When use the 0.1 factor?

Typically when creatinine clearance is below 20 mL/min.

Corrected Phenytoin

Neurology Critical Care General Medicine

Medical context

Adjust total phenytoin concentration for hypoalbuminemia using the Sheiner–Tozer equation.

Neurology and acute care teams combine scores with imaging and serial neurologic exams.

This page explains the Phenytoin formula, how to interpret the output, known limitations, and peer-reviewed references so you can verify results against primary sources and local protocols.

It is grouped under Neurology because coma scales and neurologic assessment scores.

How to use this calculator

Enter the values requested by the Phenytoin calculator using the units shown beside each field.
Review the calculated result and read the interpretation section before acting on the output.
Check limitations and references if the result will change management, dosing, or disposition.
Use the related calculators section when you need supporting values (for example electrolytes, weight, or complementary risk scores).

Calculator

Measured phenytoin (µg/mL)Albumin (g/dL)CrCl (mL/min)Uses 0.1 factor if <20

Result

16.7 µg/mL

Sheiner–Tozer corrected phenytoin

Using albumin factor 0.2 (renal CrCl <20 uses 0.1).

Educational use only. Confirm results with clinical judgment, primary sources, and local protocols. Not a substitute for professional medical advice. Full disclaimer.

Formula

Corrected = measured / [(0.2 or 0.1)×albumin + 0.1]. Use 0.1 when CrCl <20.

Interpretation

Compare corrected level to usual therapeutic range (~10–20 µg/mL) and clinical effect.

Limitations

Free phenytoin levels are preferred when available. Equations are estimates.

Frequently asked questions

When use the 0.1 factor?: Typically when creatinine clearance is below 20 mL/min.
Is the Phenytoin result enough to make a treatment decision?: No. Calculators support medical decision-making but do not replace examination, shared decision-making, institutional protocols, or consultant input when stakes are high.
Does Calcmedical store the values I type in?: Inputs are processed in your browser for this session. We do not ask for patient names or medical record numbers. See our privacy policy for hosting and analytics details.

References

Sheiner–Tozer phenytoin correction