The Enterotest string test is an easy and non-invasive method for sampling duodenal fluid, which has been successfully used for the analysis of duodenal microflora, as well as biliary
bile acid and
lipid composition. The method was evaluated for determination of
porphyrins in duodenal bile in normal subjects and subjects with
porphyria, following
cholecystokinin induced gall bladder contraction; it is known that analysis of biliary
porphyrins is more discriminatory for the diagnosis of asymptomatic
porphyria than their analysis in faeces or urine. Moreover, serial analysis of bile from patients with
erythropoietic protoporphyria may help in establishing their ability to secrete
protoporphyrin in bile and to assess effects of treatment. The binding of various
porphyrins to Enterotest strings was investigated by incubating pieces of the string in different human bile samples with low to very high
porphyrin concentrations, followed by HPLC analysis of
porphyrins both in the native bile and in extracts obtained from the strings. No differences between
porphyrin composition in native bile and extracts were observed. Duodenal fluid obtained by means of the Enterotest from volunteers not receiving
cholecystokinin showed large variations in
porphyrin patterns not resembling those of native bile.
Mesoporphyrin, a secondary
porphyrin derived from
protoporphyrin by bacteria, was often detectable. These data indicate that the duodenal content without
cholecystokinin injection does not reflect biliary
porphyrin composition. The presence of
mesoporphyrin in the whole intestinal tract, but not in serum and bile, suggests that there is no enterohepatic circulation of secondary
porphyrins. There was close agreement between the
porphyrin ratios found with the standard duodenal intubation technique and the Enterotest, performed simultaneously in one healthy volunteer after induction of gall bladder contraction by
cholecystokinin. From these experiments, it was concluded that fluid adsorbed to the Enterotest string after gall-bladder contraction can be used to determine biliary
porphyrin composition. Since duodenal bile is diluted gall bladder bile, variable
porphyrin concentrations were found when applying the Enterotest in combination with
cholecystokinin in the same subject on successive days. However,
porphyrin ratios, such as the
protoporphyrin to
coproporphyrin I ratio, were relatively constant. In subjects with symptomatic
variegate porphyria, the Enterotest showed highly aberrant
porphyrin patterns, with increased
protoporphyrin to
coproporphyrin I ratios and, in addition, the presence of some unknown
porphyrins. A deviating biliary
protoporphyrin/
coproporphyrin I ratio in one patient appeared to be a useful diagnostic index for the presence of latent
variegate porphyria (or
variegate porphyria in remission).(ABSTRACT TRUNCATED AT 400 WORDS)