The association of urine osmolality with decreased kidney function and/or albuminuria in the United States

Decreased kidney function is commonly caused by hypovolemia. When hypovolemic, the kidney reabsorbs water resulting in concentrated urine. Osmolality is a measure of urine concentration which is more objective than self-reported fluid intake. It has a positive association with hypovolemia. However, it remains controversial whether osmolality is associated with decreased kidney function and/or albuminuria. We conducted a cross-sectional analysis of the 2009-2012 National Health and Nutrition Examination Survey, a standardized survey in the U.S. Participants aged 18-70 years old with random urine osmolality were included. Osmolality was categorized as quartiles. Decreased kidney function was defined by estimated glomerular filtration rate (eGFR)