Low-dose adefovir dipivoxil may induce Fanconi syndrome: clinical characteristics and long-term follow-up for Chinese patients.

BACKGROUND: Adefovir dipivoxil (ADV) nephrotoxicity is well known at a dose of 60 mg day(-1) or 120 mg day(-1). However, renal toxicity at a low-dose of 10 mg ADV for HBV-infected patients is not fully described. Our objective was to analyse the clinical features and outcomes of ADV-related Fanconi's syndrome in the Chinese population. METHODS: This was a retrospective study. A total of 35 patients with ADV-related Fanconi's syndrome were studied. Clinical manifestations and biochemical parameters were analysed. 19 patients were from Peking Union Medical College Hospital (PUMCH) included from August 2010 to December 2012. A total of 16 patients were eligible from case reports in the Chinese population retrieved in PUBMED, WANFANG and CNKI database. Bone mineral density and biochemical parameters including serum phosphate, calcium, creatinine, alkaline phosphatase (ALP) were measured before and after ADV cessation and during the follow-up. RESULTS: All recruited patients had hypophosphataemia, increased urinary phosphate excretion and elevated alkaline phosphatase. Serum phosphate levels rapidly increased especially within the 4 weeks after ADV cessation. Serum creatinine remained high or at the upper limit of normal range even after ADV cessation for 1 year. ALP increased in the first three months of ADV cessation and decreased at the 24th week. Bone mineral density was significantly improved after 6 months cessation of ADV. CONCLUSIONS: ADV can be nephrotoxic at prolonged low doses of 10 mg. For those who take ADV long term, regular monitoring of serum phosphate, creatinine levels and urine routine tests are required.

Tenofovir-induced Fanconi syndrome and osteomalacia in two HIV-infected patients: role of intracellular tenofovir diphosphate levels and review of the literature.

We present 2 human immunodeficiency virus-infected patients with tenofovir disoproxil fumarate-induced Fanconi syndrome, leading to osteomalacia. Intracellular tenofovir diphosphate levels were measured in 1 patient and were found to be very high, with plasma tenofovir levels just slightly elevated. Fibroblast growth factor-23, a phosphaturic hormone, was decreased in both patients and is therefore unlikely to have a pathophysiological role in this pathology. The different potential factors contributing to the development of tenofovir-related kidney proximal tubular dysfunction are discussed and the data presented may help to further elucidate its pathogenesis.

Fanconi syndrome in lymphoma patients: report of the first case series.

BACKGROUND: Fanconi syndrome (FS) is a generalized transport defect in the proximal renal tubule leading to renal losses of phosphate, calcium, uric acid, bicarbonates as well as glucose, amino acids and other organic compounds. It is caused by inherited or acquired disorders including low mass or high mass multiple myeloma. OBJECTIVES: To report the first case series of patients with lymphoma and FS. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: Patients with lymphoma and FS were identified in the nephrology department of two teaching hospitals in Paris, France and Ghent, Belgium. FS was defined by the presence of at least three out of the four following criteria: hypophosphataemia, metabolic acidosis, normoglycaemic glucosuria and hypokalaemia. Patients files were reviewed and relevant data were collected. RESULTS: Eight patients with lymphoma and FS were identified. In six patients, the lymphoma was of the acute T cell leukaemia/lymphoma (ATLL) type, related to human T cell lymphotropic virus 1 (HTLV1) infection. In all patients, FS was severe requiring supplementation. A kidney biopsy performed in a patient with post-transplantation primary renal lymphoma disclosed intense proximal tubule infiltration by lymphomatous cells. In one patient with ATLL, FS features regressed following the successful treatment of lymphoma. CONCLUSION: Patients with lymphoma require careful monitoring for features of FS; lymphoma should also be added to the spectrum of disorders associated to FS. Prospective studies are needed to ascertain the implication of HTLV1 in the genesis of FS.

Impact of tenofovir on renal function in HIV-infected, antiretroviral-naive patients.

