Endotoxaemia as a cause of fever in immunosuppressed patients.

Using a recently developed chromogenic substrate assay sensitive to 10 pg/ml Escherichia coli endotoxin in plasma, systemic endotoxaemia was found in 52% of 21 episodes of fever in patients with a haematological malignancy who were infected. Endotoxaemia was also found in 27% of 22 episodes of fever of unknown origin. In 45 afebrile patients neither neutropenia nor cytotoxic chemotherapy was a cause of endotoxaemia. Passage of endotoxin from portal blood into the systemic circulation can contribute to unexplained fever in immunosuppressed patients.