Diagnostic Performance of Afternoon Urine Osmolality to Assess Optimal Hydration Status in an Adult Healthy Population
Abstract: optimal hydration
represents adequate total daily fluid intake to compensate for daily water
losses, ensure adequate urine output to reduce the risk of urolithiasis and
renal function decline, and also avoid the production of arginine vasopressin
(AVP). Twenty-four-hour urine osmolality has been used to assess hydration
status, but it is challenging because of the possibility of spilling urine and
limitation of daily activities. This study is aimed to determine the
performance of the afternoon urine osmolality to assess the optimal hydration
status compared with 24-hour urine osmolality. Methods: a cross sectional study
was conducted on healthy employees aged 18-59 years at Universitas Indonesia
Medical Faculty/Cipto Mangunkusumo Hospital, with consecutive sampling method.
The ROC curve was analyzed to obtain the optimal cut off point and the accuracy
of the afternoon urine osmolality in assessing the optimal hydration status.
Results: between August-September 2016 there were 120 subjects (73.8% female,
median age 32 years) who met the study criteria with a median 24-hour urine
osmolality 463.5 (95% CI, 136-1427) mOsm/kg H2O and median afternoon urine
osmolality 513 (95% CI, 73-1267). We found moderate correlation (r=0.59;
p<0.001) between afternoon urine osmolality and a 24-hour urine osmolality.
Using ROC curve, the AUC value was 0.792 (95% CI, 0.708-0.875) with the cut off
528 mOsm/kg H2O. To assess the optimal hydration status, the afternoon urine
osmolality had the sensitivity of 0.7 (95% CI, 0.585-0.795) and the specificity
of 0.76 (95% CI, 0.626-0.857), Likelihood Ratio (LR) (+) 2.917 (95% CI,
1.74-4.889) and LR (-) 0.395 (95% CI, 0.267-0.583). Conclusion: afternoon urine
osmolality can be used as a diagnostic tool to assess the optimal hydration
status in healthy population with cut off 528 mOsm/kg H2O, sensitivity of 0.7,
and specificity of 0.76.
Keywords: afternoon urine
osmolality; optimal hydration
Author: Ni Made Hustrini,
Parlindungan Siregar, Ginova Nainggolan, Kuntjoro Harimurti
Journal Code: jpkedokterangg170334
