Evaluating hepatic fibrosis in chronic hepatitis C patients
Diagnosing fibrosis in carriers of chronic hepatitis B virus
Evaluating hepatic fibrosis in co-infected HIV carriers
Providing access to new-generation noninterferon treatment for hepatitis
Evaluating fibrosis in patients suffering from metabolic conditions (nonalcoholic fatty liver disease) and patients who consume excess alcohol
This test is a patented test algorithm developed by BioPredictive. FibroTest combines 5 standard biomarkers (gamma-glutamyltransferase, total bilirubin, alpha-2-macroglobulin, apolipoprotein A1, and haptoglobin). The ActiTest adds a marker for inflammatory activity (alanine aminotransferase: ALT). These markers are weighted depending on the patient's age and gender
Testing is compliant with BioPredictive's technical recommendations and approvals
Preferred: Serum Gel (SST)
Acceptable: Red Top
Specimen Collection / Processing Instructions
Centrifuge and aliquot within 2 hours of collection
Centrifuged serum must be light protected within 4 hours of collection. It is acceptable to draw the blood and then protect it from light after centrifugation as long as it is within 4 hours of collection.
Age and sex are required
Refrigerated (preferred): 7 days
Frozen: 14 days
Ambient: 24 hours
Unacceptable Specimen Conditions
Patients < 2 years of age
Defer the test in transient situations that could modify the components of FibroTest-ActiTest, such as:
Acute hemolysis, which could decrease haptoglobin and increase unconjugated bilirubin
Acute hepatitis, whether drug-induced, viral (superinfection by hepatitis A virus: HAV, hepatitis B virus: HBV, EpsteinBarr virus: EBV), or autoimmune. Massive hepatic necrosis leads to a large increase of transaminases and total bilirubin
Acute inflammation, as with concomitant bacterial or acute viral infection: bronchopulmonary or urinary tract infection. The large increase of haptoglobin can lead to false-negative results
Extrahepatic cholestasis, such as gallstones
The advice of a liver disease specialist should be sought for interpretation in chronic states in which the components of the test could be modified, such as chronic hemolysis, particularly in patients with a cardiac valvular prosthesis; Gilbert disease; protease inhibitors used in HIV treatment, which can increase unconjugated bilirubin (Indinavir, Atazanavir); or gamma glutamyltransferase (GGT) and alanine aminotransferase (Ritonavir)
The interpretation of FibroTest has been validated in renal transplant patients. In patients with renal insufficiency or who are on dialysis, FibroTest had an acceptable diagnostic value, though lower than in transplanted patients
As a general rule, isolated extreme values of 1 of the 6 components should signal caution in interpreting the results, particularly in the following cases:
Haptoglobin below 12 mg/dL, in which hemolysis or anhaptoglobinemia (more frequent in western African patients) must be ruled out.
Haptoglobin above 320 mg/dL, in which acute inflammation must be ruled out.
Transaminases above 622 IU/L, in which acute hepatitis must be ruled out
Bilirubin above 1.75 mg/dL and GGT below 50 IU/L, in which Gilbert syndrome must be suspected
Alpha2-macroglobulin above 590 mg/dL
In case of discordance between a biopsy result and a FibroTest result, it is advisable to seek the advice of a liver disease specialist
Haptoglobin is an acute-phase reactant and increases with inflammation or tissue necrosis. Low haptoglobin is normal for the first 3 to 6 months of life; testing is not performed on patients younger than 2 years-old per BioPredictive
GGT activity is inducible by drugs such as phenytoin and phenobarbital and, therefore, elevations should not be considered indicative of liver disease until drug use is ruled out. Elevations are also seen after ingestion of alcoholic beverages. In very rare cases, gammopathy, in particular, type IgM (Waldenstrom macroglobinemia) may cause unreliable results
Bilirubin specimens should be protected from light and analyzed as soon as possible. Grossly hemolyzed specimens should be rejected because hemoglobin inhibits the diazo reaction and falsely decreased results may be seen. Compounds that compete for binding sites on serum albumin contribute to lower serum bilirubin levels (eg, penicillin, sulfisoxazole, acetylsalicylic acid).
INTF: Algorithm and interpretation provided through BioPredictive
APOAF: Automated Turbidimetric Immunoassay
ALTF: Photometric Rate, L-Alanine with Pyridoxal-5-Phosphate
*Boundary values can apply to 2 stages based on rounding. For example, a FibroTest score of 0.305 will round up to 0.31 and be staged F1. A FibroTest score of 0.314 will round down to 0.31 and be staged F1-F2.
*Boundary values can apply to 2 grades based on rounding. For example, an ActiTest score of 0.285 will round up to 0.29 and be graded A0-A1. An ActiTest score of 0.294 will round down to 0.29 be graded A1.