Thiamine-deficient lactic acidosis with brain tumor treatment - Report of three cases

Lactic acidosis due to thiamine deficiency is known to complicate chemother apy and radiotherapy treatment of malignant extracranial tumors, but to the authors' knowledge, this complication has not been reported in patients tr eated for malignant brain tumors. They report three such cases, demonstrati ng that this complication can occur during treatment of brain tumors. In all patients, consciousness levels deteriorated within 1 to 2 days. Seru m lactic acid levels increased to concentrations between 62 and 96.7 mg/dl, resulting in severe metabolic acidosis. A low blood thiamine level (9 ng/m l) was demonstrated at the onset in one case, and high-dose thiamine infusi ons dramatically improved lactic acidemia as well as impairment of consciou sness in two cases. In the other case, hydrocephalus was suspected initiall y, resulting in a delay in thiamine supplementation. Clinical differentiation of this form of lactic acidosis from hydrocephalus or tumor progression can be very difficult in a patient undergoing treatme nt for a malignant brain tumor. Demand for thiamine is thought to be increa sed in patients with malignant brain tumors, and supplemental thiamine duri ng treatment is necessary to prevent lactic acidosis. When this complicatio n occurs, immediate treatment with sufficient thiamine is essential, togeth er with normalization of pH by using sodium bicarbonate. With timely interv ention, the level of consciousness can recover to the preacidotic state wit h no new neurological deficits.