Calculator

Inflammation Marker Interpreter

Enter whichever inflammatory labs you have. See where each one sits, what raises it besides inflammation, and what the combination suggests. Educational context, not a diagnosis.

Age (years)

Used for the age-adjusted ESR upper limit

Sex

ESR and ferritin reference ranges differ by sex

Male Female

hs-CRP (mg/L)

High-sensitivity C-reactive protein. Leave blank if not tested.

ESR (mm/hr)

Westergren erythrocyte sedimentation rate. Leave blank if not tested.

Ferritin (ng/mL)

Same as µg/L. Leave blank if not tested.

Fibrinogen (mg/dL)

Clauss method. Leave blank if not tested.

Context (check any that apply)

These change how the numbers should be read.

Infection, injury, or surgery in the past 4 weeks Known autoimmune or inflammatory condition Currently pregnant Taking a statin BMI 30 or above

Remember: a single measurement is a snapshot, not a verdict. hs-CRP can vary substantially week to week in the same person, and any recent cold, hard workout, or minor injury can move these numbers. Trends across repeat tests, interpreted by a clinician who knows your history, beat any one-off reading. This tool contextualizes lab values; it does not diagnose anything.

How this works

All four markers rise as part of the acute-phase response: tissue injury or infection triggers interleukin-6 release, which drives the liver to synthesize C-reactive protein, fibrinogen, and ferritin. But they move on very different clocks. CRP starts rising within about 6 hours, peaks around 48 hours, and has a plasma half-life near 19 hours, so it tracks acute events closely. Fibrinogen has a half-life of roughly 4 days, and because ESR is largely an indirect readout of plasma fibrinogen (fibrinogen makes red cells stack and settle faster), ESR rises and falls over days to weeks. That kinetic gap is why CRP and ESR can legitimately disagree, and why the combination is more informative than either alone (Lapic 2020 meta-analysis: pooled sensitivity 0.86 for CRP vs 0.78 for ESR in acute inflammation, higher when combined).

For hs-CRP, this tool applies the AHA/CDC bands from the Pearson 2003 statement: under 1 mg/L is lower relative cardiovascular risk, 1 to 3 mg/L average, above 3 mg/L higher. A value above 10 mg/L falls outside the cardiovascular framework entirely; the statement recommends discarding it as likely acute inflammation and repeating in about 2 weeks once well. The cardiovascular relevance of the 1 to 3 and over 3 bands has strengthened since 2003: in a 2023 pooled analysis of 31,245 statin-treated patients, residual inflammatory risk measured by hs-CRP predicted cardiovascular death and all-cause mortality more strongly than residual LDL cholesterol.

For ESR, the tool computes the widely used age-adjusted upper limit (Westergren method): age divided by 2 for men, and age plus 10 divided by 2 for women, since ESR drifts upward with normal aging.

Ferritin is the trickiest of the four because it plays two roles: it reflects total body iron stores, and it is simultaneously an acute-phase reactant. The 2018 British Society for Haematology guideline notes that roughly 90% of raised ferritins in practice are not iron overload; alcohol, liver disease, metabolic syndrome, and inflammation are far more common causes. The tool uses upper limits of about 300 ng/mL for men and 200 ng/mL for women, flags values above 1000 ng/mL as needing clinical workup, and points out that distinguishing overload from inflammation requires transferrin saturation, which this tool does not compute. Fibrinogen is scored against a typical 200 to 400 mg/dL reference interval.

The pattern logic then looks across whatever you entered: all normal, an isolated mild hs-CRP elevation (metabolic and cardiovascular context), several markers up together (an active inflammatory process worth clinical review), high ferritin with quiet CRP and ESR (think iron or metabolic causes rather than inflammation), or discordant results explained by kinetics or non-inflammatory ESR drivers.

References

Pearson TA, et al. Markers of inflammation and cardiovascular disease: application to clinical and public health practice: a statement for healthcare professionals from the Centers for Disease Control and Prevention and the American Heart Association. Circulation. 2003;107(3):499-511.

Ridker PM, et al. Inflammation and cholesterol as predictors of cardiovascular events among patients receiving statin therapy: a collaborative analysis of three randomised trials. Lancet. 2023;401(10384):1293-1301.

Cullis JO, et al. Investigation and management of a raised serum ferritin. Br J Haematol. 2018;181(3):331-340.

Lapic I, et al. Erythrocyte Sedimentation Rate and C-Reactive Protein in Acute Inflammation: Meta-Analysis of Diagnostic Accuracy Studies. Am J Clin Pathol. 2020;153(1):14-29.