What is the osmolality of plasma if Serum sodium is 135 mEq/L, serum glucose is 120 mg/dL and BUN is 24 mg/dL?

Because of the predominant role of the major solutes and the detion of plasma from an ideal solution, one can ordinarily approximate the plasma osmolality within a few mosm/liter by using the following formula, in which the constants conve the clinical units to millimoles of solute per liter: Osmolality (mOsm/L) = 2 (mEq/L) + 0.055 (mg/dL) + 0.36 (mg/dL) Ref: Ganong's Review of Medical Physiology 23rd edition, Chapter 1.