====== Urine osmolality ======


Urine [[osmolality]] is used to measure the number of dissolved particles per unit of water in the [[urine]]. As a measure of urine concentration, it is more accurate than specific gravity. Urine osmolality is useful in diagnosing disorders of urinary concentration such as [[diabetes insipidus]] and in assessing [[hydration]] status. Often, the assessment of any disorder involving [[antidiuretic hormone]] (ADH) will require both serum and urine osmolality to assess the concentrating ability of the kidney.

The normal 24-hour urine osmolality is, on average, 500-800 mOsm/kg of water. Random urine osmolality should average 300-900 mOsm/kg of water. After 12-14 hours of fluid intake restriction, the urine osmolality should exceed 850 mOsm/kg of water.