Osmolgap

Osmolgap refers to the difference between the measured serum osmolality and the calculated serum osmolality. Serum osmolality is a measure of the concentration of solute particles in the blood, and it plays a crucial role in maintaining fluid balance and regulating body water.

The osmol gap is typically calculated using the formula: Calculated Osmolality = 2 * (Serum Sodium) + (Blood Urea Nitrogen / 2.8) + (Glucose / 18). This formula accounts for the major contributors to serum osmolality. The measured osmolality is determined using an osmometer.

An elevated osmol gap, meaning the measured osmolality is significantly higher than the calculated osmolality, can indicate the presence of unmeasured osmoles in the serum. These unmeasured osmoles can include substances like ethanol, methanol, ethylene glycol, isopropyl alcohol, mannitol, or certain toxins. A widened osmol gap is a clinically significant finding and often prompts further investigation to identify the underlying cause. A normal osmol gap is generally considered to be less than 10-15 mOsm/kg. A very large osmol gap can suggest severe poisoning. The osmol gap is a valuable tool in the diagnosis and management of various medical conditions, particularly those involving intoxication or metabolic disturbances.