Clinical Use
1. Differentiation of type of porphyria
2. Assessment of treatment of patients with PCT
3. Distinguishing true PCT from pseudoporphyria.
Applications
1. Faecal porphyrins may be increased in CEP, PCT, HC, VP, and EPP
2. Results should be interpreted with reference to any other porphyrin results from the patient.
3. Levels may also be increased due to occult bleeding in the gut or dietary sources.
Patient Preparation
None
Sample Preparation
A small, fresh sample of faeces (5-20g) is required. Faecal porphyrin levels decrease rapidly on exposure to light (the half life is 24hrs).
Dispatch samples by first class post in a container that conforms to Post Office regulations, protected from light, to arrive in the laboratory with 24-48 hours of sampling. When a delay in dispatch is anticipated, due to weekend or bank holiday, samples should be stored frozen and protected from light.
Routine requests are assayed within 5 working days after receipt of sample. Urgent requests should be discussed with the laboratory and dispatched via a courier service. Results can be telephoned or faxed as soon as they become available.
Reference Ranges:
Normal: 10 – 200 nmol/g dry wt. (Cardiff)
<50 nmol/g (King’s)
Samples with abnormal total faecal porphyrin levels, for the investigation of pseudoporphyria or the monitoring of treatment for PCT will be analysed by HPLC.
Centres offering this assay
Cardiff UHW Porphyria Diagnostic Service
King’s College Hospital Porphyria Service
References
Frontline tests for the investigation of suspected porphyria. A.C.Deacon & G.H.Elder. J. Clin. Pathol. 2001; 54:500-507
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