Normal Urine Specific Gravity Values
The normal range for urine specific gravity in adults is 1.005 to 1.030, with optimal hydration typically showing values between 1.010-1.025. 1
Standard Reference Ranges
- Normal range: 1.005-1.030 across all hydration states 1
- Optimal hydration: 1.010-1.025 for adequately hydrated individuals 1
- First morning urine: ≥1.025 after overnight fluid restriction, which serves as a useful screening measurement of renal concentrating ability 2, 3
Clinical Interpretation by Specific Gravity Value
Dilute Urine (Low Values)
- <1.010 suggests dilute urine in well-hydrated adults 1
- <1.005 persistently may indicate impaired renal concentrating ability and warrants further evaluation 1
Concentrated Urine (High Values)
- >1.025 indicates concentrated urine 1
- >1.030 suggests significant dehydration requiring intervention 1, 2
- ≥1.020 is the threshold used in sports medicine to indicate dehydration, with values below this considered euhydration 1
Measurement Timing Considerations
First morning urine is the preferred specimen for hydration assessment because exercise, diet, and recent fluid intake significantly influence urine concentration 1. If first morning urine cannot be obtained, collect urine after several hours of minimal physical activity and avoid collection after recent fluid consumption or eating 1.
Critical Limitations in Specific Populations
Do not use urine specific gravity to assess hydration status in older adults (Grade A recommendation) 1. Simple signs including urine specific gravity, urine color, skin turgor, mouth dryness, and weight change lack diagnostic accuracy in geriatric populations 1. Instead, use serum osmolality >300 mOsm/kg as the gold standard for dehydration diagnosis in older adults 1.
Measurement Method Considerations
The method used affects accuracy. Refractometry and hydrometry show good correlation with urine osmolarity (r=0.81 and r=0.86 respectively), while reagent strips demonstrate poor correlation (r=0.46) and are not reliable for measuring urine specific gravity 4. Use refractometry or hydrometry rather than reagent strips, and ensure the same method is used for follow-up measurements 4.