Dehydration Status Aggravates Early Renal Impairment in Children: A Longitudinal Study

Abstract

Dehydration is common in children for physiological and behavioral reasons. The objective of this study was to assess changes in hydration status and renal impairment across school weekdays. We conducted a longitudinal study of three repeated measures of urinalysis within one week in November 2019 in a child cohort in Beijing, China. We measured urine specific gravity (USG) to determine the dehydration status, and the concentration of β2-microglobulin (β2-MG) and microalbumin (MA) to assess renal function impairment among 1885 children with a mean age of 7.7 years old. The prevalence of dehydration was 61.9%, which was significantly higher in boys (64.3%). Using chi-square tests and linear mixed-effects regression models, we documented the trends of the renal indicators’ change over time among different hydration statuses. Compared to Mondays, there were apparent increases of β2-MG concentrations on Wednesdays (β = 0.029, p < 0.001) and Fridays (β = 0.035, p < 0.001) in the dehydrated group, but not in the euhydrated group. As for the MA concentrations, only the decrease on Fridays (β = −1.822, p = 0.01) was significant in the euhydrated group. An increased trend of elevated β2-MG concentration was shown in both the euhydrated group (Z = −3.33, p < 0.001) and the dehydrated group (Z = −8.82, p < 0.001). By contrast, there was a decreased trend of elevated MA concentrations in the euhydrated group (Z = 3.59, p < 0.001) but not in the dehydrated group. A new indicator ratio, β2-MG/MA, validated the consistent trends of renal function impairment in children with dehydration. Renal impairment trends worsened as a function of school days during the week and the dehydration status aggravated renal impairment during childhood across school weekdays, especially tubular abnormalities in children.

Interaction of Hydration Status and Physical Activity Level on Early Renal Damage in Children: A Longitudinal Study

“…We observed stable and consistent longitudinal associations between hydration status and renal stress; children with euhydration were less likely to have tubular or glomerular damage. This finding is consistent with our previous study ( 21 ). Moreover, a decreasing temporal trend over the school week of MA only in the children with euhydration ( 21 ).…”

“…A cross-sectional study of 141 adolescents aged 15–17 years reported that 90% of were dehydrated during school as determined by urine SG ( 32 ). Dehydration and inadequate water intake can affect the school performance including alertness, concentration, and fatigue ( 32 ), can impair renal function ( 21 ), and can even lead to chronic kidney disease ( 2 ). We observed stable and consistent longitudinal associations between hydration status and renal stress; children with euhydration were less likely to have tubular or glomerular damage.…”

“…Specific gravity (SG), β 2 -microglobulin (β 2 -MG), and microalbumin (MA) were measured via urinalysis panels A and B. Urinalysis panel A includes urobilinogen, bilirubin, ketone, occult blood, protein, nitrite, white blood cells, sugar, SG, pH, color, and turbidity; urinalysis panel B includes β 2 -MG, microalbumin, potassium, sodium, uric acid, and creatinine. Dehydration status of participants was defined as SG ≥ 1.020, with euhydration status defined as SG < 1.020 ( 4 , 21 ). Renal tubular damage was defined as elevated β 2 -MG > 0.2 mg/L ( 24 ), and glomerular damage was defined as elevated MA ≥20 mg/L ( 25 ).…”

“…Associations between PA and hydration status and their interactions with renal disease have been inconsistent across studies and populations ( 17 – 20 ). We have reported previously that dehydration status aggravated renal impairment over the school week days, notably tubular abnormalities ( 21 ). To our knowledge, there are no studies investigating the interaction of hydration status and PA level on renal damage in schoolchildren.…”

Insufficient Fruit and Vegetable Intake and Low Potassium Intake Aggravate Early Renal Damage in Children: A Longitudinal Study

“…In both the unadjusted analysis and those that adjusted for age, sex, BMI, SBP, sleep duration, screen time, and physical activity, we observed consistent longitudinal positive associations between insufficient FVI (<4/d) and urinary β 2 -MG excretion, but not urinary MA excretion. This finding suggests that insufficient FVI leads to earlier renal tubular stress than glomerular stress, and evidence suggests tubular damage precede glomerular damage [ 31 ]. Clinical management practices in CKD patients with glomerular or tubular abnormalities include dietary intervention with base-producing foods such as fruits and vegetables to increase potassium absorption [ 9 ] and reduce metabolic acidosis [ 32 ].…”