osmolal gap


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Related to osmolal gap: osmolar gap

osmolal gap

[ozmōl′əl]
a difference between the observed and calculated osmolalities in serum analysis. The calculated osmolar values include sodium concentration multiplied by 2, plus glucose and blood urea nitrogen.

osmolal gap

The difference between the measured osmolality of the plasma, and the calculated osmolality of the plasma (plasma glucose/18 + blood urea nitrogen/2.8 + sodium*2). A gap is present when the difference exceeds 10 mmol/kg of water. Osmolal gaps are present when unmeasured osmotically active solutes, such as toxins, e.g., methanol or ethylene glycol, are present in the plasma.
See also: gap

osmolal

adjectival form of mole, a one osmolal solution contains 1 mole of solute in 1 L of water.

osmolal gap
difference between the measured plasma osmolality and the osmolality calculated from the plasma concentration of normally measured solutes.
References in periodicals archive ?
Because of the difficulty in obtaining EG concentrations, an osmolal gap of <10 mOsm/kg is often used as a surrogate marker for when it is safe to stop treatment.
Because he presented early, the initial test results showed a large osmolal gap, but the patient had not yet developed an anion gap acidosis.
In a patient with an increased osmolal gap and normal anion gap, can EG poisoning be ruled out?
High anion gap metabolic acidosis and an increased serum osmolal gap in patients with a history of alcoholism can be due to methanol or ethylene glycol intoxication, lactic acidosis, and alcoholic or diabetic ketoacidosis.
The metabolic acidosis and increased serum osmolal gap are also not always present together.
Inherent problems with the measured osmolality and calculation of the osmolal gap reduce the reliability of these measurements in the differential diagnosis of volatile and ethylene glycol alcohol intoxication in patients.
In a patient with an established metabolic acidosis from toxic alcohol ingestion, a normal or low osmolal gap can occur if blood is sampled after the volatile alcohols have been converted to the acid metabolites (59).
At a given time after ingestion, the concentrations of the remaining ethylene glycol and the accumulated acidic metabolites affect the magnitude of the osmolal gap and anion gap, respectively.
The osmolal gap is also an estimate of unmeasured constituents in the serum.