Jelliffe Equation Explained
Estimating clearance without a urine collection.
What the Jelliffe equation estimates, including the non-steady-state form, and how it compares with Cockcroft-Gault.
Medically reviewed by Dr. Rishi Kumar Kafle, MBBS, MD, FASN. Last reviewed October 2026.
The Jelliffe equation estimates creatinine clearance from serum creatinine without a timed urine collection. Its main feature is a non-steady-state form designed for patients whose renal function is changing, which is the situation where Cockcroft-Gault is least reliable.
What the Equation Adds
The Jelliffe equation adds a way to estimate clearance when serum creatinine is not stable. Most clearance equations, including Cockcroft-Gault, assume a steady state: that serum creatinine is stable and reflects current kidney function. The Jelliffe method instead estimates clearance from the patient's creatinine production and the change in serum creatinine between two measurements, so a rising creatinine is read as falling clearance rather than as a fixed value.
| Axis | Jelliffe (non-steady-state) | Cockcroft-Gault |
|---|---|---|
| Steady state required | no | yes |
| Best setting | changing renal function / AKI | stable chronic function |
| Inputs | two creatinine values, body size, time interval | one creatinine, age, sex, weight |
| Output | creatinine clearance, mL/min | creatinine clearance, mL/min |
| Typical use | inpatient, dynamic dosing | routine renal drug dosing |
When It Helps
Jelliffe is most useful in acute kidney injury, when serum creatinine has not yet equilibrated and a single value would mislead. For example, if creatinine rises from 1.0 to 2.0 mg/dL over 24 hours, a steady-state equation would still report the clearance implied by an averaged value. The non-steady-state form recognises that true clearance has dropped sharply. For routine stable dosing, Cockcroft-Gault remains the practical standard; see CrCl vs eGFR.
Why a Steady State Matters
A steady state matters because steady-state equations assume that the rate creatinine is produced equals the rate it is cleared, so serum creatinine is stable and reflects current function. When that balance holds, a single creatinine value is an accurate snapshot. When it does not, because the kidneys have suddenly slowed, creatinine accumulates day by day, and a single value lags behind the true state of the kidney. Early in acute injury, serum creatinine may still look near-normal even though clearance has already collapsed, and a steady-state equation reading that low creatinine would falsely reassure. The Jelliffe non-steady-state method closes that gap by reading the trend in serum creatinine as well as the level.
What the Method Needs
Because it works from change over time, the Jelliffe non-steady-state form needs two serum creatinine measurements and the interval between them, plus an estimate of the patient's creatinine production from body size, age, and sex. From those, it infers how much clearance must have changed to produce the observed rise or fall. In exchange, it needs more data and is less convenient than Cockcroft-Gault, which needs only one creatinine and a few stable demographics.
How It Compares With Other Methods
The Jelliffe equation is one of several bedside equations, and each is tuned to a different situation. For stable outpatients, Cockcroft-Gault is the practical standard and the value most drug labels reference. For markedly obese patients, the Salazar-Corcoran equation addresses the overestimation that total body weight causes. For staging chronic kidney disease, the CKD-EPI 2021 eGFR is preferred. Jelliffe covers the remaining group: patients whose function is actively changing, where a fixed snapshot would mislead.
Strengths and Limitations
The Jelliffe equation's strength is tracking patients whose function is not stable, where other bedside equations fail. Its limitations are that it needs more than one creatinine measurement and an estimate of creatinine production, and it is less familiar to clinicians than Cockcroft-Gault, which is the value most drug labels reference. It is also an estimate, not a measured clearance, so in critically ill patients with very unstable physiology a measured collection or a renal specialist's judgement may still be needed. See creatinine clearance vs eGFR for how estimated clearance relates to true filtration.
A Practical Illustration
Suppose a patient is admitted with sepsis and the kidneys begin to fail. On day one the serum creatinine is 1.1 mg/dL; by day two it has climbed to 2.2 mg/dL. A steady-state equation reading the day-two value alone would report the clearance implied by 2.2 mg/dL. The patient's true clearance on day two is far lower, because creatinine is still accumulating and has not yet reached the level that the new, reduced filtration would eventually sustain. The non-steady-state method reads the day-one-to-day-two rise as evidence of that ongoing decline and reports a lower, more accurate clearance for dosing. The Jelliffe equation was built for this scenario.
Coefficient details for the live Jelliffe calculator are reviewed and approved; this page explains the method.