Lithium pharmacokinetic calculator

Lithium Level Estimator

Estimate a future steady-state lithium level from an early level or from a one-time dose change.

For psychiatrists and other psychiatric providers. Use as clinical decision support only; confirm with repeat lithium levels and clinical judgment.

Safety first

Not a prescription or substitute for clinical judgment

This tool provides estimates for licensed clinicians. It does not diagnose, treat, prescribe, or replace independent review of the patient, lab timing, formulation, renal function, sodium and fluid status, pregnancy risk, adherence, toxicity symptoms, or interacting medications.

No patient data is stored by this static calculator. You are responsible for verifying inputs, interpreting results, choosing therapy, monitoring safety, and complying with your local standard of care.

Step 1

Choose The Situation

New start

Early Level After Starting Lithium

mEq/L
mg

Dose history

Individual Doses Before Level

Enter only doses already taken before the blood draw.

mEq/L

Step 2

Estimate

24 h model
Estimated steady-state lithium level ? --
--
--

Range uses lithium half-lives from 18 to 36 hours. The main estimate uses 24 hours.

Regimen for desired level ? -- --
Blood draw timing -- --

Range detail

Why The Range Exists

Fast clearance 18 hour half-life --
Typical estimate 24 hour half-life --
Slow clearance 36 hour half-life --

Clinical guardrails

Timing, Formulation, And References

Dose change model

Use when the patient was already at steady state and you want a proportional estimate after one regimen change. It assumes comparable adherence, formulation, renal function, and sampling convention.

New start model

Use when lithium was newly initiated and a level was drawn before steady state. Enter the actual doses before the blood draw; formulation matters most when the draw is soon after a dose.

Confirm before acting

This tool estimates a dose, not a prescription. Recheck levels after changes and account for renal function, fluid and sodium status, adherence, toxicity symptoms, pregnancy risk, and interacting drugs.

Clinical utility

Lithium level calculator for psychiatric clinicians

This lithium level calculator helps psychiatrists and other psychiatric providers estimate where a lithium level may land before a patient has fully reached steady state. It supports two common workflows: new lithium initiation with an early lithium level, and a dose change from a known steady-state lithium level.

1. Choose the workflow New start for early levels; dose change for a stable patient whose regimen changed once.
2. Enter timing carefully For new starts, dose times and blood draw timing are central to the estimate.
3. Confirm clinically Use the estimate to plan monitoring and discussion, then confirm with follow-up levels.