title: Proximal tubular dysfunction and kidney injury associated with tenofovir in HIV patients: a case series.
abstract: BACKGROUND
  Tenofovir disoproxil fumarate (TDF) may cause acute kidney injury and proximal tubular dysfunction. However, no detailed studies document urinary phosphate wasting as a marker of TDF-induced tubulopathy.
  
  
  METHODS
  Records of HIV-infected patients with presumed TDF toxicity were reviewed. We describe the characteristics and clinical course of 15 patients who had documented elevated (>20%) fractional excretion of phosphate (FEphos).
  
  
  RESULTS
  Patients were predominantly Caucasian and male (73 and 80%, respectively), with a mean age of 56 years (range 38-76). Of the 15 patients, 11 had a estimated glomerular filtration rate (eGFR) of >90 mL/min/1.73(2) at time of TDF initiation. The mean duration of TDF therapy prior to diagnosis of TDF toxicity was 64 months. Mean FEphos was 34% (range 20-62). The mean eGFR at TDF initiation was 104 mL/min/1.73 m(2) [standard deviation (SD) 17.0] with a gradual decline to 69 mL/min/1.73 m(2) (SD 19.0) by the time of TDF discontinuation. Of 10 patients with repeated FEphos after TDF discontinuation, 9 had improvement of their FEphos. Of these individuals, 6 had normalization of their FEphos. Estimated GFR improved in 12 patients after discontinuation of TDF, though importantly, none returned to their baseline eGFR.
  
  
  CONCLUSIONS
  Urinary phosphate wasting is a sensitive marker for TDF-induced proximal tubulopathy and is associated with unrecognized and permanent renal function decline. Tubular dysfunction can develop after years of TDF therapy in those with normal kidney function at the time of drug initiation. This suggests that continuing vigilance be maintained in all those on TDF.
authors.affiliation: Medicine , University of Wisconsin School of Medicine , Madison, WI , USA.
authors.forename: Sana
authors.initials: S
authors.lastname: Waheed
authors.affiliation: Alexandria Faculty of Medicine , Alexandria , Egypt.
authors.forename: Doaa
authors.initials: D
authors.lastname: Attia
authors.affiliation: Medicine , Johns Hopkins School of Medicine , Baltimore, MD , USA.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Estrella
authors.affiliation: CMH Lahore Medical College , Lahore , Pakistan.
authors.forename: Yousuf
authors.initials: Y
authors.lastname: Zafar
authors.affiliation: Medicine , Johns Hopkins School of Medicine , Baltimore, MD , USA.
authors.forename: Mohamed G
authors.initials: MG
authors.lastname: Atta
authors.affiliation: Medicine , Johns Hopkins School of Medicine , Baltimore, MD , USA.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Lucas
authors.affiliation: Medicine , Johns Hopkins School of Medicine , Baltimore, MD , USA.
authors.forename: Derek M
authors.initials: DM
authors.lastname: Fine
keywords: HIV; kidney injury; phosphate wasting; proximal tubular dysfunction; tenofovir