Renal
Creatinine
Creatinine is a waste product of muscle metabolism cleared from the blood almost entirely by the kidneys, so its concentration is a core marker of renal filtration. Point-of-care testing delivers a rapid whole-blood result, often alongside a calculated estimated glomerular filtration rate, to support decisions at the bedside or in clinic.
Why it is measured
It is measured to screen for and monitor kidney function, to assess risk before contrast-enhanced imaging, and to guide renal dose adjustment of medicines. A rising creatinine generally reflects reduced glomerular filtration.
| Typical range | Indicative adult serum or plasma creatinine is approximately 60 to 110 micromol/L (about 0.7 to 1.3 mg/dL), with women usually lower than men. Values vary with analytical method, age, sex and muscle mass, so always apply the range stated by the issuing device or laboratory. |
|---|---|
| Sample | Whole blood (capillary fingerstick or venous lithium-heparin), serum or plasma, depending on the platform. Handheld creatinine meters typically use a small fingerstick capillary sample, while cartridge and rotor systems accept lithium-heparin whole blood, serum or plasma. |
| Turnaround | Approximately 30 seconds to 2 minutes at the point of care, depending on the device. |
Point of care devices that report it
- Abbott i-STAT 1 and i-STAT Alinity (CREA cartridge; the i-STAT Alinity additionally calculates eGFR on the device)
- Nova Biomedical StatSensor and StatSensor Xpress Creatinine/eGFR meters
- Nova Biomedical Nova Max Pro Creatinine/eGFR meter
- Abbott (Abaxis) Piccolo Xpress general chemistry analyser (creatinine reported on the Renal Function and metabolic reagent discs)
- Siemens Healthineers epoc Blood Analysis System (BGEM test card, with calculated eGFR)
Questions, answered
Can point-of-care creatinine be used to calculate eGFR?
Yes. Several point-of-care creatinine devices automatically calculate an estimated glomerular filtration rate from the measured creatinine using equations such as CKD-EPI, MDRD or Cockcroft-Gault. The calculation depends on correct patient demographics, so operators should confirm that age and sex are entered accurately. This is an operational note, not a basis for interpreting an individual result.
Why might a point-of-care creatinine differ from the central laboratory value?
Differences can arise from the measurement chemistry (for example enzymatic versus Jaffe methods), sample type, calibration and traceability, and known interferences. For consistent trending it is good practice to compare methods locally and, where possible, follow a patient on a single platform rather than mixing results across analysers.
What are common operational uses of rapid creatinine testing?
Typical uses include checking renal function before contrast-enhanced imaging or cardiac catheterisation, supporting medication dosing decisions, and helping triage in emergency or community settings. The fast turnaround can reduce delays, while definitive diagnosis and management remain a clinical decision supported by full assessment.