Plasma Porphyrin

Clinical Use
1. Determination of the type of porphyria
2. This assay is not useful for detection of acute porphyrias in children less than 12 years old.

 Plasma porphyrins are raised during active porphyria episodes and in some cases of porphyria also during asymptomatic phases.
2. A negative screen does not exclude porphyria.
3. Distinguishing between true porphyria and raised plasma porphyrins due to secondary causes.
4. Monitoring porphyria in anuric patients

Patient preparation

Sample Preparation
5-10ml of fresh EDTA anti-coagulated blood. Plasma porphyrin levels decrease rapidly on exposure to light (the half life is 24hrs).
The minimum volume required for assay is 5ml – allowing for both screening and quantitation if necessary. Paediatric investigations should be discussed with the laboratory.

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 at 0-40C 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:
< 11.2nmol/L

Centres offering this assay
Cardiff UHW Porphyria Diagnostic Service
King’s College Hospital Porphyria Service

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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