[Interesting urinary findings in acute intermittent porphyria]

The authors describe an uncommon case of a patient with acute intermittent porphyria whose urine on standing, when exposed to light and air, turned dark and eventually black. The reason was increased excretion of porphobilin. The urine continued moreover increased amounts of Thormählen-positive substances, typical melanogens were not detected, however. The authors wish to draw attention to possible diagnostic errors which arise due to erroneous interpretation of laboratory results.