In order to test the hypothesis that urine colour can be used as an index o
f hydration in critically ill patients, we selected 40 intensive care and h
igh-dependency patients and correlated urine colour (scored on an eight-poi
nt scale) with various indices of hydration: urine:plasma sodium, osmolalit
y and urea ratios, urine output and central venous pressure. In addition, w
e compared the colour-chart score with scores made by intensive care nurses
(without the benefit of a colour chart) in order to test subjective assess
ment of urine colour. There were weak but statistically significant correla
tions between urine colour and urine output (Spearman's r = - 0.555) and be
tween urine colour and urine:plasma sodium ratio (Spearman's r= - 0.459). S
ubjective assessment of urine colour appeared to be reliable. Thus, althoug
h urine colour does vary with hydration in the critically ill, assessment o
f urine colour adds little to the overall assessment of hydration in this g
roup of patients.