A prospective study of thiamine status in patients with severe injuries (injury severity scores greater than 12) showed that they all developed signs of severe thiamine deficiency on the basis of transketolase activity, the standard biochemical test for thiamine deficiency. This occurred within the first week after their injuries despite routine enteral or parenteral feeding including vitamin supplements. This may be due to increased requirements secondary to increased metabolic activity or increased cellular losses. An increased awareness of thiamine requirements and metabolism is essential to avoid the appearance of deficiency syndromes.