Clinical implications of serum hepatitis B virus RNA quantitation in untreated chronic hepatitis B virus-infected patients

Serum hepatitis B virus (HBV) RNA quantitation may be useful for managing untreated chronic HBV-infected patients, but its distribution characteristics and relationship to HBV DNA are unclear. A retrospective cohort including 149 untreated HBV-infected patients was divided into four clinical phenotypes: hepatitis B envelope antigen (HBeAg) positive with normal alanine transaminase (ALT; EPNA) or with elevated ALT (EPEA), HBeAg-negative with normal ALT (ENNA) or with elevated ALT (ENEA). Serum HBV RNA levels were quantified by a high-sensitivity real-time fluorescent quantitative PCR method and liver biopsy was performed in those with undetectable serum HBV DNA or RNA. The detectable serum HBV RNA levels (log₁₀ copies/mL) in EPNA, EPEA, ENNA, and ENEA were 6.02±1.48, 6.54±1.27, 2.51±0.78 and 3.54±1.25, respectively. The low level (< 2.0 log₁₀ copies/mL) comprised mainly of ENNA phenotype (76.9%), while the high level (> 6.0 log₁₀ copies/mL) was HBeAg-positive patients (98.1%). Serum HBV RNA level were significantly correlated with serum HBV DNA and HBsAg in HBeAg-positive phenotypes, but a correlation only with HBV DNA was observed in ENEA patients. Serum HBV DNA and RNA were both independent risk factors associated with elevated ALT in HBeAg-negative patients. Seven serum HBV DNA-undetectable but RNA-detectable patients underwent liver biopsy, showing moderate or severe liver inflammation. Varying serum HBV RNA levels can reflect natural disease phases in untreated HBV-infected patients, indicating that this biomarker could reflect liver inflammation in untreated HBeAg-negative patients as successfully as serum HBV DNA. Serum HBV RNA can complement clinical management strategies when serum HBV DNA is undetectable.