1. What is the Serum Osmolality Formula?

The Serum Osmolality Formula estimates the concentration of particles in blood serum. It's calculated using sodium, glucose, and blood urea nitrogen (BUN) values to assess the body's water-electrolyte balance.

2. How Does the Calculator Work?

The calculator uses the Serum Osmolality formula:

Where:

• \( Na \) — Sodium concentration (mEq/L)
• \( Glucose \) — Glucose concentration (mg/dL)
• \( BUN \) — Blood Urea Nitrogen (mg/dL)

Explanation: The formula calculates the osmotic concentration in serum by accounting for the major osmotically active particles.

3. Importance of Serum Osmolality Calculation

Details: Serum osmolality measurement is crucial for evaluating fluid and electrolyte balance, diagnosing dehydration, monitoring diabetes treatment, and assessing renal function.

4. Using the Calculator

Tips: Enter sodium in mEq/L, glucose in mg/dL, and BUN in mg/dL. All values must be valid (sodium > 0, glucose and BUN ≥ 0).

5. Frequently Asked Questions (FAQ)

Q1: What is the normal range for serum osmolality?
A: Normal serum osmolality ranges from 275 to 295 mOsm/kg. Values outside this range may indicate various medical conditions.

Q2: When is serum osmolality testing indicated?
A: It's used when evaluating dehydration, hyponatremia, hypernatremia, diabetes insipidus, and suspected alcohol intoxication.

Q3: How does this formula differ from measured osmolality?
A: This calculated osmolality provides an estimate. Measured osmolality (by freezing point depression) is more accurate and includes all osmotically active particles.

Q4: What is the osmolar gap?
A: The difference between measured and calculated osmolality. A gap > 10 mOsm/kg suggests the presence of unmeasured osmotically active substances.

Q5: Can this formula be used for clinical decision making?
A: While useful for screening, clinical decisions should be based on measured osmolality and comprehensive clinical assessment.