Adefovir nephrotoxicity in a renal allograft recipient

Fanconi syndrome induced by the long-term use of tenofovir disoproxil fumarate: a case report and literature review

We present the case of a woman of 50 years of age who experienced widespread bone pain along with digestive symptoms, including nausea and vomiting. She had been prescribed tenofovir disoproxil fumarate (TDF) tablets for the treatment of hepatitis B. Laboratory testing revealed low circulating phosphorus and potassium concentrations and acidosis. A whole-body bone scan revealed abnormal bone metabolism. Rheumatologic and urologic conditions were ruled out, and therefore TDF-induced Fanconi syndrome (FS) and related bone pain was diagnosed. After the TDF was discontinued, the patient's symptoms and laboratory indices significantly improved. In this manuscript, we highlight the clinical manifestations of and laboratory test results associated with FS and summarize the cases of TDF-induced FS reported on PubMed between 2013 and 2022 to improve understanding of FS.

A Systematic Review of Clinical Characteristics and Histologic Descriptions of Acute Tubular Injury

INTRODUCTION

The term "acute tubular injury" (ATI) represents histopathologic renal tubular injury and often manifests clinically as acute kidney injury (AKI). Studies systematically summarizing the clinical presentation and histological changes in human ATI are limited.

METHODS

We used a comprehensive search strategy to search human studies of ATI from 1936 to July 2019. We extracted study characteristics, clinical characteristics, and histologic descriptions of ATI by bright field, immunofluorescence, electron microscopy, and immunohistochemistry. We compared ATI histology as a function of tissue procurement type, timing, and etiologies.

RESULTS

We included 292 studies comprising a total of 1987 patients. The majority of studies (222 of 292, 76%) were single-center case reports. The mean age of included patients was 47 years. In native kidney biopsy cases, baseline, peak, and latest creatinine were 1.3 mg/dl, 7.19 mg/dl, and 1.85 mg/dl respectively, and biopsy was performed mostly after peak creatinine (86.7%, 391 of 451). We identified 16 histologic descriptions of tubular injury, including tubular cell sloughing (115 of 292, 39.4%), tubular epithelial flattening/simplification (110 of 292, 37.7%), tubular dilatation (109 of 292, 37.3%), and tubular cell necrosis (93 of 292, 31.8%). There was no difference in tubular injury histology among different tissue procurement types (native kidney biopsy, transplant kidney biopsy, and autopsy), among different etiologies, or between different tissue procurement timing (before or after creatinine peaks in native kidneys). Electron microscopy and immunohistochemistry were used in a minority of studies.

CONCLUSION

ATI manifests with diverse histologic changes. Efforts to establish protocols to harmonize biopsy practices, to handle kidney biopsy for tissue interrogation, and to report results across clinical practice are needed to improve our understanding of this complex disease.

Long-term adefovir therapy may induce Fanconi syndrome: A report of four cases

Fanconi syndrome is a rare disease characterized by dysfunction of the proximal renal tubules as a result of various pathogenic events. Drug-induced Fanconi syndrome may be neglected or misdiagnosed, which increases the level of suffering. The aim of the present study was to conduct an investigation into the effects of adefovir (ADV)-induced Fanconi syndrome. Four typical cases of Fanconi syndrome caused by long-term ADV therapy (2-9 years) were diagnosed at our hospital. A complete medical and therapy history was collected from all four patients prior to a physical examination. Laboratory and diagnostic examinations were also conducted. Following this, the patients were diagnosed and a treatment regimen was decided upon. Outcomes of the treatment regimen were observed. Common manifestations of all the four patients were: Renal tubular reabsorption dysfunction; imbalanced electrolyte acid-base ratio; elevated cystatin C levels; severe hypophosphatemia and diffused systemic pain; osteoporosis; and difficultly walking. When ADV was replaced with supportive treatment, all the four patients exhibited symptom relief. These findings indicate that long-term ADV therapy may induce Fanconi syndrome. For patients with a history of such therapy, the possibility of Fanconi syndrome should be assessed and monitored closely for indicators, including altered glomerular and renal tubular function. Once diagnosed, the agent should be immediately discontinued and prompt symptomatic treatment should be administered.

Adefovir dipivoxil-induced Fanconi syndrome and its predictive factors: A study of 28 cases

The aim of the present study was to identify monitoring and prevention measures as well as predictive factors for early detection of renal toxicity associated with long-term administration of adefovir dipivoxil in order to avoid progression to Fanconi syndrome. Clinical data of 28 patients with Fanconi syndrome caused by long-term administration of adefovir dipivoxil for the treatment of chronic hepatitis B virus (HBV) infection were collected pre-and post-administration for analysis. Patients presented with fatigue, progressive systemic pain in multiple bones and joints, as well as difficulty in walking and pathological fractures in a number of severe cases. Laboratory examinations revealed hypophosphatemia, elevated serum cystatin C (Cys-C), elevated serum creatinine (SCr), reduced glomerular filtration rate (GFR), positive urinary protein, erythrocytes and glucose, as well as osteoporosis. In consequence, adefovir dipivoxil administration was stopped, and patients received concentrated divitamins, sodium phosphate syrup and calcitriol. Symptoms and abnormalities in laboratory examinations were significantly improved in all patients after 2-6 months. Therefore, serum phosphate, SCr, routine urine parameters, Cys-C and GFR should be monitored regularly in chronic HBV patients treated with adefovir dipivoxil. The following factors were identified as predictive of kidney damage and Fanconi syndrome: Age ≥40 years, living in rural areas, previous renal toxicity, estimated GFR (eGFR) <90 ml/min/1.73 m², hypertension, diabetes, cirrhosis and duration of adefovir dipivoxil treatment exceeding 24 months. The present results indicate that timely termination of adefovir dipivoxil treatment and replacement with other antiviral agents is critical once renal impairment appears, and that it is necessary to change to other antiviral agents and prolong the interval of administration according to the eGFR level.