Laboratory Risk Indicator for Necrotizing Fasciitis (Wong et al., Crit Care Med 2004): 6 routine lab values, weighted 0–13, with risk bands and automatic unit conversion.
CRP ≥150 mg/L → 4 •
WBC <15 → 0, 15–25 → 1, >25 → 2 (×10⁹/L) •
Hb >13.5 → 0, 11–13.5 → 1, <11 → 2 (g/dL)Na ≥135 → 0, <135 → 2 (mmol/L) •
Creatinine >141 → 2 (µmol/L) •
Glucose >10 → 1 (mmol/L)All values convert automatically to the units used by Wong 2004 before scoring. Missing value = cannot compute.
| Score | Band | Interpretation (Wong 2004 / Hsiao 2020) |
|---|---|---|
| ≤ 5 | Low risk | Lower probability of NF in the original cohort — but ~10% of patients scoring <6 still had necrotizing fasciitis (WikEM journal-club summary). A low score does NOT exclude NF. |
| 6 – 7 | Intermediate risk | NF should be seriously considered; in the original study scores ≥6 fell in the 50–75% probability range. |
| ≥ 8 | High risk | Strongly predictive of NF in the original study (probability >75%); urgent surgical assessment indicated. |
Honest performance note. The headline figures (cutoff ≥6: sensitivity 89.9%, specificity 96.9%, PPV 92.0%, NPV 96.0%) come from Wong's developmental, retrospective cohort (89 biopsy-proven NF cases). Independent validations have been mixed: e.g. McGillicuddy et al. 2011 found sensitivity 86.3%, specificity 91.5% but PPV only 63.3%; systematic reviews report sensitivity ranging 36–83% across retrospective studies. LRINEC is a stratification aid — clinical suspicion drives the decision to operate.
Factors: creatinine mg/dL × 88.4 = µmol/L; glucose mg/dL ÷ 18 = mmol/L; CRP mg/dL × 10 = mg/L; hemoglobin g/L ÷ 10 = g/dL; WBC 1000/µL = 1 ×10⁹/L.
CRP 160 mg/L → 4 pts; WBC 18 ×10⁹/L → 1 pt; Hb 12.0 g/dL → 1 pt; Na 132 mmol/L → 2 pts; creatinine 1.9 mg/dL = 167.96 µmol/L → 2 pts; glucose 200 mg/dL = 11.11 mmol/L → 1 pt.
CRP 100 mg/L → 0; WBC 12 ×10⁹/L → 0; Hb 14.2 g/dL → 0; Na 138 mmol/L → 0; creatinine 1.1 mg/dL = 97.24 µmol/L → 0; glucose 150 mg/dL = 8.33 mmol/L → 0.
The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score is a clinical scoring system developed by Wong et al. (Crit Care Med 2004) to help distinguish necrotizing fasciitis from other severe soft-tissue infections. It combines six routine lab values — CRP, white blood cell count, hemoglobin, sodium, creatinine, and glucose — into a weighted score from 0 to 13.
Each lab value is assigned points: CRP ≥150 mg/L = 4; WBC <15 = 0, 15–25 = 1, >25 = 2 (×10⁹/L); hemoglobin >13.5 = 0, 11–13.5 = 1, <11 = 2 (g/dL); sodium ≥135 = 0, <135 = 2 (mmol/L); creatinine >141 = 2 (µmol/L); glucose >10 = 1 (mmol/L). Example: CRP 160 mg/L (4 pts), WBC 18 (1 pt), Hb 12.0 (1 pt), sodium 132 (2 pts), creatinine 1.9 mg/dL = 167.96 µmol/L (2 pts), glucose 200 mg/dL = 11.11 mmol/L (1 pt) → total 11/13.
Score ≤5 = low risk; 6–7 = intermediate risk (NF should be seriously considered); ≥8 = high risk (strongly predictive of NF in the original study). Per Hsiao et al. (PLoS One 2020), scores ≥6 fell in the 50–75% probability range and scores ≥8 above 75% in the original cohort.
In Wong's original developmental study, a cutoff of ≥6 had a positive predictive value of 92% and a negative predictive value of 96% (sensitivity 89.9%, specificity 96.9%). Independent validations have shown mixed results — some retrospective studies report much lower sensitivity (36–83%) — so the headline 92% PPV comes from the development cohort, not from later practice.
No. Published summaries note that roughly 10% of patients with scores below 6 still had necrotizing fasciitis. LRINEC is a risk-stratification aid, not a diagnosis. If the clinical picture is suspicious — severe pain out of proportion to findings, bullae, crepitus, systemic toxicity — surgical assessment must not wait for lab results.
Wong 2004 uses CRP mg/L, WBC ×10⁹/L, hemoglobin g/dL, sodium mmol/L, creatinine µmol/L, and glucose mmol/L. Convert: creatinine mg/dL × 88.4 = µmol/L (so 1.6 mg/dL = 141.44 µmol/L); glucose mg/dL ÷ 18 = mmol/L (so 180 mg/dL = 10 mmol/L); CRP mg/dL × 10 = mg/L; hemoglobin g/L ÷ 10 = g/dL. Mode 3 of this calculator does all of these automatically.
Necrotizing fasciitis is a rapidly spreading infection of the fascia and soft tissue. Even with modern care, global mortality is 19–30%. It is a surgical emergency: survival depends on early recognition, broad-spectrum antibiotics, and urgent surgical debridement. Never delay emergency care because of a calculator result.
No. The score was developed to aid risk stratification in patients already suspected of having a severe soft-tissue infection. It has not replaced clinical diagnosis, and prospective validations are limited. This tool is for education only and must not guide treatment decisions — those belong to the treating clinician, and suspected necrotizing fasciitis always warrants immediate emergency assessment.
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