To the Editor:— In the June 21 issue (192:1112, 1965), Laurence P. Skendzel, MD replied to a question of Osmolarity of Parenteral Fluids. The answer is well written but I offer the following comments: In the listing of the constituents of lactated Ringer's solution the 109 mEq of chloride has been omitted, thus making the correct answer (272.5 mOsm/liter) not too clear. The mathematics relating to the calculation of the osmolar concentration of 5% glucose in water is incorrect. The 5% glucose in water solution is stated to contain 50 gm/ liter with an osmolarity of 270 mOsm/liter. The mathematics involved (50/180) yields an answer of 277 mOsm/liter. Not sufficiently known to the medical profession is the fact that solutions containing only glucose, made for injection by USP standards, contain the monohydrate form of glucose rather than the anhydrous. Thus a 5% solution of glucose in water contains 45
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