Calculates the C-reactive protein to albumin ratio using matched laboratory units.
Overview
Calculates the C-reactive protein to albumin ratio using matched laboratory units.
Clinical Significance
Combines an inflammatory marker and a negative acute-phase protein. Published cut-offs vary substantially by disease and setting.
How It Is Calculated
- CAR = CRP (mg/L) / albumin (g/L).
Interpretation
- Combines an inflammatory marker and a negative acute-phase protein. Published cut-offs vary substantially by disease and setting.
Worked Example
Enter a clinically consistent set of values in the displayed units. MedicalC applies: CAR = CRP (mg/L) / albumin (g/L).
Limitations
- This tool does not establish a diagnosis or mandate treatment.
- Published cut-offs may vary between cohorts and measurement methods.
- Calculation precision cannot compensate for poor source data.
Clinical Pearls
- Trend the result over time where clinically appropriate.
- Record the source values and units alongside the calculated result.
Common Mistakes
- Using the wrong unit.
- Combining measurements obtained at different times.
- Applying a research-derived threshold as a universal treatment trigger.
Frequently Asked Questions
What does this calculator provide?
Calculates the C-reactive protein to albumin ratio using matched laboratory units.
Can this result be used alone?
No. It must be interpreted with clinical context and appropriate investigations.
What equation is used?
CAR = CRP (mg/L) / albumin (g/L).
What is the main limitation?
The result depends on valid inputs and may not be calibrated for every population or setting.
References
- Fairclough E et al. Evaluation of a modified early warning system for acute medical admissions. QJM. 2009. — Formula, physiological or validation reference.
Reviewed by: MedicalC Clinical Editorial Team
Last reviewed: July 2026