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Sample Advice

Required samples

Selection of the correct set of samples is essential for accurate diagnosis of the porphyrias.  Details of presenting symptoms and any relevant family and/or past history should also be provided.

When supplying family details please include the type of porphyria, dates of birth and the relationship to the patient.   Unfortunately we are unable to accept samples for analysis directly from patients.

Please be aware that our test selection policy is designed to minimise the number of tests performed at the onset of our investigation. Selection is dependant on the supply of relevant clinical details and appropriate samples (please refer to the Sample Choice Strategies link on the right hand side of the page).

In the absence of clinical details it will be necessary to carry out a greater range of analyses to exclude or make a diagnosis and this will incur greater costs for what may be unnecessary testing.

We will perform the tests we deem necessary to exclude or make a diagnosis or to monitor treatment of known porphyriac patients, unless we are specifically instructed not to do so by the referral laboratory.

Genetic mutation analysis is carried out only on patients with an unequivocal diagnosis of porphyria or patients who have a family member with a previous, confirmed diagnosis of porphyria. Informed consent is required from both the patient and relatives involved, by completion of the referring clinician's consent procedure or the Porphyria Genetic consent Form. Following analysis any remaining DNA is permanently stored and may be used for quality control purposes.

Sample labelling requirements

UHB policy states that: "All samples must be labelled clearly and legibly with the patient's name, date of birth, hospital number (if known) and the date of collection. Each request should be accompanied by an appropriate request form fully completed and signed by the requesting medical officer". Please also ensure that the primary sample is labelled prior to protection from light.

Further advice on sample choice can be found on the Sample Choice Strategies link on the right hand side of this page, and also see: 

Transport of samples to Cardiff

Samples should be sent by first class post in UN3373 packaging (Biological substance, category B) to the following address:

Unfortunately, due to the high cost of postage we cannot return sample boxes unless a pre-paid postage label is provided.

Samples exposed to light

Samples that are not wrapped to protect them from light exposure but are received in your lab less than 6 hours after collection can be assayed. We would suggest you add a comment to the request form stating that exposure to light has occurred. We will include this on the report and advise that the results should be interpreted taking this into account. This will allow the requesting clinician to decide whether they wish to repeat the tests. However in patients with active porphyria porphyrin concentrations are greatly increased and would remain detectable despite light exposure over this time period.

Samples exposed to light for greater than 6 hours should not be assayed. The samples should be discarded and repeat samples requested straight away, particularly if the patient is on-site.

Please contact us if you would like to discuss individual cases as factors such as patient symptoms, type of porphyria suspected, family history of porphyria and sample availability may inform further advice.

High risk samples

All specimens and request forms should be marked by a plain yellow sticker, a "high risk" label or clearly marked "high risk". These specimens should be double bagged and posted to the Porphyria Service in a Post Office approved transport container.

Turn around times

We aim to complete a full porphyria screen within 7 to 15 working days from receipt of the samples to posting the report back to the referral centre. However, some investigations may take longer due to lack of clinical details, family history or the need for more extensive investigation.

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