How to test for porphyria

Urine, Faeces and Blood samples

Any doctor can request “porphyrin studies” or “porphyrin screen” and write, for example, “? attack” or “? latent familial” or “symptoms skin rash/lesions” and/or “abdominal pain” or a short case history.

1. Urine 200 ml aliquot from 24 hr urine collection OR Spot sample of at least 100ml preferably first morning midstream. Wrap in foil.

and

2. Faeces: apricot size sample in sealed container, then wrap in foil

and

3. Blood: 10 ml whole blood in (green cap) lithium heparin container, wrapped in foil.

NB in most patients the main abnormalities are found in the faeces and urine. Blood tests may pick up some unusual forms of porphyria.

IMPORTANT:

1.Light protect all samples: Wrap carefully in aluminium foil or a black garbage bag, preferably with a name, time, date sticker on the container and on the outside packing.
LIGHT WILL BREAK DOWN PORPHYRINS AND GIVE AN INVALID TEST RESULT.
2. Keep cool.
3. Send to the Porphyrin laboratory - the quicker the more accurate. Preferably within a day.

When to test: As soon as possible. Test at first suspicion and then test again when the symptoms or attack are at their worst. Testing between attacks can be useful for individual profiling and especially to screen family members. It is better to test when possible and repeat than to put it off. Also note that false negatives are possible especially due to inexperienced handling.

Additional testing is often recommended before, during and after trialing new medication, say 3 days apart. Once there is a clear diagnosis, further tests are only appropriate during acute attacks or exacerbations and if new treatments are being tried.