Patients with chronic Hepatitis B who are under oral antiviral treatment for at least 6 months at study start will be monitored once yearly for kidney function changes within their routine outpatient visit. Therefore urine samples will be collected and some additional blood test will be done within the routine blood sampling.

This non-interventional, long-term observational cohort study will evaluate demographic, clinical, biochemical and virological parameters of outpatients with chronic Hepatitis B who are under oral antiviral treatment with an approved Nucleos(t)ide for > 6 months at study inclusion.

During their routine outpatient visits annually an assessment of their kidney function especially for a proximal tubular dysfunction will be performed and their comedication will be explored. Patients included in the study are followed up for 5 years.

Inclusion Criteria:

• chronic Hepatitis B Virus infection
• indication for an antiviral treatment due to the recent german Hepatitis B guidelines and oral intake of an approved Nucleos(t)ide for a minimum of 6 months at inclusion
• ALT < 2 x UNL (upper normal limit) at study inclusion
• age 18 - 89 years
• signed informed consent form

Exclusion Criteria:

• coinfection with Hepatitis D Virus (HDV), Hepatitis C Virus (HCV) or Human Immunodeficiency Virus (HIV)
• Comorbidities that will hinder the study performance (e.g. malignancies, relevant psychiatric disorder)
• hepatocellular carcinoma or hepatic metastases
• legally incapacitated patients

Patients with chronic Hepatitis B under oral antiviral treatment with an approved Nucleos(t)ice for a minimal duration of 6 months at study inclusion