**6. Laboratory testing**

then disappears once the disease disappears. Once acute HCV infection has established itself, around 85% of patients develop chronic infection, which is generally asymptomatic. In these patients, HCV RNA remains present and in approximately 75% of patients, alanine amino‐ transferases (ALT), and aspartate aminotransferases (AST) remain elevated at more than 1.5 times the upper normal limit. The course of chronic hepatitis C is variable, with vague, intermittent, and nonspecific symptoms of chronic fatigue and malaise, which usually present in less than 20% of patients. Extrahepatic manifestations of HCV, including glomerulonephritis and cryoglobulinemia, can develop in a small percentage of patients. The development of progressive liver injury, fibrosis, and cirrhosis can occur in 20% to 30% of chronically infected patients over a period of 20-30 years. In patients presenting with chronic hepatitis C, fibrosis progression is extremely variable over time and can be partially predicted based on the age of the patient at infection, disease duration, liver histologic activity and stage of fibrosis, and ALT profile. However, it is often difficult to predict clinical outcomes in individual cases. In patients who have developed cirrhosis, the 5-year risk of decompensation is between 15% and 20% and that of hepatocellular carcinoma around 10%. The relationship between virus load, HCV genotype, quasi-species variability, and progression of liver disease is controversial. Acquired infection after age 40 years, being male, excessive alcohol consumption, hepatitis B virus (HBV) or HIV coinfection, steatosis, and immunosuppressed state have all been identified as cofactors associated with progression of fibrosis and development of cirrhosis. Once cirrhosis develops, symptoms are more common, and the signs of end-stage liver disease can appear, manifesting themselves as jaundice, weakness, wasting, and gastrointestinal bleeding. The incidence of developing hepatocellular carcinoma is 2-5% per year in patients with hepatitis C-related cirrhosis. Thus, this important liver disease has protean manifestations but is often insidious and can often lead to end-stage liver disease that needs liver transplantation, despite the

The risk factors for the transmission of HCV infection vary substantially between countries and geographic regions. HCV is spread primarily by contact with blood and blood products. With the introduction in 1991 of routine blood screening for HCV antibodies and improve‐ ments in the test in mid-1992, transfusion-related hepatitis C has virtually disappeared. Illicit use of injectable drugs is currently the main source of HCV infections in most developed countries (e.g., Western Europe, US) and is becoming a major source of infection in transitional economy and developing countries, accounting for 40% or more of those infected. Of the estimated 16 million people in 148 countries who actively inject drugs, 10 million are infected with HCV [2,21,22]. In developing and transitional economy countries, the nosocomial transmission of new HCV infections is a major problem because of the reuse of contaminated or inadequately sterilized syringes and needles used in medical, paramedical, and dental procedures, with an estimated 2.3-4.7 million new infections occurring each year [2,23-25]. In patients on chronic hemodialysis, overall, the current prevalence of HCV is below 5% in most of Northern Europe, around 10% in most of Southern Europe and the US, but between 10%

presence of few overt symptoms and signs of illness [16-20].

**5. Risk factors**

82 Recent Advances in Liver Diseases and Surgery

#### **6.1. Serologic and molecular assays**

The test for anti-HCV is usually performed in the presence of an elevated ALT level and a positive history of risk factors for HCV infection, or physical findings suggest the presence of chronic liver disease. WHO recommends that HCV serology testing be performed on individ‐ uals who are part of a population with high HCV seroprevalence or who have a history of HCV risk exposure and/or behavior rather than at the time of presentation with symptomatic disease. The application of this recommendation will require taking into consideration which populations meet these criteria. In some countries with a high seroprevalence of HCV or a low level of infection control, HCV testing might be recommended for the general population. Clearly, this would have significant resource implications [1]. Diagnosis of HCV infection is based on the detection of anti-HCV antibodies by enzyme immunoassay and the detection of HCV RNA by a sensitive molecular method, ideally a real-time PCR assay. These assays have no role in the assessment of disease severity or its prognosis [32,33]. Genotyping is useful in epidemiological studies, and also in clinical management, for predicting the likelihood of response and determining the optimal duration of therapy. Several commercial assays are available to determine HCV genotypes using direct sequence analysis of the 5 noncoding region, which includes Trugene 5 NC HCV genotyping kit, reverse hybridization analysis using genotype-specific oligonucleotide probes located in the 5 noncoding region, INNO-LiPa HCV II, and Versant HCV Genotyping Assay 2.0 [34,35].

#### **6.2. Defining disease severity**

Laboratory tests that are commonly obtained following the initial diagnosis of chronic hepatitis C include liver enzymes and function tests, a complete blood cell count, tests for coinfection with HBV or HIV, tests for immunoglobulin G antibody to hepatitis A virus (anti-HAV) to determine if immunity is present or if vaccination is recommended, and antinuclear antibody to exclude coexistent autoimmune hepatitis.

Elevated blood levels of liver enzymes ALT and AST occur when the membrane of the liver cells is damaged and liver enzymes leak into the blood stream, thus indicating ongoing liver injury. The degree of elevation of liver enzymes present in the blood correlates with the severity of liver cell injury. However, blood levels of liver enzymes do not correlate with the degree or severity of hepatic fibrosis. The important tests that reflect liver synthetic function are serum bilirubin, albumin, and international normalized ratio (INR). Abnor‐ mal serum albumin, bilirubin, or prothrombin time may be seen in the setting of im‐ paired hepatic synthetic function. Some models used to evaluate liver disease severity are helpful for the assessment of liver function, for example, the model for end-stage liver disease (MELD). The MELD score was adopted by UNOS in 2002 for use in deceased donor liver allocation for adults with cirrhosis. MELD is a prospectively developed and validat‐ ed chronic liver disease severity scoring system that uses a patient's laboratory values for serum bilirubin, serum creatinine, and INR to predict a 3-month survival [36]. The MELD equation that is currently used by UNOS for prioritizing allocation of deceased donor livers for transplantation is as follows: MELD = 3.8\*loge(serum bilirubin [mg/dL]) + 11.2\*loge(INR) + 9.6\*loge(serum creatinine [mg/dL]) + 6.4. Patients with the combination of serum creati‐ nine ≤1 mg/dl, serum bilirubin ≤1 mg/dl, and INR ≤1 will receive the minimum score of 6 MELD points. In addition, UNOS has set an upper limit for the MELD score at 40 points. However, there is no need to go through the above time-consuming equation because several online tools are available for calculating the MELD score [37-39].
