What diagnostic tests are available?
There are many laboratory tests available for the porphyrias, and it is often difficult to decide which should be chosen. Many of these tests are expensive. The results are often difficult to interpret. The tests vary in sensitivity and specificity. If a test is “sensitive”, it is unlikely to be falsely negative (that is, fail to diagnose porphyria in a patient who has the disorder). If a test is “specific”, it is unlikely to be falsely positive (that is, diagnose porphyria in a patient who does not have the disorder). Certain tests are both sensitive and specific in patients who have symptoms that are suggestive of a porphyria. It is advisable to have the testing performed by a laboratory that has expertise in the clinical aspects of porphyria and can provide a valid interpretation of the test results. If testing has been performed in laboratories other than porphyria laboratories, consultation with a porphyria expert is advised before a final diagnosis is made.
