Fractional Excretion Of Calcium Calculator

Fractional Excretion of Calcium Equation:

\[ FE_{Ca} = \frac{(urine\ Ca / serum\ Ca)}{(urine\ Cr / serum\ Cr)} \times 100 \]

Urine Ca:

mg/dL

Serum Ca:

mg/dL

Urine Cr:

mg/dL

Serum Cr:

mg/dL

Fractional Excretion of Calcium (FE_Ca):

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1. What is Fractional Excretion of Calcium?

Fractional Excretion of Calcium (FE_Ca) is a calculation used to assess the kidney's handling of calcium. It represents the percentage of filtered calcium that is excreted in the urine, providing insight into calcium metabolism and renal function.

2. How Does the Calculator Work?

The calculator uses the Fractional Excretion of Calcium equation:

\[ FE_{Ca} = \frac{(urine\ Ca / serum\ Ca)}{(urine\ Cr / serum\ Cr)} \times 100 \]

Where:

\( urine\ Ca \) — Urine calcium concentration (mg/dL)
\( serum\ Ca \) — Serum calcium concentration (mg/dL)
\( urine\ Cr \) — Urine creatinine concentration (mg/dL)
\( serum\ Cr \) — Serum creatinine concentration (mg/dL)

Explanation: The equation compares the clearance of calcium to the clearance of creatinine, providing a ratio that reflects the fractional excretion of calcium.

3. Importance of FE_Ca Calculation

Details: FE_Ca is clinically useful in differentiating various causes of hypercalcemia and hypocalcemia, assessing renal calcium handling, and evaluating patients with kidney stones or renal tubular disorders.

4. Using the Calculator

Tips: Enter all values in mg/dL. Ensure all measurements are from simultaneous urine and serum samples for accurate results. All values must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the normal range for FE_Ca?
A: Normal FE_Ca is typically 1-2% in individuals with normal calcium homeostasis, but may vary based on dietary calcium intake and other factors.

Q2: When is FE_Ca particularly useful?
A: It's especially helpful in distinguishing between hypercalcemia due to hyperparathyroidism (usually <2%) and other causes (often >2%).

Q3: Are there limitations to this calculation?
A: Results can be affected by medications, volume status, and the timing of sample collection. It should be interpreted in clinical context.

Q4: How should samples be collected?
A: Serum and urine samples should be collected simultaneously, preferably from a 24-hour urine collection or spot urine with concurrent serum measurement.

Q5: Can FE_Ca be used in patients with renal impairment?
A: Yes, but interpretation may be more complex as values can be affected by the degree of renal dysfunction and other metabolic abnormalities.