Related Experiment Videos
Discrepancies in osmolal gaps and calculated alcohol concentrations
J D Osterloh1, T J Kelly, H Khayam-Bashi
1Department of Clinical Laboratory Medicine, University of California, San Francisco, USA.
Archives of Pathology & Laboratory Medicine
|July 1, 1996
Summary
Unexplained osmolal gaps (UEOG) during ethanol ingestions are greater than previously reported. This study identified specific causes for discrepancies in osmolal gap calculations, including other alcohols and substances.
Area of Science:
- Clinical Chemistry
- Toxicology
- Internal Medicine
Background:
- Osmolal gap is a calculated measure used to assess the difference between measured and calculated serum osmolality.
- Ethanol ingestion can significantly impact osmolal gap values, necessitating accurate estimation of unexplained osmolal gaps (UEOG).
Purpose of the Study:
- To estimate UEOG during ethanol ingestions after accounting for measured ethanol concentrations.
- To explore and identify the causes of discrepancies in osmolal gap calculations.
Main Methods:
- Analyzed serum specimens for sodium, glucose, urea nitrogen, ethanol, and osmolality using two analytic methods.
- Calculated osmolalities and osmolal gaps using two common formulas (Dorwart and Chalmers, Smithline and Gardner).
- Regressed calculated ethanol concentrations against measured ethanol concentrations to assess formula bias.
Main Results:
- The Smithline and Gardner formula demonstrated a smaller bias (-3.929 +/- 6.623 mOsm/kg) compared to the Dorwart and Chalmers formula (45.217 +/- 6.414 mOsm/kg).
- Using the less biased formula, the mean UEOG was 1.4 +/- 8.5 mOsm/kg, with a 95% upper limit of 18 mOsm/kg.
- Identified outliers with UEOG explained by mannitol, isopropanol, or altered fractional water values.
Conclusions:
- The potential range of osmolal gaps during ethanol ingestions is wider than previously suggested.
- Accurate estimation of UEOG requires careful consideration of the calculation formula and potential interfering substances.