A pilot study to assess if urine specific gravity and urine colour charts are useful indicators of dehydration in acute stroke patients

AIM: The purpose of this pilot study was to examine whether urine specific gravity and urine colour could provide an early warning of dehydration in stroke patients compared with standard blood indicators of hydration status.BACKGROUND: Dehydration after stroke has been associated with increased blood viscosity, venous thrombo-embolism and stroke mortality at 3-months. Earlier identification of dehydration might allow us to intervene to prevent significant dehydration developing or reduce its duration to improve patient outcomes.METHODS: We recruited 20 stroke patients in 2007 and measured their urine specific gravity with urine test strips, a refractometer, and urine colour of specimens taken daily on 10 consecutive days and compared with the routine blood urea:creatinine ratios over the same period to look for trends and relationships over time. The agreement between the refractometer, test strips and urine colour were expressed as a percentage with 95% confidence intervals.RESULTS: Nine (45%) of the 20 stroke patients had clinical signs of dehydration and had a significantly higher admission median urea:creatinine ratio (P = 0·02, Mann-Whitney U-test). There were no obvious relationships between urine specific gravity and urine colour with the urea:creatinine ratio. Of the 174 urine samples collected, the refractometer agreed with 70/174 (40%) urine test strip urine specific gravity and 117/174 (67%) urine colour measurements.CONCLUSIONS: Our results do not support the use of the urine test strip urine specific gravity as an early indicator of dehydration. Further research is required to develop a practical tool for the early detection of dehydration in stroke patient