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Incompatible living donor kidney transplant recipients (ILDKTr) have pre-existing donor-specific antibody (DSA) that, despite desensitization, may persist or reappear with resulting consequences, including delayed graft function (DGF) and acute rejection (AR). To quantify the risk of DGF and AR in ILDKT and downstream effects, we compared 1406 ILDKTr to 17 542 compatible LDKT recipients (CLDKTr) using a 25-center cohort with novel SRTR linkage. We characterized DSA strength as positive Luminex, negative flow crossmatch (PLNF); positive flow, negative cytotoxic crossmatch (PFNC); or positive cytotoxic crossmatch (PCC). DGF occurred in 3.1% of CLDKT, 3.5% of PLNF, 5.7% of PFNC, and 7.6% of PCC recipients, which translated to higher DGF for PCC recipients (aOR = 1.03 1.682.72 ). However, the impact of DGF on mortality and DCGF risk was no higher for ILDKT than CLDKT (p interaction > .1). AR developed in 8.4% of CLDKT, 18.2% of PLNF, 21.3% of PFNC, and 21.7% of PCC recipients, which translated to higher AR (aOR PLNF = 1.45 2.093.02 ; PFNC = 1.67 2.403.46 ; PCC = 1.48 2.243.37 ). Although the impact of AR on mortality was no higher for ILDKT than CLDKT (p interaction = .1), its impact on DCGF risk was less consequential for ILDKT (aHR = 1.34 1.621.95 ) than CLDKT (aHR = 1.96 2.292.67 ) (p interaction = .004). Providers should consider these risks during preoperative counseling, and strategies to mitigate them should be considered.

Among patients with short bowel syndrome who commonly have kidney disease, kidney transplantation remains challenging. We describe the clinicopathologic course of a 59-year old man with short bowel syndrome secondary to Crohn’s disease who underwent a deceased donor kidney transplant that was complicated by recurrent acute kidney allograft injury due to volume depletion from diarrhea, ultimately requiring the placement of permanent intravenous access for daily volume expansion at home resulting in the recovery of allograft function. Teduglutide treatment at 1.8 years post-transplant led to a dramatic decrease in diarrhea. A literature review of similar cases yielded 18 patients who underwent 19 kidney transplants. Despite high rates of complications, at the time of last follow-up (median 2.1 years [0.04-7]), 94% of the patients were still alive and 89% had functioning allografts, with a median eGFR of 37.5 [14-122] ml/min/1.73m2. In conclusion, despite high rates of complications, kidney transplantation in patients with short bowel syndrome is associated with acceptable short- and midterm outcomes. Further, we report for the first time the effects of the glucagon-like peptide-2 analogue teduglutide for short bowel syndrome in a kidney transplant recipient.

BACKGROUND Desensitization protocols for HLA-incompatible living donor kidney transplantation (ILDKT) vary across centers. The impact of these, as well as other practice variations, on ILDKT outcomes remains unknown. METHODS We sought to quantify center-level variation in mortality and graft loss following ILDKT using a 25-center cohort of 1358 ILDKT recipients with linkage to Scientific Registry of Transplant Recipients for accurate outcome ascertainment. We used multilevel Cox regression with shared frailty to determine the variation in post-ILDKT outcomes attributable to between-center differences and to identify any center-level characteristics associated with improved post-ILDKT outcomes. RESULTS After adjusting for patient-level characteristics, only 6 centers (24%) had lower mortality and 1 (4%) had higher mortality than average. Similarly, only 5 centers (20%) had higher graft loss and 2 had lower graft loss than average. Only 4.7% of the differences in mortality (P < 0.01) and 4.4% of the differences in graft loss (P < 0.01) were attributable to between-center variation. These translated to a median hazard ratio of 1.36 for mortality and 1.34 of graft loss for similar candidates at different centers. Post-ILDKT outcomes were not associated with the following center-level characteristics: ILDKT volume and transplanting a higher proportion of highly sensitized, prior transplant, preemptive, or minority candidates. CONCLUSIONS Unlike most aspects of transplantation in which center-level variation and volume impact outcomes, we did not find substantial evidence for this in ILDKT. Our findings support the continued practice of ILDKT across these diverse centers.

