Among the primary anti-hepatitis B virus medications, entecavir (ETV) and tenofovir alafenamide (TAF) are extensively utilized for their high efficacy, minimal side effects, and favorable cost-effectiveness ratios. During prolonged antiviral therapy, the clinical response is frequently indicated by the impact on hepatitis B virus DNA (HBV-DNA) levels. Per the guidelines of the American Association for the Study of Liver Diseases (AASLD), HBV-DNA levels below 2000 IU/mL are classified as low viremia. A low viral load is correlated with a heightened risk of liver cancer, particularly in individuals with cirrhosis[8].In this investigation, among renal tubular index abnormalities patients with suboptimal viral response to ETV, those who either persisted with ETV or transitioned to TAF therapy for 24 weeks exhibited notable differences. Specifically, among patients who continued ETV, there were 2 instances of HBV-DNA positivity and 6 cases of low viral load. Conversely, in the group that switched to TAF, there were no cases of positivity and 5 instances of low viral load. Although the rates of HBeAg seroconversion did not differ significantly between the two treatments (ETV: 67.74%, TAF: 72.58%), TAF demonstrated a marginally higher seroconversion rate. Should future studies include a larger sample size, additional evidence may emerge. TAF appears to offer a higher rate of complete viral response compared to ETV, and for chronic hepatitis B patients with a poor response to long-term ETV treatment, switching to TAF enhances viral response efficiency.Consequently, for individuals suffering from chronic hepatitis B who have experienced kidney tubular injury and exhibit a low viral load as a result of prolonged exposure to ETV, transitioning to TAF therapy may represent a beneficial therapeutic strategy. The hepatitis B virus is a significant contributor to liver cirrhosis, a condition that arises from recurrent liver damage and subsequent healing processes, which trigger an overproduction of collagen and alterations in the extracellular matrix by hepatic stellate cells[9].In this study, we assessed the extent of liver fibrosis, also known as liver stiffness, in hepatitis B patients by employing transient elastography (TE), a technique grounded in ultrasound technology. It is important to note that the liver stiffness index may be influenced by various factors, including postprandial fullness, inflammation, passive venous congestion, portal hypertension, and biliary obstruction[10].In this study, patients with clear hepatitis B cirrhosis and liver dysfunction were excluded. The findings suggest a significant disparity in the extent of liver fibrosis between the group that continued ETV treatment and the group that switched to TAF treatment after 24 weeks, prior to propensity score matching (PSM). Median values indicate that the liver fibrosis indicators for the TAF group are lower. Might this imply that TAF is more effective in improving liver fibrosis than ETV? After accounting for confounding variables, no significant statistical disparity was observed in the data comparison and their deviations from baseline between the two groups at the 24-week mark. This could be attributed to the fact that, prior to controlling for these variables, the baseline values for the ETV group were higher, resulting in a skewed difference. Additionally, all liver fibrosis indicators for the patients in this study fell within the normal range, which might explain why TAF and ETV had minimal impact on them. Should patients with hepatitis B cirrhosis be included in future studies to monitor the effects of these two drugs on their liver fibrosis indicators, it is possible that distinct effects would become apparent. Furthermore, ultrasound-based elastography can be influenced by numerous unpredictable factors. To achieve a comprehensive evaluation and validation, it would be advisable to incorporate additional indicators such as liver color Doppler ultrasound, portal vein pressure, and blood liver fibrosis tests in subsequent analyses.
Reports indicate that nucleoside analogues can induce Fanconi syndrome, characterized by varying levels of dysfunction in the proximal renal tubules. Symptoms include hypophosphatemia, hypouricemia, aminoaciduria, and glycosuria. Hypophosphatemia, in particular, may result in impaired bone mineralization, osteomalacia, and an increased risk of fractures[11, 12]. Consequently, when it comes to kidney injury induced by nucleoside analogues, the primary damage is inflicted upon the renal tubules. Hence, indicators that monitor renal tubular injury should exhibit greater sensitivity than eGFR. In this research, the serum phosphorus levels at week 24 exhibited a significant difference when compared to the baseline values for both the ETV group and the TAF switch group. The ETV group demonstrated an upward trend in variation, whereas TAF continued to decline. This result may be attributed to factors including diet, gastrointestinal absorption, renal absorption, and phosphate transport. Therefore, relying exclusively on blood phosphorus levels to assess renal function remains questionable. For future investigations, it is advisable to incorporate comprehensive evaluation indicators such as urinary phosphorus, urinary microalbumin, and the urinary microalbumin-to-creatinine ratio.
Urine α1-MG is a protein with a low molecular weight of 27 kDa, initially identified over half a century ago. In individuals with healthy kidneys, α1-MG protein readily traverses the glomerular membrane, with nearly 99% subsequently being reabsorbed and metabolized by the cells of the proximal tubule[13], consequently, an elevation in urinary α1-MG serves as an early indicator of renal impairment, predominantly affecting the proximal renal tubules. Its notable stability within urine has led to its adoption as a marker for tubular dysfunction, setting it apart from other markers of the tubules[14]. Urine RBP and urine β2-MG are also biomarkers of renal tubular dysfunction, with their low molecular weights being 21 kDa and 11 kDa, respectively,They can also be freely filtered by the glomerulus and almost completely reabsorbed by the proximal tubule[15]. NAG, a lysosomal hydrolase with a molecular weight of 150 kDa, is exclusively secreted into the urine by damaged proximal renal tubular cells. The increase in its levels indicates damage to the tubular structure[16]. In summary, this study employed urinary biomarkers α1-MG, β2-MG, NAG, and RBP to evaluate early tubular injury. Following 24 weeks of treatment, the TAF group exhibited notably reduced levels of urinary α1-MG, β2-MG, and NAG compared to the ETV group. However, no significant difference in urinary RBP levels was observed between the two groups. Additionally, after 24 weeks, there were no significant differences in renal tubular indicators or estimated Glomerular Filtration Rate (eGFR) between the two groups. This could be attributed to the fact that the study primarily focused on outcomes related to early tubular injury, whereas eGFR predominantly indicates glomerular damage. After 24 weeks, renal tubular indicators remained statistically similar between the two groups, potentially due to baseline disparities in renal tubular indicator levels, which undermined the statistical significance of the results. Upon data adjustment, a clear and significant difference in the variation of three renal tubular indicators became evident, with the TAF group demonstrating a more pronounced advantage in the reversal of renal tubular injury.In current research, urinary RBP primarily functions as a significant indicator for the prediction of diabetic nephropathy[17]. However, this study involved patients who had already been screened out for renal dysfunction and underlying diseases associated with hepatitis B, hence no significant difference was observed between the two groups.