Phenytoin Free Fraction Adjustment Calculator

Adjusts phenytoin levels for hypoalbuminemia and renal failure using the Sheiner-Tozer equation, calculates phenytoin-equivalent doses for fosphenytoin conversion, and loading dose calculations.

Weight
Height
Clinical Guidance

BMI is a screening measure of body size, not a direct measure of body fat. The standard WHO categories are underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30).

BMI can overestimate body fat in athletes with high muscle mass and underestimate it in older adults with low muscle mass. Interpret it alongside waist circumference and clinical context rather than as a standalone diagnosis.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.
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How It Works

Adjusts phenytoin levels for hypoalbuminemia and renal failure using the Sheiner-Tozer equation, calculates phenytoin-equivalent doses for fosphenytoin conversion, and loading dose calculations

Each component has a specific meaning:

  • Sheiner-Tozer equation — The sheiner-tozer equation recorded for the scenario being assessed.
  • Calculates phenytoin-equivalent doses — The calculates phenytoin-equivalent doses recorded for the scenario being assessed.

Note: Interpret the phenytoin adjustment result against the thresholds and context described above.

How to Use

Enter the Sheiner-Tozer equation, calculates phenytoin-equivalent doses for the scenario you are assessing. Adjusts phenytoin levels for hypoalbuminemia and renal failure using the Sheiner-Tozer equation, calculates phenytoin-equivalent doses for fosphenytoin conversion, and loading dose calculations. Use the phenytoin adjustment result to inform your calculation.

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Frequently Asked Questions