Turner White CommunicationsAbout TWCSubscribeContact TWCHomeSearch
Hospital PhysicianJCOMSMPBRMsCart
Current Contents
Past Issue Archives
Interactive:
Self-Assessment Questions
Review of
Clinical Signs
Clinical Review
Quiz
Pediatric Rounds
Resident Grand Rounds
Article Archives
Case Reports
Clinical Practice
Exams
Pediatric Rounds
Resident Grand Rounds
Review of
Clinical Signs

Guide to Reading
Hospital Physician
Editorial Board
Information for Authors

Reprints, Permissions, & Copyright
Site Map
Self-Assessment Questions

Emergency Medicine


Answer 5
  1. 52 mOsm/L. Serum osmolarity can be calculated using the following formula: Serum osmolarity = 2(sodium) + glucose/18 + BUN/ 2.8 + ethanol/4.6 + mannitol/18 This patient’s calculated osmolarity is approximately 300 mOsm/L. The patient’s osmolar gap can be obtained by subtracting the calculated serum osmolarity from the measured serum osmolarity (352- 300 = 52). Thus, the patient has an osmolar gap of 52 mOsm/L. An osmolar gap occurs when a solute other than sodium, glucose, or urea is added to the plasma. When another solute is present, the osmolarity calculated from the above formula will be less than the actual measured value, causing an osmolar gap. An osmolar gap of 25 mOsm/L or greater is highly suggestive of ethylene glycol or methanol intoxication. Both of these intoxications should be entertained as etiologies of this patient’s symptoms.

Click here to return to the questions

 

Hospital Physician     JCOM     Seminars in Medical Practice
Hospital Physician Board Review Manuals
About TWC    Subscribe    Contact TWC    Home    Search   Site Map

Copyright © 2009, Turner White Communications
Updated 1/04/08 • kkj