LRINEC score for necrotizing fasciitis (Wong 2004)
The LRINEC score (Laboratory Risk Indicator for Necrotizing Fasciitis) adds points for six routine lab results: CRP, white cell count, hemoglobin, sodium, creatinine and glucose. The total runs from 0 to 13. Wong and colleagues published it in 2004 with a cut-off of 6, and Magent's calculator reports the score and whether it is at or above that cut-off.
Not a medical device. Not a diagnosis or dosing recommendation.
What is the LRINEC score?
Necrotizing fasciitis is a fast-spreading infection of the deeper soft tissues. Early on it can look like ordinary cellulitis or an abscess. Wong and colleagues set out a points table of routine labs to help tell necrotizing fasciitis apart from other soft tissue infections. That table is the LRINEC score.
Each of the six labs falls into a band, and each band is worth a fixed number of points. The points are added up. A total of 6 or more was the cut-off Wong 2004 proposed.
Magent's calculator takes the six lab values, converts units where needed, applies the Wong 2004 bands and returns the score, the maximum of 13, whether the score is at or above 6, and the points for each lab.
This page explains the table. It doesn't say what any score means for a particular person.
The LRINEC score table
lab band points
CRP (mg/L) ≥ 150 4
< 150 0
WBC (10^3/mm^3) < 15 0
15 to 25 1
> 25 2
hemoglobin (g/dL) > 13.5 0
11 to 13.5 1
< 11 2
sodium (mmol/L) < 135 2
≥ 135 0
creatinine (µmol/L) > 141 2
≤ 141 0
glucose (mmol/L) > 10 1
≤ 10 0
LRINEC = sum of the six rows maximum 13
at or above cut-off when LRINEC ≥ 6Exact expression the calculator uses:
LRINEC = CRP (>=150 mg/L → 4) + WBC 10^3/mm^3 (<15 → 0; 15-25 → 1; >25 → 2) + hemoglobin g/dL (>13.5 → 0; 11-13.5 → 1; <11 → 2) + sodium (<135 mmol/L → 2) + creatinine (>141 µmol/L → 2) + glucose (>10 mmol/L → 1); max 13; cutoff >=6Inputs
| Input | Meaning | Unit | Range |
|---|---|---|---|
crp_mg_l | C-reactive protein | mg/L | 0 to 500 |
wbc_k_ul | White cell count | 10^3/mm^3 (k/µL) | 0.01 to 500 |
wbc_ul | White cell count, alternative | cells/µL | 10 to 500000 |
hemoglobin_g_dl | Hemoglobin | g/dL | 3 to 22 |
sodium_mmol_l | Serum sodium | mmol/L | 110 to 160 |
creatinine_mg_dl | Creatinine | mg/dL | 0.1 to 20 |
creatinine_umol_l | Creatinine, alternative | µmol/L | 9 to 1768 |
glucose_mg_dl | Plasma glucose | mg/dL | 50 to 1000 |
glucose_mmol_l | Plasma glucose, alternative | mmol/L | 2.8 to 55.5 |
CRP, hemoglobin and sodium are always required. White cell count, creatinine and glucose each need one of their two unit forms.
How the calculation works
- Convert units. Creatinine in mg/dL is multiplied by 88.42 to give µmol/L. Glucose in mg/dL is divided by 18.0182 to give mmol/L. A white cell count in cells/µL is divided by 1000.
- Score each lab. CRP scores 4 or 0. White cell count and hemoglobin score 0, 1 or 2. Sodium and creatinine score 2 or 0. Glucose scores 1 or 0.
- Add the six rows. The total is between 0 and 13.
- Compare with the cut-off. The flag is true when the total is 6 or more.
CRP is the heaviest single row. With CRP at 150 mg/L or more, any other row worth 2 points brings the total to the cut-off.
Units
Creatinine's band is set in µmol/L (above 141), so a mg/dL value is converted first. In Magent's own reference cases, 1.6 mg/dL becomes about 141.5 µmol/L and scores 2, while 1.5 mg/dL becomes about 132.6 µmol/L and scores 0. Glucose's band is set in mmol/L (above 10). White cell count is in thousands per cubic millimetre, which is the same as 10^9/L.
