Abstract
Type B lactic acidosis complicating malignancies is rare. Increased lactate production from abnormal metabolism of tumor tissue and extensive liver metastases impairing clearance are usual causes. Fluorouracil, commonly used as adjuvant cancer chemotherapy, is not well recognized among drugs that can lead to lactic acidosis. We report a hemodialysis patient, tumor free after surgery for colon carcinoma, developing acute severe lactic acidosis and encephalopathy. Pharmacogenetic studies failed to show common variants predisposing to the more typical patterns of fluorouracil toxicity. Routine monitoring of hemodialysis patients after fluorouracil is the only practical way to detect this potentially lethal complication.