Screening is the first step Many tests are offered for the
diagnosis of one of the porphyrias. One might think that this is
an advantage in diagnosing porphyrias. However, it may be
difficult to choose the proper tests and interpret the results,
resulting in delay in diagnosis and even misdiagnosis of
Porphyria. Tests may be overused, leading to unnecessary
expense. In the past, it was customary to obtain many or all
available tests when Porphyria was suspected and then examine
patterns of any abnormal results. Abnormal results might be
compared with tables showing patterns of abnormalities to be
expected in the various Porphyrias. This approach did not
adequately consider the sensitivity and specificity of the
various tests or how abnormal the results should be for making a
diagnosis of Porphyria. A better and less costly approach is to
rely on a few screening tests that are both sensitive and
specific. If a well-chosen screening test is normal, the
possibility of Porphyria as a cause of symptoms is effectiv