title: Serum osmolal gap in clinical practice: usefulness and limitations.
abstract: BACKGROUND
  Although serum osmolal gap can be a useful diagnostic tool, clinicians are not familiar with its use in clinical practice.
  
  
  OBJECTIVE
  The review presents in a series of questions-answers and under a clinical point of view the current data regarding the use of osmolal gap.
  
  
  CONCLUSIONS
  The definition and the best formula used for the calculation of osmolal gap, the main causes of increased osmolal gap with or without increased anion gap metabolic acidosis, as well as the role of concurrent lactic acidosis or ketoacidosis are presented under a clinical point of view.
  
  
  CONCLUSIONS
  The calculation of osmolal gap is crucial in the differential diagnosis of many patients presenting in emergency departments with possible drug or substance overdose as well as in comatose hospitalized patients.
authors.affiliation: a Department of Internal Medicine, School of Medicine , University of Ioannina , Ioannina , Greece.
authors.forename: George
authors.initials: G
authors.lastname: Liamis
authors.affiliation: a Department of Internal Medicine, School of Medicine , University of Ioannina , Ioannina , Greece.
authors.forename: Theodosios D
authors.initials: TD
authors.lastname: Filippatos
authors.affiliation: a Department of Internal Medicine, School of Medicine , University of Ioannina , Ioannina , Greece.
authors.forename: Angelos
authors.initials: A
authors.lastname: Liontos
authors.affiliation: a Department of Internal Medicine, School of Medicine , University of Ioannina , Ioannina , Greece.
authors.forename: Moses S
authors.initials: MS
authors.lastname: Elisaf
mesh_terms: D000136:Acid-Base Equilibrium; D000138:Acidosis / Q000097:blood*; D003128:Coma / Q000175:diagnosis; D003937:Diagnosis, Differential; D004636:Emergency Service, Hospital; D006801:Humans; D009994:Osmolar Concentration; D019966:Substance-Related Disorders / Q000175:diagnosis
keywords: Osmolal gap; anion gap; metabolic acidosis; methanol; osmol gap; toxic alcohols