Worked examples
These use Magent's own expected values for the calculator.
Example 1: every lab in its zero-point range
- CRP 20 mg/L, WBC 8, hemoglobin 14 g/dL, sodium 140 mmol/L, creatinine 1.0 mg/dL, glucose 90 mg/dL.
- Each lab sits in its zero-point band.
- LRINEC score 0. Below the cut-off.
Example 2: CRP at 150 mg/L, nothing else
- CRP 150 mg/L. The other labs are as in Example 1.
- CRP at 150 or more is worth 4 points. The rest score 0.
- LRINEC score 4. Below the cut-off of 6.
Example 3: CRP plus low sodium reaches the cut-off
- CRP 150 mg/L and sodium 134 mmol/L. The other labs are as in Example 1.
- CRP scores 4 and sodium below 135 scores 2.
- LRINEC score 6. At the cut-off, so the flag is true.
Example 4: every row at its top band
- CRP 150 mg/L, WBC 26, hemoglobin 10 g/dL, sodium 134 mmol/L, creatinine 1.6 mg/dL, glucose 11 mmol/L.
- Every lab is in its highest-scoring band.
- LRINEC score 13 out of a maximum of 13. At or above the cut-off.
History of the LRINEC score
Wong CH and colleagues published the score in Critical Care Medicine in 2004. As the paper's title says, the aim was a tool for telling necrotizing fasciitis apart from other soft tissue infections, using six routine labs. They proposed a total of 6 as the cut-off. Magent's calculator applies the Wong 2004 table as published and doesn't add a separate high band at 8.
When it's used
The score is worked out when a soft tissue infection is being assessed and the six labs are available from routine blood tests.
Where it's used
It is used in hospital settings where these blood tests are drawn, such as emergency departments and wards.
Who uses it
Clinicians read the lab results into the table. The calculator applies the bands, converts units and adds up the points.
Limits of the calculation
- The score uses lab values alone. It doesn't take in the examination, imaging or how the illness is changing.
- A score below 6 doesn't exclude disease. Wong later noted that about 10% of patients with a score below 6 still had necrotizing fasciitis.
- The calculator gives the score and the cut-off flag. It doesn't grade risk beyond that.
- This page doesn't say what to do with a result.
Clinical decisions belong to a qualified clinician who knows the patient.
How it differs from related calculators
- SIRS criteria count temperature, heart rate, breathing rate and white cell count. LRINEC is a lab table for soft tissue infection.
- SOFA scores six organ systems. LRINEC scores six labs against fixed bands.
- qSOFA uses three bedside signs and no labs.
Glossary
- Necrotizing fasciitis: a rapidly spreading infection of the deep soft tissues.
- CRP (C-reactive protein): a blood marker of inflammation.
- WBC: white blood cell count.
- Cut-off: the total at which Wong 2004 drew its line, here 6.
Common mistakes
- Using creatinine in mg/dL against the µmol/L band. Convert first. The band is above 141 µmol/L.
- Using glucose in mg/dL against the mmol/L band. The band is above 10 mmol/L.
- Adding a band at 8. Wong 2004 has a single cut-off at 6.
- Reading a low score as clearing the patient. The record notes that a score below 6 doesn't exclude disease.
- Scoring CRP in mg/dL. The CRP band is in mg/L.
Source
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(7):1535-1541. DOI: 10.1097/01.CCM.0000129486.35458.7D. PMID: 15241098
Frequently asked questions
What does LRINEC stand for?
Laboratory Risk Indicator for Necrotizing Fasciitis.
What is the LRINEC cut-off?
Wong 2004 used a score of 6 or more. The calculator flags a score at or above 6.
Does a score below 6 rule out necrotizing fasciitis?
No. The record notes that about 10% of patients with a score below 6 still had necrotizing fasciitis.
What is the maximum LRINEC score?
13, with every lab in its highest-scoring band.
Which units does the LRINEC score use?
CRP in mg/L, white cell count in 10^3/mm^3, hemoglobin in g/dL, sodium in mmol/L, creatinine in µmol/L and glucose in mmol/L. The calculator converts creatinine and glucose from mg/dL.