Osmolality Calculator

Calculate Serum Osmolality

Enter the required values to calculate serum osmolality.

Results

Calculated Osmolality: --

Data Source and Methodology

All calculations are based rigorously on the formulas and data provided by the authoritative source: MDCalc.

The Formula Explained

The serum osmolality is calculated using the formula:

Osmolality (mOsm/kg) = 2 × [Na+] + [Glucose]/18 + [BUN]/2.8

Glossary of Terms

How It Works: A Step-by-Step Example

Suppose a patient has [Na+] = 140 mmol/L, [Glucose] = 90 mg/dL, and [BUN] = 14 mg/dL. The osmolality would be calculated as:

Osmolality = 2 × 140 + 90/18 + 14/2.8 = 280 + 5 + 5 = 290 mOsm/kg

Frequently Asked Questions (FAQ)

What is serum osmolality?

Serum osmolality is a measure of the solute concentration in blood.

Why is osmolality important?

Osmolality helps assess the body's water-electrolyte balance.

How frequently should osmolality be checked?

It depends on clinical circumstances, often checked in cases of dehydration or electrolyte imbalance.

What affects serum osmolality?

Factors include sodium, glucose, and urea levels.

Can I calculate osmolality manually?

Yes, using the formula provided above.

Tool developed by Ugo Candido. Content verified by the CalcDomain Expert Team.
Last reviewed for accuracy on: October 15, 2023.

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