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Chemical Pathology

Notes

The porphyrias are a group of rare inherited or acquired disorders in which a deficiency in one of the enzymes involved in porphyrin synthesis results in decreased formation of haem, and accumulation of excess porphyrins or their precursors.

Sample requirements

  • The appropriate specimen type(s) required is dependent on initial clinical presentation and investigations required.
  • Refer to European Porphyria Network for further information/details or contact the duty biochemist to discuss.
  • Once required samples ascertained, refer to sample tube details below
  • All samples must be protected from the light.

Blood

Blood taken into an 4mL EDTA tube (PROTECTED FROM LIGHT)

EDTA with cap

Urine

Early morning urine collected into 30mL Universal (PROTECTED FROM LIGHT)

30ml universal container

Faeces

Minimum 5g faeces collected into blue top stool pot (PROTECTED FROM LIGHT)

Stool container with spoon

Storage/transport

Send at ambient temperature to the laboratory on the day of collection, and protected from the light (wrap in foil or brown paper). Do not store.

Required information

Relevant clinical details including any details of family history.

Turnaround times

Samples are sent for analysis to King's College Hospital, London. Results are expected back within 3 weeks.

Reference ranges

Reference ranges are provided by the referral laboratory:

Test Performed Reference Range
Plasma Porphyrins <11.2 nmol/L
Faecal Porphyrins <50 nmol/g stool
Total Urine Porphyrins (random) <320 nmol/L
Total Urine Porphyrin:creatinine ratio <35 nmol/mmol
Total Urine Porphyrin (24 hour collection) <410 nmol/24hr
Red Cell Free Protoporphyrin 0-200 nmol/L cells
Red Cell Zinc Protoporphyrin 0-800 nmol/L cells

Further information

To learn more about porphyrins or porphyria visit Lab Tests Online or British Porphyria Association

See also : Drug database for Acute Porphyria

Page last updated: 05/02/2019