OBJECTIVE: To study the correlations of genetic variants of telbivudine phosphorylase kinases and telbivudine plasma concentration with creatine kinase elevation in chronic hepatitis B patients who received telbivudine.
METHODS: An observational study was performed in China chronic hepatitis B patients receiving telbivudine therapy at 600 mg once daily. Plasma concentration was measured 12 h after taking telbivudine using ultra-performance liquid chromatography-tandem mass spectrometry and SNPs located in RRM2B, TK2, and NME4 was detected by MALDI-TOF mass spectrometry. All statistical analyses were performed with R 4.3.1 and all graphs were drawn by Origin 2023b and P value < 0.05 was considered statistically significant.
RESULTS: A total of 140 patients receiving telbivudine therapy were recruited with a median plasma concentration of 952.49 (781.07-1238.98) ng/mL. The value of plasma concentration was proportional to the grade of creatine kinase elevation and the best telbivudine plasma concentration threshold to discriminate the grade 3/4 CK elevation was 1336.61 ng/mL. Multivariate analysis revealed that plasma concentration and rs3826160 were the independent risk factor of telbivudine-induced creatine kinase elevation. Patients with TC and CC genotype in rs3826160 not only had a higher incidence of creatine kinase elevation but also a higher plasma concentration than TT genotype carriers.
CONCLUSIONS: Chronic hepatitis B patients with TC and CC genotype in rs3826160 have high telbivudine plasma concentration are at risk of elevated creatine kinase.

BACKGROUND: Acute viral myositis (AVM) may be triggered by influenza A/B, enteroviruses and other viruses. Severe complications including rhabdomyolysis regularly lead to acute kidney injury (AKI). The aim of this short report was to discuss management and differential diagnosis of massive creatine kinase (CK) elevation.
UNASSIGNED: Herein, we report on a 19-year-old Austrian male of African descent with a history of respiratory tract infections and whole-body pain. He further developed acute viral myositis and massive CK elevation up to 440,000 IU/L but without any signs of AKI. A literature search relating AVM, management and differential diagnosis of rhabdomyolysis was conducted in PubMed and UptoDate.
RESULTS: A full panel of serological and autoimmune blood work-up including testing for human immunodeficiency virus (HIV), hepatitis, influenza A/B, Epstein-Barr virus (EBV), antinuclear antibodies (ANA) and autoantibodies against various extractable nuclear antigens (ENA) did not reveal evidence for viral originators or autoimmune diseases. This case indicates that in acute viral myositis associated with extreme CK elevation (>400,000 IU/L) AKI might be completely absent. Potential causes for this clinical phenotype, differential diagnosis and management are discussed.

OBJECTIVE: An increasing number of studies are reporting a high frequency of creatine kinase (CK) elevation during telbivudine therapy; however, few reports have focused on the cumulative incidence and risk factors of CK elevation. This study was performed to investigate the cumulative incidence and risk factors of CK elevation in Chinese patients treated with telbivudine.
METHODS: In this observational study, patients with chronic hepatitis B receiving telbivudine therapy between July 2008 and December 2013 were enrolled. The cumulative incidence of CK elevation was analyzed using the Kaplan-Meier method combined with the log rank test. Risk factors were determined using Cox proportional hazards regression models.
RESULTS: A total of 207 eligible patients were analyzed. The cumulative incidence of CK elevation at 12, 24, 36, 48, 60, and 72 months was 51.2 %, 68.9 %, 75.1 %, 78.1 %, 78.1 %, and 78.1 %, respectively. Multivariate analysis revealed that male and lower baseline estimated glomerular filtration rate (eGFR) were significant risk factors for CK elevation.
CONCLUSIONS: The cumulative incidence of CK elevation after long-term telbivudine use is quite high, and gender and baseline eGFR may be useful predictors. However, when combined with regular monitoring of CK levels, especially for patients with lower eGFR, telbivudine is a relatively safe nucleoside analog treatment for chronic hepatitis B.