LRINEC Score Calculator (Necrotizing Fasciitis Risk)
Calculate the LRINEC score for necrotizing soft tissue infection from CRP, white cells, hemoglobin, sodium, creatinine and glucose, in conventional or SI units, with low, intermediate or high risk.
How it works
CRP ≥ 150 mg/L: 4 · WBC 15–25 ×10⁹/L: 1, > 25: 2 · hemoglobin 11–13.5 g/dL: 1, < 11: 2 · sodium < 135 mmol/L: 2 · creatinine > 1.6 mg/dL (141 µmol/L): 2 · glucose > 180 mg/dL (10 mmol/L): 1. Total 0–13: ≤ 5 low risk (< 50%), 6–7 intermediate (50–75%), ≥ 8 high (> 75%).
The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score was derived by Wong and colleagues (Critical Care Medicine 2004) from routine blood tests in patients with severe soft tissue infection, to help distinguish necrotizing fasciitis from cellulitis or abscess. In the original study a score of 6 or more had a positive predictive value of 92% and a negative predictive value of 96%, but later studies found much lower sensitivity. A low score must never delay surgical exploration when the clinical picture — pain out of proportion, rapid spread, crepitus, skin necrosis or systemic toxicity — suggests necrotizing infection.
Worked example
A patient with a painful, swollen leg has CRP 160 mg/L (4), white cells 18 ×10⁹/L (1), hemoglobin 12.5 g/dL (1), sodium 136 mmol/L (0), creatinine 1.2 mg/dL (0) and glucose 150 mg/dL (0): LRINEC = 6 / 13 — intermediate risk (probability 50–75%).
Sources: Wong CH et al. The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections. Crit Care Med 2004;32:1535–1541 · Fernando SM et al. Necrotizing soft tissue infection: diagnostic accuracy of physical examination, imaging, and LRINEC score — a systematic review and meta-analysis. Ann Surg 2019
Frequently asked questions
What LRINEC score suggests necrotizing fasciitis?
In the original study, 6 or more raised suspicion and 8 or more was strongly predictive (over 75% probability). Scores of 5 or less were low risk, but necrotizing infection can still occur with a low score.
Can a low LRINEC score rule out necrotizing fasciitis?
No. Validation studies found the score misses a substantial share of cases. Clinical suspicion should lead to urgent surgical consultation and exploration regardless of the score.
What units does the LRINEC use?
The original paper used CRP in mg/L, white cells ×10³/mm³, hemoglobin in g/dL, sodium in mmol/L, creatinine in µmol/L and glucose in mmol/L. This calculator accepts conventional or SI units and converts.
Why is CRP worth 4 points?
In the derivation study, a CRP of 150 mg/L or more was the strongest independent predictor of necrotizing fasciitis, so it carries the most weight.
Related calculators
Clinical decision tool for education and for use by trained clinicians alongside clinical judgement — not a diagnosis and not a substitute for medical assessment. Scores and cut-offs come from the cited validation studies and may not apply to every patient; follow local protocols.