For diagnosis of an attack of acute porphyria and identification of the type of porphyria, samples of urine, blood and stools (faeces) need to be carefully tested in a laboratory that has an expertise in porphyrias. The tests measure the concentration of porphyrins and related chemicals which will be high in a patient with an attack of acute porphyria. It is important that these tests are carried out as soon as possible after the start of the illness as an accurate diagnosis may be difficult to establish after recovery from an acute attack, especially after several months or years.
In a patient who is known to have inherited an acute porphyria, it may be difficult to decide whether an illness is an attack of acute porphyria or caused by something else. In this situation, urine and, sometimes, other tests can often help your doctor to decide whether you are suffering from an acute attack of porphyria or some other illness. It is important that people with porphyria should not attribute all their illnesses to porphyria. If they do, common but potentially serious conditions like appendicitis may be overlooked.