At Massachusetts General Hospital, we pioneered simultaneous hematopoietic cell (HCT)/kidney transplantation from HLA-identical related donors for the treatment of hematological malignancies with end-stage renal failure. We have now extended this to HLA-haploidentical donors in a pilot trial. Six recipients, 5 of whom were conditioned with fludarabine, cyclophosphamide, and total-body irradiation, underwent combined HCT/kidney transplantation from haploidentical donors; graft-versus-host disease (GVHD) prophylaxis included post-HCT cyclophosphamide, tacrolimus, and mycophenolate mofetil. One patient died as a result of complications of fludarabine neurological toxicity. No neurological toxicity was observed in subsequent patients who received lower fludarabine doses and more intense postfludarabine dialysis. There were no cases of grade 2 to 4 acute GVHD and 1 case of moderate chronic GVHD by 12 months. One patient experienced relapse of multiple myeloma at 30 months after HCT and died 4 years posttransplantation. Overall, 4 of 6 patients remain alive, without disease relapse and with long-term renal rejection–free survival. This trial was registered at www.clinicaltrials.gov as #NCT01758042.

Kidney transplant is a life-changing procedure, and transplant nephrologists, as part of a larger transplant team, play an important role in the field by managing the complex medical needs of transplant patients. The subspecialty of transplant nephrology, however, faces structural challenges related to its workforce, reporting structures, compensation, research and innovation, and health care information technology. The position of transplant nephrology at the academic and operational intersection of medicine and surgery may limit its access to critical resources, hinder academic promotion, and contribute to physician burnout. The authors provide an overview of the subspecialty transplant nephrology and propose solutions. Collaborative efforts that fortify the subspecialty of transplant nephrology will ultimately improve the lives of patients suffering from kidney disease.

BackgroundRenal transplantation is the optimal treatment for selected patients with end-stage renal disease (ESRD). However, the survival benefit of renal transplantation among patients with ESRD attributed to granulomatosis with polyangiitis (GPA) is unknown.MethodsWe identified patients from the United States Renal Data System with ESRD due to GPA (ESRD-GPA) between 1995 and 2014. We restricted our analysis to waitlisted subjects to evaluate the impact of transplantation on mortality. We followed patients until death or the end of follow-up. We compared the relative risk (RR) of all-cause and cause-specific mortality in patients who received a transplant versus non-transplanted patients using a pooled logistic regression model with transplantation as a time-varying exposure.ResultsDuring the study period, 1525 patients were waitlisted and 946 received a renal transplant. Receiving a renal transplant was associated with a 70% reduction in the risk of all-cause mortality in multivariable-adjusted analyses (RR=0.30, 95% CI 0.25 to 0.37), largely attributed to a 90% reduction in the risk of death due to cardiovascular disease (CVD) (RR=0.10, 95% 0.06–0.16).DiscussionRenal transplantation is associated with a significant decrease in all-cause mortality among patients with ESRD attributed to GPA, largely due to a decrease in the risk of death to CVD. Prompt referral for transplantation is critical to optimise outcomes for this patient population.

Primary mitochondrial diseases (MD) are complex, heterogeneous inherited diseases caused by mutations in either the mitochondrial or nuclear DNA. Glomerular diseases in MD have been reported with tRNA mutation m.3243A>G causing a syndrome of mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS). We describe here a case of focal segmental glomerulosclerosis (FSGS) associated with a new tRNA mutation site. A 34-year-old man with a history of living related kidney transplantation, diabetes, hearing loss, and developmental delay presented to the outpatient clinic with complaints of new behavioral difficulties, worsening symptoms, and brain involvement on imaging. Physical examination was remarkable for difficulty hearing, a pattern of dysarthric speech, and cerebellar gait. Laboratory investigations including lactate levels were unremarkable. Based on this set of clinical circumstances, concern for an underlying genetic abnormality was raised. Multiple metabolic tests were unremarkable. Whole exome sequencing revealed a mitochondrial MT-TW tRNA change at position m.5538G>A. Genotype-phenotype correlations are consistent with this tRNA mutation as a cause of his symptoms. To the best of our knowledge, this is the first case describing FSGS-associated MD caused by an m.5538 G>A mutation. Consideration of an underlying MD should be made in patients presenting with deafness, neurologic changes, diabetes, and renal failure.

