Tenofovir-associated renal and bone toxicity

The Mortimer Market Centre, Camden PCT, London, UK.
HIV Medicine (Impact Factor: 3.99). 06/2009; 10(8):482-7. DOI: 10.1111/j.1468-1293.2009.00716.x
Source: PubMed

ABSTRACT The aims of the study were to describe the clinical presentation and renal and bone abnormalities in a case series of HIV-infected patients receiving treatment with tenofovir (TDF), and to recommend appropriate screening for toxicity related to TDF.
Patients were identified from referrals to a specialist HIV renal clinic. Patients were included if treatment with TDF was assessed as the primary cause of the renal function impairment and clinical data were available prior to and following discontinuation of TDF treatment. Data were collected from case note review and clinic databases.
Twenty-two patients (1.6% of all those who received TDF) were identified with TDF-associated renal toxicity. All had normal serum creatinine prior to TDF therapy. All presented with proteinuria. On stopping TDF, renal function improved. Eight patients had confirmed Fanconi syndrome. Twelve patients presented with bone pain and osteomalacia was confirmed on an isotope bone scan in seven of these patients. The findings (in those patients tested) of tubular proteinuria, reduced tubular transport maximum of phosphate (TmP), and glycosuria were all consistent with the proximal tubule being the site of toxicity.
Renal toxicity remains a concern in patients treated with TDF. Clinical presentation may be with renal dysfunction, Fanconi syndrome or osteomalacia. Our investigations suggest proximal tubular toxicity as a common pathogenic mechanism.

