Evaluation of renal toxicity in patients with chronic hepatitis b using tenofovir disoproxil fumarate

HBV infection is a global public health problem. HBsAg seroprevalence ranges from 2 percent to 7 percent in Turkey. Antiviral treatment should be initiated for patients with clinical indications for chronic HBV. Tenofovir is an acyclic nucleotide analog that can be used to treat HBV infection. The use of tenofovir disoproxil fumarate (TDF) has been associated with some side effects on renal function. The aim of this retrospective study was to evaluate the real-life data of the effect of TDF on renal toxicity and to contribute to the strategy of follow-up. One hundred and twenty eight patients were included into the study and their data were analyzed retrospectively. We evaluated the reasons for discontinuing or changing the medication and the course of HBV DNA levels throughout the therapy. Of the 128 patients a second cohort of 58 patients who completed a 36 month follow up period were examined in terms of levels of timedependent changes in creatinine, estimated GFR (CKD-EPI), BUN, calcium and phosphorus. Repeated Measurements ANOVA was used for the analysis of time dependent variables. P values less than 0.05 were considered statistically significant. HBV DNA negativity was observed to a lesser extent in patients with high initial HBV DNA levels and HBV DNA negativity was relatively late in these patients. No significant changes were observed in serum creatinine and estimated GFR (CKD-EPI) levels (p= 0.20 and p= 0.07, respectively). There was a significant decrease in the estimated GFR (CKD-EPI) levels measured in the first month compared with baseline levels (p=0,045). BUN levels were significantly increased (p<0,01). The increase in BUN levels in hypertensive patients was significantly higher than non-hypertensive patients (p=0,02). No significant changes were observed in serum calcium levels (p=0,40). Serum phosphorus levels decreased significantly during the follow-up period (p<0,01). TDF is a generally safe and well tolerated agent used in the treatment of chronic HBV infection. The results of this retrospective study even with a limited number of patients with the aim of reviewing the real-life data of the patients followed up in our hospital support that TDF is an effective agent in the treatment of chronic HBV infection. However, the results of this study revealed that periodic monitoring of creatinine, GFR and phosphorus levels of patients using TDF is required. In addition, especially in patients at high risk for CKD and hypophosphatemia, shorter periods for follow-up intervals are important for the early detection of possible side effects. Key Words: Chronic Hepatitis B, Tenofovir, Kidney Injury, Creatinine, GFR, Glomerular Filtration Rate, Calcium, Phosphorus