The 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).
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
Random urine protected from light, preferably collect during an attack
Measurement of urinary porphyrins alone, even if the results are normal, may not be an adequate investigation of a patient with strongly suspected cutaneous porphyria.