Time of urine sampling may influence the association between urine specific gravity and body composition
Study Details
Previous evidence has found individuals with high fat-free mass to have elevated urine specific gravity (USG) scores 💪
Potentially confounding results for hydration testing ⚠️
This new study assessed whether timing of USG assessments could influence these outcomes 🔍
🍽️ Fasted first-morning (n = 55)
🍳 Non-fasted (n = 51)
…USG samples, were analysed alongside FFM, skeletal muscle mass (SMM) and total body water (TBW) of participants 🩻
(assessed via InBody 770)
Here is what they found ⬇️
Key Findings
Median USG was higher for fasted first-morning samples than non-fasted spot samples 📊
Based on fasted first-morning samples…
📈 41.8% of participants had a USG ≥ 1.020
Comparatively, prevalence of USG ≥ 1.020 was only 21.6% using non-fasted spot samples 📉
None of the body composition variables (FFM, SMM, TBW) were significantly associated with fasted first-morning USG ✅
Whereas, all three variables showed significant, positive associations with non-fasted spot USG ‼️
Plus, no dietary variables were significantly associated with either fasted first-morning or non-fasted spot USG ❌
Conclusion
These findings suggest that timing of USG testing may be the most influential factor in getting reliable hydration status data ⏰
Best practice is likely a first-morning fasted urine sample to get the best results ✅
Reference
https://pubmed.ncbi.nlm.nih.gov/41004465/
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