Background Voriconazole is frequently used to treat fungal infections in solid organ transplant patients. Recently, there have been reports suggesting that prolonged voriconazole therapy may lead to periostitis. Aim Here we present two cases of voriconazole-induced periostitis in solid organ transplant patients. Case Presentation Voriconazole was given to two transplant patients-one with a liver transplant and the second with a heart transplant, to treat their fungal infections. Both developed voriconazole-induced toxicity. While undergoing voriconazole therapy, they had incapacitating bone pain. The liver transplant patient had to be taken off voriconazole, and the heart transplant patient succumbed to non-voriconazole related causes. Conclusions Voriconazole therapy in two solid organ transplant patients resulted in periostitis. We provide potential etiologies underlying voriconazole-induced periostitis, including fluoride toxicity, abnormalities in the pulmonary vascular bed leading to the production of downstream inflammatory mediators, and abnormal pharmacokinetics of hepatic drug metabolism. In addition to monitoring blood voriconazole trough levels, we suggest careful assessment for musculoskeletal pain in patients undergoing voriconazole treatment for two months or more, particularly if their daily dosages of voriconazole exceed 500 mg per day. Appropriate workup should include measurement of alkaline phosphatase, voriconazole trough and fluoride levels as well as a bone scan. Overall, early recognition of voriconazole-induced musculoskeletal toxicity is important for better morbidity outcomes.

Kidney transplantation has achieved remarkable success over the last century, both technically and scientifically. Sophisticated immunosuppression protocols are now available for the vast majority of patients, rendering hyperacute rejection nearly obsolete, with remarkable improvements in rates of early T-cell-mediated rejection as well. Antimicrobial prophylaxis has advanced dramatically. The economic advantages of kidney transplantation over dialysis are more evident than ever, with transplantation costs falling and dialysis costs continuing to increase. However, long-term graft survival remains suboptimal, due largely to inadequate control of the antibody response. Infection and cancer also remain as depressing clinical endpoints for some kidney recipients, and unacceptable rates of death-with-a-functioning-graft persist. Preemptive transplantation has not been adequately utilized, and limited organ availability continues to preclude many potential recipients from receiving transplants. Programs to create immunologic tolerance remain exciting, though currently limited to a few specialized centers. For these reasons, while many of the original promises of kidney transplantation have been met, significant promises in kidney transplantation remain unfulfilled and great needs remain for a future generation to address.

Background and objectives BK virus reactivation in kidney transplant recipients can lead to progressive allograft injury. Reduction of immunosuppression remains the cornerstone of treatment for active BK infection. Fluoroquinolone antibiotics are known to have in vitro antiviral properties, but the evidence for their use in patients with BK viremia is inconclusive. The objective of the study was to determine the efficacy of levofloxacin in the treatment of BK viremia. Design, setting, participants, & measurements Enrollment in this prospective, multicenter, double-blinded, placebo-controlled trial occurred from July 2009 to March 2012. Thirty-nine kidney transplant recipients with BK viremia were randomly assigned to receive levofloxacin, 500 mg daily, or placebo for 30 days. Immunosuppression in all patients was adjusted on the basis of standard clinical practices at each institution. Plasma BK viral load and serum creatinine were measured monthly for 3 months and at 6 months. Results At the 3-month follow-up, the percentage reductions in BK viral load were 70.3% and 69.1% in the levofloxacin group and the placebo group, respectively ( P =0.93). The percentage reductions in BK viral load were also equivalent at 1 month (58% versus and 67.1%; P= 0.47) and 6 months (82.1% versus 90.5%; P =0.38). Linear regression analysis of serum creatinine versus time showed no difference in allograft function between the two study groups during the follow-up period. Conclusions A 30-day course of levofloxacin does not significantly improve BK viral load reduction or allograft function when used in addition to overall reduction of immunosuppression.

Kidney injury is a common complication of multiple myeloma and other plasma cell dyscrasias, and it is associated with increased mortality. Multiple pathogenic mechanisms can contribute to kidney injury in the patient with myeloma, some of which are the result of nephrotoxic monoclonal Ig and some of which are independent of paraprotein deposition. The pathogenic mechanisms that underlie paraprotein-related kidney disease are increasingly well understood. A novel assay allowing the quantification of free light chains in the serum has aided the diagnosis of new onset disease and allowed for the earlier detection of relapse. Novel myeloma agents have shown considerable promise in reversing renal failure in some patients and improving outcomes. Stem cell transplantation remains a mainstay of management for younger patients with myeloma who are suitable candidates for intensive therapy, whereas the role of new drugs, plasma exchange, and kidney transplantation continues to evolve.

