YEAST, CREATININE AND FALSE DIAGNOSIS OF PORPHYRIA

A distressingly common occurrence is the erroneous diagnosis of hepati c porphyria in patients with chronic abdominal pain in which either ur inary porphyrins are elevated and/or Watson-Schwarz test is positive. This work investigates a characteristic case and points at possible pi tfalls in establishing a diagnosis. In the patient described, spot uri ne analysis showed positive Watson-Schwarz test and increased porphyri ns at three separate occasions, while normal values of precursors and porphyrins were recorded in 24-hrs. urinary collections during four ho spitalization periods for acute abdominal pain. Various colorimetric a nd HPLC methods employed excluded the diagnosis of porphyria and led t o resolving the discrepancy between home and hospital results. It was found that the false increase in porphyrins in the spot samples emerge d from a substance present in yeast tablets which the patient was cons uming. The positive Watson-Schwarz test obtained was probably the resu lt of the fact that the urine samples were concentrated with creatinin e values exceeding 400 mg%. The case reported above, as well as studie s carried out in three healthy volunteers and in an AIP patient, led t o the conclusion that in order to obtain reliable results, 24-hrs. uri nary collections should be examined, rather than spot urine samples.