Published in:
Open Access 01-02-2017 | Original Contribution
Urine color as an indicator of urine concentration in pregnant and lactating women
Published in: European Journal of Nutrition | Issue 1/2017
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Aim
Urine concentration measured via osmolality (U
OSM) and specific gravity (U
SG) reflects the adequacy of daily fluid intake, which has important relationships to health in pregnant (PREG) and lactating (LACT) women. Urine color (U
COL) may be a practical, surrogate marker for whole-body hydration status.
Purpose
To determine whether U
COL was a valid measure of urine concentration in PREG and LACT, and pair-matched non-pregnant, non-lactating control women (CON).
Methods
Eighteen PREG/LACT (age 31 ± 1 years, pre-pregnancy BMI 24.3 ± 5.9 kg m−2) and eighteen CON (age 29 ± 4 years, BMI 24.1 ± 3.7 kg m−2) collected 24-h and single-urine samples on specified daily voids at five time points (15 ± 2, 26 ± 1, and 37 ± 1 weeks gestation, 3 ± 1 and 9 ± 1 weeks postpartum during lactation; CON visits were separated by similar time intervals) for measurement of 24-h U
OSM, U
SG, and U
COL and single-sample U
OSM and U
COL.
Results
Twenty-four-hour U
COL was significantly correlated with 24-h U
OSM (r = 0.6085–0.8390, P < 0.0001) and 24-h U
SG (r = 0.6213–0.8985, P < 0.0001) in all groups. A 24-h U
COL ≥ 4 (AUC = 0.6848–0.9513, P < 0.05) and single-sample U
COL ≥ 4 (AUC = 0.9094–0.9216, P < 0.0001) indicated 24-h U
OSM ≥ 500 mOsm kg−1 (representing inadequate fluid intake) in PREG, LACT, and CON.
Conclusions
Urine color was a valid marker of urine concentration in all groups. Thus, PREG, LACT, and CON can utilize U
COL to monitor their daily fluid balance. Women who present with a U
COL ≥ 4 likely have a U
OSM ≥ 500 mOsm kg−1 and should increase fluid consumption to improve overall hydration status.