[A Case of Tenofovir-associated Fanconi Syndrome in Patient with Chronic Hepatitis B]

Safety of current antiviral drugs for chronic hepatitis B

INTRODUCTION

Oral nucleos(t)ide analogues (NUCs) are recommended as first-line therapy for chronic hepatitis B due to higher HBV-DNA suppression rates and safety profile. Long-term treatment with NUCs is often necessary to achieve durable viral suppression.

AREAS COVERED

This review provides an overview of the long-term safety data that have become available since entecavir (ETV) and tenofovir disoproxil fumarate (TDF) were first approved, and recent data on tenofovir alafenamide (TAF) in patients with CHB.

EXPERT OPINION

NUCs generally show remarkable safety in patients taking them for long periods. Nevertheless, renal and bone toxicity may occur in a minority of patients on TDF therapy. These effects have been overcome by the recent release of TAF. Moreover, the currently available data do not allow firm conclusions on superiority of TDF on ETV about HCC risk reduction. Observational studies involving more homogeneous cohorts are therefore needed; furthermore long-term studies assessing impact of TAF on this important topic are warranted.

A novel evidence of serial changes of bone mineral density in chronic hepatitis B patients treated with entecavir

BACKGROUND AND AIMS

Tenofovir disoproxil fumarate (TDF) and Entecavir (ETV) are commonly used for patients with chronic hepatitis B (CHB), and renal or bone toxicity are possible concerns. This study is to evaluate the renal and bone effect of TDF compared with ETV in CHB patients.

METHODS

This is a retrospective study at Kaohsiung Chung-Gung memorial hospital, Taiwan, from June 2013 to December 2018. Patients with CHB were prescribed with TDF or ETV for 3 years or above. Renal function was assessed at 12-week intervals. Dual-energy X-ray absorptiometry scans of the spine and femurs were performed at 48-week intervals. The propensity score analysis was conducted to balance the baseline characteristics of patients in both treatment groups.

RESULTS

A total of 258 patients were included in this study: TDF (n = 135) and ETV (n = 123). The prevalence of osteopenia was much higher in the TDF group at week 48 and week 96. The TDF group showed significant mean percentage decrease from baseline in bone mineral density throughout the treatment course. Logistic regression analysis adjusted for the propensity score demonstrated that the use of TDF was the only predictive factor of significant bone density loss at week 144. The mean percentage decline of estimated glomerular filtration rate was significant in the TDF group at all time points. Renal threshold phosphate concentration was similar among both treatment groups.

CONCLUSIONS

This study suggested CHB patients treated with TDF may experience increased risks of bone loss and renal deficits compared to those treated with ETV.

Pathologic femoral fracture due to tenofovir-induced Fanconi syndrome in patient with chronic hepatitis B: A case report

RATIONALE

We report a case of a hepatitis B virus (HBV)-positive patient with preexisting bone disease who developed tenofovir-induced Fanconi syndrome and subsequently sustained pathologic fracture. To our best knowledge, this is the first report in the English literature about pathologic femoral fracture due to tenofovir-induced Fanconi syndrome in patient with chronic hepatitis B (CHB). The present report describes detailed our experience with the diagnosis of pathologic femoral fracture due to tenofovir-induced Fanconi syndrome and treatment.

PATIENT CONCERNS

A 45-year-old man visited our hospital with pain in the right thigh region and gait disturbance which had started 3 months ago and worsened 1 week before admission. The patient was diagnosed with CHB in 2004. He was on lamivudine medication for 2 years. Medication for the patient was subsequently changed to adefovir in 2009 and tenofovir disoproxil fumarate (TDF) in 2013. He was on TDF since 2013.

DIAGNOSIS

His hip joint magnetic resonance imaging (MRI) revealed hypointensity lesions and cortical bone destruction in fat-saturated MR image at the iliopsoas muscle attachment site of the lesser trochanter of both femur. On blood test showed 25-OH vitamin D level at 6.42 ng/mL (normal range, >20 ng/mL) and U-deoxypyridinoline level at 7.60 nM/mMcr (normal range, 2.30-5.40 nM mMcr). However, osteocalcin and parathyroid hormone levels were within normal range. Based on these findings, the present case was concluded as tenoforvir-induced Fanconi syndrome.

INTERVENTIONS

TDF treatment was discontinued. After cooperation with internal medicine department, in order to prevent further fractures of the right lesser trochanter, internal fixation was performed under spinal anesthesia using compression hip nails (APIS, TDM, Korea).

OUTCOMES

Positive outcome by medication and operation demonstrates that his phosphorus and serum calcium levels were maintained within normal range and pain in the right thigh region was improved from visual analogue pain score (VAS) 7 before surgery to VAS 2 after surgery.

LESSONS

Physicians need to regularly monitor bone metabolism in patients with take in tenofovir for early diagnosis before its progression to pathologic fractures.