[The total fluids intake, volume of urine and hydration status among young adults from Hebei Province in spring]

Objectives: To investigate the total fluids intake, volume of urine and hydration status among college students from Hebei Province in spring. Methods: In March 2017, the subjects were recruited in a college in Baoding, Hebei Province. 156 students completed the investigation. Total drinking fluids was assessed by 7-day 24-hour fluid intake questionnaire, with a quantitative tool. The water from food was assessed by the duplicate portion method. The urine samples of 24-hour was collected for 3 consecutive days, and the volume, osmolality, pH and specific gravity of urine were measured. Hydration status was grouped to three types according to the urine osmolality (mOsm/kg), namely, optimal hydration (urine osmolality ≤500), middle hydration (500< urine osmolality ≥800) and dehydration (urine osmolality >800), and the differences among subjects in different genders and hydration statuses were compared. Results: The age of all subjects was (19.8±1.1) years old, including 80 male students. The median amounts of total fluids intake, total drinking fluids, water from food and urine volume were 2 324, 1 135, 1 174 and 1 279 ml/d, respectively. The volume of urine among males was 1 272 ml/d, which was not significantly different from that of females (1 304 ml/d) (P>0.05). The osmolality and specific gravity of urine among males were 688 mOsm/kg and 1.017, which were higher than those of females (493 mOsm/kg, 1.014) (P<0.05). But the pH of males was 6.6±0.3, which was lower than that of females (6.7±0.3) (P<0.05). Only 37.2% (n=58) of college students were in optimal hydration status. The median of the amount of total drinking fluids among subjects in optimal hydration status was 301, 448 ml/d higher than that in middle hydration status and dehydration, respectively (P<0.05). The proportion of females in optimal hydration status was 51.3% (n=39), which was higher than that of males 23.8% (n=19) (P<0.05). Conclusion: Large proportion of college students in Hebei had lower total drinking fluids than the recommended intake of China, and the volume of urine was equal to the amount of total drinking fluids among the college students. Only 37.2% of college students were in optimal hydration status, and the proportion of female college students in optimal hydration status was larger than that of males.