[Rotor syndrome: relevance of the determination of coproporphyrin isomers in the urine in comparison with intrahepatic (alcohol-induced) cholestasis].

Porphyrin isomer examinations have been performed in two patients with Rotor syndrome (RS), one patient with Gilbert-Meulengracht syndrome and 12 patients with alcohol toxic cholestasis. Under both conditions, cholestasis and RS, total urinary coproporphyrin excretion as well as coproporphyrin isomer I was relatively and absolutely increased. Despite the different degree of the increase of coproporphyrin isomer I excretion between RS (69 vs. 72%) and cholestasis (47% on average), there are single cases with a coproporphyrin isomer I portion around 60%. In such cases, the differential diagnosis is quite difficult, so that the diagnosis "Rotor syndrome" should never be gained by one distinct examination; it is a diagnosis performed by exclusion of other diseases.