Patterns of urine flow and electrolyte excretion in patients following traumatic brain injury

Abstract

This study was conducted to determine how commonly, following a traumatic brain injury (TBI), patients might lose their circadian rhythm of urine production and to explore possible causes. In health, an adult would be expected to have a daytime rate of urine production twice that of the night. Seven patients, all more than three months post-TBI, who were either continent or in whom continence could be achieved by use of an external device (convene) were investigated. For each patient, over a five-day period, the mean daytime and night-time rates of urine production were measured. These values were expressed as a ratio. In three of the seven patients this ratio did not differ significantly from 1, suggesting that they had lost their normal circadian rhythm of urine production. Screening of pituitary function implicated hypothalamic dysfunction in six of the seven patients, offering a possible explanation for the loss of circadian rhythm seen.