OBJECTIVE: To better characterize the long-term effects of tenofovir on renal function in a large managed care organization. METHODS: We performed a retrospective cohort analysis in Kaiser Permanente for years 2002 to 2005 comparing renal function among antiretroviral naïve patients initiating a tenofovir-containing regimen (964 patients) or tenofovir-sparing regimens (683 patients). We evaluated glomerular filtration rate (GFR, [Modification of Diet in Renal Disease equation]), serum creatinine, and the development of renal proximal tubular dysfunction. We report multivariable hazard ratios (HR, Cox modeling) and linear outcomes (repeated measures) with predictors retained if P < 0.10 (backward selection). Potential predictor variables included in multivariate models were age, sex, Black race, baseline laboratories (including CD4 count), history of diabetes mellitus, hypertension, malignancy, hepatitis, and concurrent medications. RESULTS: Overall, tenofovir-exposed patients had a larger relative decline in GFR through 104 weeks (-7.6 mL/min/1.73 m(2) relative to tenofovir-sparing, P < 0.001); the degree of the difference varied by baseline GFR, with the greatest effect seen in those patients with GFR greater than 80 mL/min/1.73 m(2). Tenofovir-exposed patients had greater development of proximal tubular dysfunction over time (at 52 wk: HR(adjusted) = 1.95 [P = 0.01] and at 104 wk: HR(adjusted) = 5.23 [P = 0.0004]) and had greater risk of medication discontinuation (HR(adjusted) = 1.21, P = 0.02), especially as renal function worsened. Viral control and CD4 count changes were similar between the two groups. CONCLUSIONS: Tenofovir is associated with greater effect on decline in renal function and a higher risk of proximal tubular dysfunction in antiretroviral naïve patients initiating antiretroviral therapy.

Low bone mineral density, renal dysfunction, and fracture risk in HIV infection: a cross-sectional study.

BACKGROUND: Reduced bone mineral density (BMD) is common in adults infected with human immunodeficiency virus (HIV). The role of proximal renal tubular dysfunction (PRTD) and alterations in bone metabolism in HIV-related low BMD are incompletely understood. METHODS: We quantified BMD (dual-energy x-ray absorptiometry), blood and urinary markers of bone metabolism and renal function, and risk factors for low BMD (hip or spine T score, -1 or less) in an ambulatory care setting. We determined factors associated with low BMD and calculated 10-year fracture risks using the World Health Organization FRAX equation. RESULTS: We studied 153 adults (98% men; median age, 48 years; median body mass index, 24.5; 67 [44%] were receiving tenofovir, 81 [53%] were receiving a boosted protease inhibitor [PI]). Sixty-five participants (42%) had low BMD, and 11 (7%) had PRTD. PI therapy was associated with low BMD in multivariable analysis (odds ratio, 2.69; 95% confidence interval, 1.09-6.63). Tenofovir use was associated with increased osteoblast and osteoclast activity (P< or = .002). The mean estimated 10-year risks were 1.2% for hip fracture and 5.4% for any major osteoporotic fracture. CONCLUSIONS: In this mostly male population, low BMD was significantly associated with PI therapy. Tenofovir recipients showed evidence of increased bone turnover. Measurement of BMD and estimation of fracture risk may be warranted in treated HIV-infected adults.

Causes and consequences of hypokalemia in patients on tenofovir disoproxil fumarate.

To determine the spectrum of clinical manifestations of hypokalemia associated with tenofovir, we reviewed all reports of grades 3/4 hypokalemia received by Gilead Sciences Department of Safety and Public Health. Of 32 cases identified in 2001-2006, 23 were attributed to proximal renal tubular dysfunction, and medically significant conditions attributable to hypokalemia occurred in four, which all improved with medical management. In none of the six fatal cases did hypokalemia appear to contribute to death.

Fanconi's syndrome in HIV+ adults: report of three cases and literature review.

UNLABELLED: We diagnosed Fanconi's syndrome (phosphate depletion and dysfunction of the renal tubules) in three HIV(+) patients. This was temporally related to their HIV treatment. Physicians caring for patients with HIV should recognize the association of this rare syndrome with antiretroviral medications and monitor their patients carefully. INTRODUCTION: Fanconi's syndrome is caused by increased excretion of phosphate, glucose, amino acids, and other intermediary metabolites, and can result in osteomalacia. MATERIALS AND METHODS: We diagnosed this syndrome in three HIV(+) patients. RESULTS: The first was a 43-year-old woman referred for multiple painful stress fractures. She demonstrated hypophosphatemia, metabolic acidosis, phosphaturia, glucosuria, and generalized aminoaciduria. These abnormalities resolved with oral phosphate replacement and discontinuation of the antiretroviral medication tenofovir. The second patient was a 39-year-old man with hypophosphatemia and bone pain. His symptoms improved with discontinuation of adefovir and supplementation of phosphate, potassium, and calcitriol. The third patient was a 48-year-old man who presented with symptomatic tetany caused by hypocalcemia (total serum calcium of 6.5 mg/dl [8.5-10.5 mg/dl]). Nine months before presentation, he had been treated with cidofovir for retinitis caused by cytomegalovirus. With calcium, phosphate, potassium, and calcitriol therapy, his laboratory abnormalities improved substantially, although he continues to require daily electrolyte replacement. CONCLUSIONS: Each patient demonstrated generalized renal tubular dysfunction temporally related to treatment with antiretroviral drugs. The mechanism responsible for these abnormalities is not known; however, physicians caring for patients with HIV disease should recognize the association of Fanconi's syndrome with antiretroviral medications and monitor susceptible patients to prevent potential skeletal and neuromuscular complications.