How to test for porphyria

There are two ways to test: Biochemical and Genetic.

We recommend you print out three copies of the following: one for your doctor, one for your local pathology laboratory, and one to keep so you can all follow the instructions exactly. Remember the doctor or laboratory can ring the porphyrin lab in your state for any confirmation or further info needed.

BIOCHEMICAL TESTING: 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.

See Testing Locations for where to send your samples (or have them forwarded by a commercial lab).

GENETIC TESTING

Important information for Australians.

The following is a statement from the RPA genetics team. To clarify, as we understand it “a known diagnosis” in usual practice would mean, someone in the family with a biochemically confirmed test result for any inherited Porphyria (see our “Why test for Porphyria” page). Another point is that isolating the first family gene can take six months or so.

Porphyria Website Information
Genetic testing is available for individuals with a known diagnosis of an inherited porphyria and their families.

Genetic testing is performed in a stepwise progression, firstly on an affected individual and then if a gene mutation is identified (97% of the time) genetic testing can be offered to at-risk relatives. Children, siblings and extended relatives can then find out whether they have inherited porphyria and take appropriate preventative measures. Although only about one third of people with Porphyria will develop symptoms of the condition they could still pass it on to their children who may or may not suffer from symptoms. There is a clear clinical benefit in knowing whether you have inherited Porphyria or not as avoidance of trigger factors is relatively easy when forewarned.

Genetic testing can be done through Genetic Clinics, which operate in most states of Australia and internationally. A list of Australian Genetic Clinics is available at http://www.genetics.com.au. To see a geneticist you will require a referral letter from your family doctor.

If you have any further questions genetic testing please feel free to contact the genetics team at Royal Prince Alfred Hospital on 02 9515 5062.