<prompt> The normal range of serum osmolality in mOsmL:270 to 285300 to 320350 to 375200 to 250  <response>: Normal serum osmolality ranges from 270-285 mOsmL while in neonates, serum values as low as 266 mOsmkg . And normal urine osmolality ranges from 40-1400 mOsmL. Ref: Harrisons Principles of Internal Medicine, 16th Edition, Page 252; Handbook of Fluid, Electrolyte, and Acid-Base Imbalances By Joyce LeFever Kee, Betty J. Paulanka, Carolee Polek, 2009, Page 8. 