. A further clue to the diagnosis is discolouration of the urine. During an attack, the urine is a dark reddish brown and this becomes more pronounced if it is left standing. A simple bedside test can confirm the diagnosis. Quantitative studies of the different porphyrins and precursors in the urine and faeces should be performed later by a specialist laboratory to identify the particular type of acute porphyria.

Successful treatment of an acute attack of Porphyria depends largely on, early diagnosis, removal of precipitating factors, and provision of intensive supportive therapy. On first diagnosing an attack, a careful search should be made for any precipitating factors, and if possible, these should be removed. The patient's current drug therapy should be scrutinised and a search made for any underlying infection. When appropriate, a pregnancy test should be performed.

Screening of Families

Latent cases in affected families may be diagnosed, either by measurement of porphyrins and their precursors in urine, faeces and blood, or by measurement of the activities of the enzymes of the Haem biosynthetic pathway. Where such screening is required, most Analytical Laboratories, such as our own, prefer to receive samples of urine, stool and heparinized blood. Prophylaxis is extremely important. In particular, Drugs listed in the 'Unsafe Groupings' in Tables 1 and 2, should be avoided. Patients should also be counselled on the dangers of alcohol, smoking and dieting.

A Preliminary Test for The Presence of Porphobilinogen in the Urine

Equal volumes of Urine and Ehrlich's reagent (An acidic solution of p-dimethyl aminobenzaldehyde) are mixed in a tube. If the solution takes a pink colouration, this indicates the presence of porphobilinogen or urobilinogen. The presence of porphobilinogen may be confirmed by the addition of about 2 volumes of chloroform to the solution and shaking thoroughly. When the mixture is allowed to stand and separate the pink colouration should have remained in the upper aqueous layer. If it moves to the lower chloroform layer the colouration is due to urobilinogen and not porphobilinogen. When urobilinogen concentrations are high it may be necessary to repeat the extraction.