FIB-4 With Reflex to Enhanced Liver Fibrosis (ELF)™

CPT: 84450; 84460; 85049
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Test Includes

Alanine aminotransferase (ALT/SGPT); aspartate aminotransferase (AST/SGOT); FIB-4 Index (by calculation); platelet count. If FIB-4 Index is >1.29, testing will reflex to Enhanced Liver Fibrosis (ELF™), performed at an additional charge.

Expected Turnaround Time

3 - 6 days

Related Documents

For more information, please review the literature below.

NAFLD-NASH Capabilities Brochure

AACE Guidelines in NAFLD White Paper

Specimen Requirements


Serum and whole blood


Serum: 2 mL divided into two tubes, 1 mL for initial testing and 1 mL for possible reflex

Whole blood: tube filled to capacity

Minimum Volume

Serum: 1.5 mL divided into two tubes, 0.75 mL for initial testing and 0.75 mL for possible reflex

Whole blood: tube filled to capacity


Gel-barrier tube or red-top tube and lavender-top (EDTA) tube


Serum: Separate from cells within 45 minutes of collection.

Whole blood: Invert EDTA tube immediately 8 to 10 times once tube is filled at the time of collection.

Storage Instructions

Serum sample for initial testing and whole blood can be stored at room temperature. Serum sample for possible reflex can be stored refrigerated a 2°C to 8°C for 72 hours.

Stability Requirements



Room temperature

Serum: 1 day; Whole blood: 1 day


Serum: 3 days; Whole blood: 3 days



Freeze/thaw cycles


Causes for Rejection

Serum: 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 anticoagulant other than EDTA

Test Details


According to the 2022 American Association of Clinical Endocrinology clinical practice guidelines, patients considered at high risk for Nonalcoholic Fatty Liver Disease (NAFLD) should be screened for NAFLD and advanced fibrosis using the following blood-based tests:

• To assess the risk of NAFLD with liver fibrosis, use liver fibrosis prediction calculations. The preferred noninvasive initial test is the FIB-4.

• Consider persons belonging to the “high risk” group who have an indeterminate or high FIB-4 score for further workup with an ELF test.

The FIB-4 index is reported to be a simple, accurate, non-invasive, and readily available laboratory test index that can help in the evaluation of patients with NAFLD for the presence of liver fibrosis, indication for liver biopsy, and other liver-related complications.

The Enhanced Liver Fibrosis (ELF™) blood test is a simple, accurate, non-invasive test that provides a simple, unitless numeric score that is generated via an algorithm for use in advanced liver fibrosis. It is indicated as a prognostic marker in conjunction with other laboratory findings and clinical assessments in patients with advanced fibrosis (F3 or F4) due to non-alcoholic steatohepatitis (NASH) to assess the likelihood of progression to cirrhosis and liver-related clinical events. Because ELF™ uses a blood sample rather than a biopsy, it can be used routinely for the same patient over time.


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.


AST and ALT: kinetic

Platelet Count: automated cell counter

ELF Reflex if performed: The ELF™ test consists of three fully automated, two-site sandwich immunoassays using direct chemiluminometric technology. The component assays use two monoclonal mouse antibodies: The first antibody is an acridinium ester-labeled antibody. The second antibody is a biotin-labeled antibody. The solid phase contains streptavidin-coated paramagnetic particles. The ELF™ score is derived from an algorithm that combines PIIINP, TIMP-1, and HA. ELF™ is a trademark of Siemens Healthcare Diagnostics.


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
Cusi K, Isaacs S, Barb D, et al. American Association of Clinical Endocrinology Clinical Practice Guideline for the Diagnosis and Management of Nonalcoholic Fatty Liver Disease in Primary Care and Endocrinology Clinical Settings: Co-Sponsored by the American Association for the Study of Liver Diseases (AASLD). Endocr Pract. 2022 May;28(5):528-562.35569886
Day J, Patel P, Parkes J, Rosenberg W. Derivation and performance of standardized Enhanced Liver Fibrosis (ELF) test thresholds for the detection and prognosis of liver fibrosis. J Appl Lab Med. 2019 Mar;3(5):815-826.31639756


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
402175 FIB-4 w/Reflex to ELF 001123 AST (SGOT) IU/L 1920-8
402175 FIB-4 w/Reflex to ELF 001545 ALT (SGPT) IU/L 1742-6
402175 FIB-4 w/Reflex to ELF 015172 Platelets x10E3/uL 777-3
402175 FIB-4 w/Reflex to ELF 011582 FIB-4 Index N/A
Reflex Table for FIB-4 Index
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 550659 Enhanced Liver Fibrosis (ELF) 550661 ELF(TM) Score 48795-9

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