There are no official guidelines to assist in answering this question. I will search for relevant research papers instead.
From the Research
Urine Specific Gravity (USG) of 1.031
- A USG of 1.031 indicates a highly concentrated urine sample, which may suggest dehydration or inadequate fluid intake 1.
- This value is above the normal range, which typically falls between 1.020 and 1.030 2, 3.
- A study comparing digital and optical hand-held refractometers for measuring feline urine specific gravity found a mean USG of 1.031 using an optical refractometer, which was significantly higher than the mean USG of 1.027 obtained using a digital refractometer 4.
- In humans, a USG of 1.031 may be associated with kidney impairment or dehydration, particularly in individuals working in hot or ultra-low humidity environments 1, 3.
- The diagnostic role of USG in detecting kidney impairment has been investigated, with a cut-off value of ≥1.018 showing sensitivity and specificity for detecting elevation of urinary nephrin levels 3.
- However, it is essential to consider the measurement method used, as different techniques (e.g., hydrometry, refractometry, and reagent strips) may yield varying results 5, 2.