Blood Urea Nitrogen Using Calculated Serum Osmolality Calculator

Blood Urea Nitrogen Formula:

\[ BUN = 2.8 \times ((Oserum) - (2 \times [Na]serum) - (Gserum/18)) \]

Calculated Serum Osmolality (Oserum):

mol/kg

Serum Sodium ([Na]serum):

mol/m³

Serum Glucose (Gserum):

kg/m³

Blood Urea Nitrogen (BUN):

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1. What is Blood Urea Nitrogen?

Blood Urea Nitrogen is a serum byproduct of protein metabolism. It is one of the oldest prognostic biomarkers in heart failure and provides important information about kidney function and protein metabolism.

2. How Does the Calculator Work?

The calculator uses the BUN formula:

\[ BUN = 2.8 \times ((Oserum) - (2 \times [Na]serum) - (Gserum/18)) \]

Where:

\( Oserum \) — Calculated Serum Osmolality (mol/kg)
\( [Na]serum \) — Serum Sodium concentration (mol/m³)
\( Gserum \) — Serum Glucose concentration (kg/m³)

Explanation: This formula calculates Blood Urea Nitrogen based on the relationship between serum osmolality, sodium levels, and glucose concentration.

3. Importance of BUN Calculation

Details: BUN measurement is crucial for assessing kidney function, monitoring protein metabolism, and evaluating hydration status. It's commonly used in the diagnosis and management of renal diseases and heart failure.

4. Using the Calculator

Tips: Enter calculated serum osmolality in mol/kg, serum sodium in mol/m³, and serum glucose in kg/m³. All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the normal range for BUN?
A: Normal BUN levels typically range between 7-20 mg/dL (2.5-7.1 mmol/L), though this can vary by laboratory and individual factors.

Q2: Why is BUN important in kidney function assessment?
A: BUN levels increase when kidney function declines because the kidneys are less able to filter urea from the blood for excretion in urine.

Q3: What factors can affect BUN levels besides kidney function?
A: High protein diet, dehydration, gastrointestinal bleeding, liver disease, and certain medications can affect BUN levels.

Q4: How does this calculation differ from direct BUN measurement?
A: This formula provides an estimated BUN value based on other serum parameters, while direct measurement provides an actual laboratory value.

Q5: When is this calculation method particularly useful?
A: This method can be useful when direct BUN measurement is unavailable or when verifying the consistency of laboratory results.