FIB-4

CPT: 84450; 84460; 85049
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Synonyms

  • Cirrhosis
  • Liver Fibrosis
  • NAFLD
  • NASH

Expected Turnaround Time

Within 1 day


Related Documents


Specimen Requirements


Specimen

Serum (preferred) or plasma and whole blood


Volume

1 mL (serum or plasma); fill tube to capacity (whole blood)


Minimum Volume

0.5 mL (serum or plasma); 0.5 mL (whole blood)


Container

Gel-barrier tube or red-top tube or green-top (heparin) tube or lavender-top (EDTA) tube (plasma), and a separate lavender-top (EDTA) tube (whole blood)


Collection

Separate serum or plasma from cells within 45 minutes of collection; invert EDTA tube immediately 8 to 10 times once tube is filled at time of collection.


Stability Requirements

Temperature

Period

Room temperature

1 day (stability determined by manufacturer or literature reference)

Refrigerated

3 days (stability determined by manufacturer or literature reference)

Frozen

Unstable (stability determined by manufacturer or literature reference)

Freeze/thaw cycles

Unstable (stability determined by manufacturer or literature reference)


Causes for Rejection

Serum/plasma: Gross hemolysis; improper labeling

Whole blood: Hemolysis; clotted specimen, tube not filled with minimum volume; improper labeling; transfer tubes with whole blood; specimen diluted or contaminated with IV fluid; specimen received with plasma removed; specimen collected in any coagulant other than EDTA


Test Details


Use

FIB-4 index is reported to be a simple, accurate, non-invasive, and readily available laboratory test index that can help in evaluation of patients with HCV and Non-Alcoholic Fatty Liver Disease (NAFLD) for the presence of liver fibrosis indication for liver biopsy, and other liver-related complications. It was also reported to be concordant with FibroSure test results.


Limitations

Clumping may cause false low count. Platelet satellitism around neutrophils will cause a pseudothrombocytopenia. RBC or WBC fragments including fragmented fragile leukemic cells and neutrophil pseudoplatelets may cause falsely elevated counts.


Methodology

AST and ALT: Kinetic

Platelet Count: Automated cell counter


Reference Interval

0 – 1.29: low risk for advanced liver fibrosis

1.30 – 2.67: Indeterminate risk for advanced liver fibrosis

>2.67: high risk for advanced fibrosis and for developing of other liver-related events


Additional Information

The FIB-4 index value is calculated using the 4 parameters formula:

FIB-4 = [Age(Years) x AST (IU/L)] / [Platelets (10E3/L) x ALT^.5 (IU/L)]

The FIB-4 index was reported in a study of patients with HCV infection to correctly identify patients with severe fibrosis (METAVIR F3-F4) with area under the ROC curve of 0.85. A FIB-4 index of less than 1.45 had a negative predictive value of 94.7% to exclude extensive fibrosis (F3-F4) with a sensitivity of 74.3% and a specificity of 80.1%. A FIB-4 index of greater than 3.25 had a positive predictive value of 82.1% to confirm the existence of significant fibrosis (F3-F4) with a specificity of 98.2% and a sensitivity of 37.6%. In the same study, FIB-4 index was in agreement with FibroTest (known in the US as FibroSure) test results of 92.1% for exclusion of severe fibrosis (F3-F4) using a cutoff of less than 1.45, and agreement of 76.0% for detection of severe fibrosis (F3-F4) using a cutoff of greater than 3.25.

In more recent studies of patients with NAFLD, FIB-4 index was reported to have area under ROC curve of 0.802 for prediction of advanced fibrosis (F3-F4)using slightly different cutoffs of 1.30 and 2.67. A negative predictive value for the absence of advanced fibrosis at a cutoff of 1.30 was 83% and a positive predictive value for the presence of advanced fibrosis and hazard ratio for developing liver realated events at a cutoff of 2.67 was 80% and 14.6 respectively. A liver biopsy had been appropriately avoided in 54% of cases.


References

Angulo P, Bugianesi E, Bjornsson ES, et al. Simple noninvasive systems predict long-term outcomes of patients with nonalcoholic fatty liver disease. Gastroenterology. 2013 Oct;145(4):782-789.e4.23860502
Shah AG, Lydecker A, Murray K, et al. Comparison of noninvasive markers of fibrosis in patients with nonalcoholic fatty liver disease. Clin Gastroenterol Hepatol. 2009 Oct;7(10):1104-1112.19523535
Vallet-Pichard A, Mallet V, Nalpas B, et al. FIB-4: an inexpensive and accurate marker of liver fibrosis in HCV infection. Comparison with liver biopsy and fibrotest. Hepatology. 2007 Jul;46(1):32-36.17567829

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
403604 FIB-4 001123 AST (SGOT) IU/L 1920-8
403604 FIB-4 001545 ALT (SGPT) IU/L 1742-6
403604 FIB-4 015172 Platelets x10E3/uL 777-3
403604 FIB-4 011582 FIB-4 Index N/A

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