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.
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 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.
Urine
20ml, fresh, preferably early morning urine in a universal container, protected from light
Faeces
A small portion, 5-10g wet weight, in a universal container, protected from light.
Blood
5-10mL EDTA blood protected from light.
Further advice on sample choice can be found in the following documents:
Sample Choice
Cardiff Porphyria Service reference range
Porphyria Specimen Request Form
Analytes/tests available
Urine
Total porphyrin
Porphobilinogen
Aminolevulinic acid
Precursor fractionation
Faeces
Total porphyrin
Precursor fractionation
Plasma
Fluorescence emission screen
Total porphyrin
Red blood cell
Fluorescence emission screen
Total protoporphyrin
Porphobilingen deaminase
Genetic analysis
Coproporphyrinogen oxidase; CPOX
Uroporphyrinogen decarboxylase; UROD
Protoporphyrinogen oxidase; PPOX
Hydroxymethylbilane synthase; HMBS
Uroporphyrinogen III synthase; UROS
Ferrochelatase; FECH
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 10 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.
Bovine porphyria
We offer biochemical screening for erythropoietic protoporphyria (Bovine EPP) in Limousin cattle (1) and congenital erythropoietic porphyria (Bovine CEP) in Longhorn cattle (2). A 5-10ml EDTA blood sample is required (please ensure the primary tube is labelled and light protected).
In order to mininise the cost our first-line test is fluoresence emission spectroscopy detection in plasma. If the sample is haemolysed we screen for protoporphyrin in erythrocytes. If, as is carried out for human patients, you require both plasma and erythrocyte screens please state this clearly on the request form.
To request a price list please email CAV_porphyria@wales.nhs.uk.
Refs:
1. G R Ruth, S Schwartz and B Stephenson. Bovine protoporphyria: the first non-human model of this hereditary photosensitising disease. Sciens. 1977;198:199-201.
2. J N Huxley, R L lloyd, C S Parker, J R Woolf and B W Strugnell. Congenital erythropoietic porphyria in a Longhorn calf. Veterinary Record. 2009;23:694-5.
Veterinary Laboratories Agency information sheet
