Osmolar Gap Calculator

Osmolar Gap Equation:

\[ OG = MO - O_{serum} \]

Osmolar Gap (OG):

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1. What is the Osmolar Gap?

The Osmolar Gap is an indication of unmeasured solute in the blood. It represents the difference between measured osmolality and calculated serum osmolality, helping to identify the presence of osmotically active substances not accounted for in the standard calculation.

2. How Does the Calculator Work?

The calculator uses the Osmolar Gap equation:

\[ OG = MO - O_{serum} \]

Where:

\( OG \) — Osmolar Gap (mOsm/kg)
\( MO \) — Measured Osmolality (mOsm/kg)
\( O_{serum} \) — Calculated Serum Osmolality (mOsm/kg)

Explanation: The equation calculates the difference between the laboratory-measured osmolality and the theoretically calculated serum osmolality based on standard formulas.

3. Importance of Osmolar Gap Calculation

Details: Osmolar Gap calculation is crucial for detecting the presence of toxic alcohols and other unmeasured osmotically active substances in the blood, aiding in the diagnosis of poisoning and metabolic disorders.

4. Using the Calculator

Tips: Enter measured osmolality and calculated serum osmolality values in mOsm/kg. Both values must be valid non-negative numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal Osmolar Gap range?
A: A normal Osmolar Gap is typically less than 10 mOsm/kg. Values greater than 10-15 mOsm/kg may indicate the presence of unmeasured osmoles.

Q2: What substances can cause an elevated Osmolar Gap?
A: Ethanol, methanol, ethylene glycol, isopropanol, acetone, and other volatile alcohols can cause an elevated Osmolar Gap.

Q3: When should Osmolar Gap be measured?
A: Osmolar Gap should be measured when toxic alcohol ingestion is suspected, in cases of unexplained metabolic acidosis, or when there is suspicion of osmotically active substance presence.

Q4: Are there limitations to Osmolar Gap interpretation?
A: Yes, the Osmolar Gap can be affected by various factors including hyperlipidemia, hyperproteinemia, and the presence of multiple osmotically active substances.

Q5: How is calculated serum osmolality typically determined?
A: Calculated serum osmolality is often determined using the formula: 2×Na + Glucose/18 + BUN/2.8 (all values in conventional units).