# A Comparative Analysis of Hydration Status Among Urban and Rural Adults in Selangor, Malaysia

## TL;DR

This study compared hydration levels between urban and rural adults in Malaysia and found that rural adults are less hydrated, with urine tests being more reliable than blood tests for measuring hydration.

## Contribution

The study provides new empirical evidence on hydration status differences between urban and rural populations in Malaysia and evaluates the reliability of hydration biomarkers.

## Key findings

- Rural adults showed lower hydration levels compared to urban adults based on urine and blood measurements.
- Urine specific gravity and osmolality in first-morning urine strongly correlate with 24-hour urine samples, indicating their reliability.
- Blood tests revealed significant differences in hematocrit, sodium, potassium, and eGFR between urban and rural adults.

## Abstract

Background and aim: Adequate hydration is essential for overall health; however, data on hydration status among Malaysian adults are limited. This study aimed to compare the hydration status of urban and rural adults in Selangor, Malaysia.

Methods: A cross-sectional study was conducted involving participants from urban (n=189) and rural (n=188) areas near Universiti Putra Malaysia (UPM), selected through purposive sampling. The study included 377 healthy adults aged 18-59 years (mean {SD}: 31.34 {11.64} years). Participants with health conditions, such as diabetes, hypertension, gastrointestinal diseases, kidney disorders, and cardiovascular issues, were excluded. Additionally, individuals taking prescription medications, food supplements, consuming high levels of caffeine or alcohol, smoking heavily, or engaging in intense aerobic training were also excluded. Sociodemographic data were collected, and hydration status was assessed using urine samples (first-morning and 24-hour) and blood tests (plasma osmolality, blood count, and renal function). Urine measurements included specific gravity (USG), osmolality (UOSM), volume (UVOL), and colour (UCOL), which were compared against hydration biomarkers. Chi-square tests and independent t-tests (p<0.05) were employed to compare sociodemographic characteristics and hydration status between urban and rural adults. Factor analysis was used to assess the reliability of hydration measurements.

Results: Significant differences were observed in USG, UOSM, and UVOL of first-morning urine samples (χ²{2}=6.537, p=0.038; χ²{1}=6.465, p=0.011; t{375}=-2.10, p=0.036). Additionally, significant differences in USG and UOSM of 24-hour urine samples were noted between urban and rural adults (χ²{2}=27.686, p=0.000; χ²{2}=11.030, p=0.000). Blood tests revealed significant differences in hematocrit (HCT) (t{375}=-1.987, p=0.048), sodium concentration (Na) (t{375}=-4.468, p=0.000), potassium concentration (K) (t{375}=3.563, p=0.000), and estimated glomerular filtration rate (eGFR) (t{371.96}=-4.247, p=0.000) between urban and rural adults. The results indicated that rural adults are less hydrated than their urban counterparts. Factor analysis confirmed that urine measurements are strong indicators of hydration status (quality scores >1), with USG and UOSM in first-morning urine (FMU) showing a strong positive correlation with 24-hour urine samples (0.999), indicating that urine tests are more reliable than blood tests for assessing hydration status.

Conclusion: This study found significant differences in hydration status between urban and rural adults in Selangor, Malaysia, based on both urine and blood measurements; however, urine tests proved to be more reliable for assessing hydration levels. These findings may inform strategies to improve hydration among Malaysian adults. Further research is warranted to investigate factors influencing hydration status.