Variation in hydration status within the normative range is associated with urinary biomarkers of systemic oxidative stress in Guatemalan preschool children.
BACKGROUND
Researchers have increasingly sought noninvasive methods to determine health and nutritional status in humans. Easy and painless to collect, human urine is a source of noninvasive biomarkers.


OBJECTIVE
We aimed to explore the relation between systemic oxidative stress biomarkers excreted in urine and urinary osmolality (Uosm).


METHODS
The current trial was a descriptive, cross-sectional study. We collected seventy-eight samples of 24-h urine in preschoolers who were attending daycare centers in the Western Highlands province of Quetzaltenango, Guatemala. After we measured the total urine volume (Uvol), the aliquot was stored for the later determination of Uosm as a hydration biomarker and to measure 15-isoprostane F2t (F2-Iso) and 8-hydroxydeoxyguanosine (8-OHdG) as biomarkers of cellular oxidation with the use of ELISA assay kits in Spain. Descriptive statistics and linear [Spearman rank-order (rs)] and nonlinear (goodness-of-fit) correlations were performed.


RESULTS
Twenty-four hour Uvols ranged from 65 to 1670 mL, whereas the Uosm varied between 115 and 1102 mOsm/kg. With respect to oxidative biomarkers, the 24-h urinary output of F2-Iso and 8-OHdG had median values of 748 and 2793 ng/d, respectively. The Uvol correlated inversely and significantly with the concentrations of both oxidative biomarkers (F2-Iso rs = -0.603, P < 0.001; 8-OHdG rs = -0.433, P < 0.001), whereas the Uosm was correlated in a direct manner (F2-Iso rs = 0.541, P < 0.001; 8-OHdG rs = 0.782, P < 0.001) when analyzed as a concentration. Associations were weaker when they were analyzed as the total 24-h production.


CONCLUSIONS
Preschool children from the Western Highlands of Guatemala show strong correlations between hydration status measured through the use of Uosm and biomarkers of oxidative stress in urine. Thus, a relatively superior hydration status is associated with a quantitative reduction in urinary excretion of systemic oxidation products. This trial was registered at clinicaltrials.gov as NCT02203890.
Center for the Studies of Sensory Impairment, Aging, and Metabolism, Guatemala City, Guatemala;
María J
http://orcid.org/0000-0002-1012-4715
MJ
Soto-Méndez
Department of Biochemistry and Molecular Biology II, Institute of Nutrition and Food Technology "José Mataix," Center for Biomedical Research, University of Granada, Granada, Spain; and.
Concepción M
http://orcid.org/0000-0002-1451-4788
CM
Aguilera
Department of Biochemistry and Molecular Biology II, Institute of Nutrition and Food Technology "José Mataix," Center for Biomedical Research, University of Granada, Granada, Spain; and.
Laura
L
Campaña-Martín
Department of Biochemistry and Molecular Biology II, Institute of Nutrition and Food Technology "José Mataix," Center for Biomedical Research, University of Granada, Granada, Spain; and.
Victoria
V
Martín-Laguna
Molecular Nutrition Unit, Central Institute for Nutrition and Food Research, Research Center for Nutrition and Food Science, Technical University of Munich, Freising, Germany.
Klaus
K
Schümann
Center for the Studies of Sensory Impairment, Aging, and Metabolism, Guatemala City, Guatemala; clinicanutricion@gmail.com.
Noel W
NW
Solomons
Department of Biochemistry and Molecular Biology II, Institute of Nutrition and Food Technology "José Mataix," Center for Biomedical Research, University of Granada, Granada, Spain; and.
Angel
http://orcid.org/0000-0001-7663-0939
A
Gil
D000080242:8-Hydroxy-2'-Deoxyguanosine; D015415:Biomarkers / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000652:urine; D003430:Cross-Sectional Studies; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000652:urine; D015237:Dinoprost / Q000031:analogs & derivatives; D004326:Drinking; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006166:Guatemala; D006801:Humans; D028421:Isoprostanes / Q000652:urine; D008297:Male; D009752:Nutritional Status; D009994:Osmolar Concentration; D018384:Oxidative Stress; D013030:Spain
D015415:Biomarkers; D028421:Isoprostanes; C075750:8-epi-prostaglandin F2alpha; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003404:Creatinine; D015237:Dinoprost; D003849:Deoxyguanosine
Guatemala; hydration; oxidation; preschool children; urinary osmolality