Test BackgroundThe porphyrias are inherited or acquired disorders of certain enzymes in the haem biosynthetic pathway that is responsible for the synthesis of haemoglobin, myoglobin and cytochrome. They are broadly classified as hepatic porphyrias or erythropoietic porphyrias based on the site of their overproduction and subsequent accumulation (or their chemical precursors).
Clinical Indications Hepatic porphyria: abdominal pain, vomiting, acute neuropathy, seizures and mental disturbances; cardiac arrhythmias and tachycardia may develop as the autonomic nervous system is affected Erythropoietic porphyria: photodermatitis, blisters, necrosis of the skin and gums, itching and increased hair growth
Sample Required EDTA (lavender top) or heparin (green top) protected from light, preferably collect during an attack
Sample Volume 5 mL whole blood
Turnaround Time Up to 6 weeks
NotesNot currently performed in house; this is a referred test. Haemolysed samples are unsuitable for analysis. Separation of cells from plasma makes this less likely if there is a delay in sending the sample to the referral centre.