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Available from: Devaki R Nair, Jan 04, 2015
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    • "In the TDF treated HIV patients who underwent kidney biopsy, the main abnormality on light microscopy was acute proximal tubule damage, and the presence of intracytoplasmic inclusions. Electron microscopy showed widespread morphologic abnormalities in proximal tubule mitochondria, with marked variations in size and shape , disruption of cristae, mitochondrial swelling, and intra-mitochondrial deposits [7,14]. "
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    ABSTRACT: Nephrotoxicity is a dose limiting side effect of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection. The mechanism of tenofovir nephrotoxicity is not clear. Tenofovir is specifically toxic to the proximal convoluted tubules and proximal tubular mitochondria are the targets of tenofovir cytotoxicity. Damaged mitochondria are major sources of reactive oxygen species and cellular damage is reported to occur after the antioxidants are depleted. The purpose of the study is to investigate the alterations in cellular antioxidant system in tenofovir induced renal damage using a rat model. Chronic tenofovir administration to adult Wistar rats resulted in proximal tubular damage (as evidenced by light microscopy), proximal tubular dysfunction (as shown by Fanconi syndrome and tubular proteinuria), and extensive proximal tubular mitochondrial injury (as revealed by electron microscopy). A 50% increase in protein carbonyl content was observed in the kidneys of TDF treated rats as compared with the control. Reduced glutathione was decreased by 50%. The activity of superoxide dismutase was decreased by 57%, glutathione peroxidase by 45%, and glutathione reductase by 150% as compared with control. Carbonic Anhydrase activity was decreased by 45% in the TDF treated rat kidneys as compared with control. Succinate dehydrogenase activity, an indicator of mitochondrial activity was decreased by 29% in the TDF treated rat kidneys as compared with controls, suggesting mitochondrial dysfunction CONCLUSION: Tenofovir- induced mitochondrial damage and increased oxidative stress in the rat kidneys may be due to depletion of the antioxidant system particularly, the glutathione dependent system and MnSOD.
    Journal of Biomedical Science 08/2013; 20(1):61. DOI:10.1186/1423-0127-20-61 · 2.76 Impact Factor
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    • "The absence of a significant association between raised RBPCR and TFV exposure in general, or TFV/PI exposure more specifically, may relate to the fact that our patients had no evidence of clinical renal tubular toxicity, the size and heterogeneity of the cohort, the assay or the RBPCR cut-off chosen for our analyses, or unmeasured confounding. Of note, the median RBPCR in a previous study of patients with TFV-induced Fanconi syndrome was 5593 μg/mmol (49,515 μg/g) [21], which is approximately 100-fold higher than the upper limit of the reference range of the assay used in our study. As almost all of our patients had RBPCR measurements within (or slightly above) the reference range, RBPCR appears to have good discriminatory value between severe, treatment-limiting renal tubular disease and normal tubular function or mild, asymptomatic renal tubular dysfunction. "
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    ABSTRACT: Chronic kidney disease is common in HIV positive patients and renal tubular dysfunction has been reported in those receiving combination antiretroviral therapy (cART). Tenofovir (TFV) in particular has been linked to severe renal tubular disease as well as proximal tubular dysfunction. Markedly elevated urinary concentrations of retinal-binding protein (RBP) have been reported in patients with severe renal tubular disease, and low-molecular-weight proteins (LMWP) such as RBP may be useful in clinical practice to assess renal tubular function in patients receiving TFV. We analysed 3 LMWP as well as protein and albumin in the urine of a sample of HIV positive patients. In a cross-sectional fashion, total protein, albumin, RBP, cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL) were quantified in random urine samples of 317 HIV positive outpatients and expressed as the ratio-to-creatinine (RBPCR, CCR and NGALCR). Exposure to cART was categorised as none, cART without TFV, and cART containing TFV and a non-nucleoside reverse-transcriptase-inhibitor (TFV/NNRTI) or TFV and a protease-inhibitor (TFV/PI). Proteinuria was present in 10.4 % and microalbuminuria in 16.7 % of patients. Albumin accounted for approximately 10 % of total urinary protein. RBPCR was within the reference range in 95 % of patients while NGALCR was elevated in 67 % of patients. No overall differences in urine protein, albumin, and LMWP levels were observed among patients stratified by cART exposure, although a greater proportion of patients exposed to TFV/PI had RBPCR >38.8 μg/mmol (343 μg/g) (p = 0.003). In multivariate analyses, black ethnicity (OR 0.43, 95 % CI 0.24, 0.77) and eGFR <75 mL/min/1.73 m2 (OR 3.54, 95 % CI 1.61, 7.80) were independently associated with upper quartile (UQ) RBPCR. RBPCR correlated well to CCR (r2 = 0.71), but not to NGALCR, PCR or ACR. In HIV positive patients, proteinuria was predominantly of tubular origin and microalbuminuria was common. RBPCR in patients without overt renal tubular disease was generally within the reference range, including those receiving TFV. RBP therefore appears a promising biomarker for monitoring renal tubular function in patients receiving TFV and for distinguishing patients with normal tubular function or mild tubular dysfunction from those with severe renal tubular disease or Fanconi syndrome.
    BMC Nephrology 08/2012; 13(1):85. DOI:10.1186/1471-2369-13-85 · 1.69 Impact Factor
    • "TDF is generally considered safe; however, renal toxicity has been reported with its use.[5–9] Even though TDF most often has been reported to cause proximal renal tubulopathy, e.g., Fanconi syndrome, other related nephrotoxicities, including diabetes insipidus, calcium and phosphorus dysregulation with bone disease,[10] and reduction in glomerular function have also been reported.[1112] Although the incidence of nephrotoxicity appears to be low (ranging from 0.3 to 2%), many caregivers will see this complication develop due to the agent’s widespread use. "
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    ABSTRACT: Tenofovir (TDF) is preferred nucleoside reverse transcriptase inhibitors (NRTI) for the treatment of human immunodeficiency virus infection because of its potency and safety. Renal toxicity with TDF use is low and comparable with other NRTI in clinical trials, but there are many case studies and small case series of renal dysfunction with TDF. This is an observational longitudinal cohort of patients started on a TDF-based regimen from January 2007 to April 2010. Patients were evaluated at baseline and with every follow-up visit for serum creatinine and calculated creatinine clearance (Cockroft-Gault formula). In addition to this, the patients were also subjected to test for serum potassium, phosphorous and urine examinations as and when indicated. Renal dysfunction was defined as rise in serum creatinine to more than the upper level of normal (>1.2 mg%). Of 1,271 patients started on a TDF-containing antiretroviral treatment (ART) 83 (6.53%) developed renal dysfunction, of which 79 had impaired serum creatinine and five had Fanconi's syndrome. Renal dysfunction was more common with boosted a protease inhibitor (PI) (9.44%)-based regimen as compared to a non- nucleoside reverse transcriptase inhibitors (NNRTI) (5.01%)-based regimen (P = 0.003). The mean decline in creatinine clearance from baseline was 22.27 ml/min. The median time to develop renal dysfunction was 154 (15-935) days. Serum creatinine returned to normal in all the patients after stopping TDF. Five patients presented with features suggestive of Fanconi's syndrome without alteration in serum creatinine. TDF-based treatment is associated with mild but reversible renal dysfunction. Patients receiving PI/r are at a higher risk of renal dysfunction compared to those receiving NNRTI-based ART. Clinicians should be adviced to have intensive renal monitoring, including creatinine clearance, urine examination, K+ and phosphate levels at baseline and during treatment with TDF.
    Indian Journal of Sexually Transmitted Diseases and AIDS 03/2010; 31(1):30-4. DOI:10.4103/0253-7184.68998
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