The prevalence of Hepatitis C Virus (HCV) infection is significantly higher in patients with end-stage renal disease compared to the general population and poses important clinical challenges in patients who undergo kidney transplantation. Historically, interferon-based treatment options have been limited by low rates of efficacy and significant side effects, including risk of precipitating rejection. Limited data exist on the use of all-oral, interferon-free direct-acting antiviral (DAA) therapies in kidney transplant recipients. In this study, we performed a retrospective chart review with prospective clinical follow-up of post-kidney transplant patients treated with DAA therapies at three major hospitals in Boston, MA. A total of 24 kidney recipients with HCV infection received all-oral DAA therapy post-transplant. Patients were predominantly male (79%) with a median age of 60 years (range 34-70 years), median creatinine of 1.2 mg/dL (0.66-1.76), and 42% had advanced fibrosis or cirrhosis. The majority had HCV genotype 1a infection (58%). All patients received full-dose sofosbuvir; it was paired with simeprevir (9 patients without and 3 patients with ribavirin), ledipasvir (7 patients without and 1 patient with ribavirin) or ribavirin alone (4 patients). The overall sustained virologic response (SVR12) was 91% (21 out of 23 patients). One patient achieved SVR4 but demised prior to SVR12 check point due to treatment unrelated cause. Two treatment failures were successfully retreated with alternative DAA regimens and achieved SVR. Both initials failures occurred in patients with advanced fibrosis or cirrhosis, with genotype 1a infection, and prior HCV treatment failure. Adverse events were reported in 11 patients (46%) and were managed clinically without discontinuation of therapy. Calcineurin inhibitor trough levels did not significantly change during therapy. In this multi-center series of patients, all-oral DAA therapy appears to be safe and effective in post-kidney transplant patients with chronic HCV infection.

Importance Solid-organ transplant recipients (OTRs) are at an increased risk for skin cancer. Prior studies have demonstrated a reduced incidence of skin cancer in renal OTRs treated with sirolimus. However, little information exists on the use of sirolimus for the prevention of skin cancer in nonrenal OTRs or those already diagnosed as having a posttransplant cancer. Objective To compare subsequent skin cancer formation in a mixed-organ cohort of OTRs who were or were not treated with sirolimus after developing a posttransplant index cancer of any type. Design, Setting, and Participants A 9-year retrospective cohort study at 2 academic tertiary care centers. Electronic medical records were reviewed for OTRs diagnosed as having a posttransplant cancer of any type to determine the type of organ transplanted, pretransplant and posttransplant cancer, and immunosuppressive medications. Patients underwent transplant from January 1, 2000, to December 31, 2008. Data were collected from July 30, 2011, to December 31, 2012, when follow-up was completed, and analyzed from April 28, 2013, to October 4, 2014. Main Outcomes and Measures Factors associated with subsequent skin cancer development were evaluated via multivariate Cox regression analysis. Results Of 329 OTRs with an index posttransplant cancer (100 women and 229 men; mean [SD] age, 56 [19] years), 177 (53.8%) underwent renal transplant; 58 (17.6%), heart transplant; 54 (16.4%), lung transplant; 34 (10.3%), liver transplant; and 6 (1.8%), mixed-organ transplant. Ninety-seven OTRs (29.5%) underwent conversion to sirolimus therapy after diagnosis. One hundred thirty OTRs (39.5%) developed second posttransplant cancers, of which 115 cases (88.5%) were skin cancers. An 11.6% reduction in skin cancer risk was observed in the sirolimus-treated vs non–sirolimus-treated groups overall (26 of 97 [26.8%] vs 89 of 232 [38.4%]; P = .045) and among nonrenal OTRs only (8 of 34 [23.5%] vs 44 of 112 [39.3%], respectively), although the latter difference was not significant ( P = .09). Independent predictors of skin cancer formation after the index posttransplant cancer were history of pretransplant skin cancer (subhazard ratio, 2.1; 95% CI, 1.2-3.7), skin cancer as the index posttransplant cancer (subhazard ratio, 5.5; 95% CI, 2.5-6.4), and sirolimus treatment (subhazard ratio, 0.6; 95% CI, 0.4-0.9). These same risk factors were associated with skin cancer formation when the analysis was limited to nonrenal OTRs. No difference was found in allograft rejection or death between sirolimus-treated and non–sirolimus-treated groups. Conclusions and Relevance In this mixed-organ cohort of OTRs, patients taking sirolimus after developing posttransplant cancer had a lower risk of developing subsequent skin cancer, with no increased risk for overall mortality. Thus, conversion to sirolimus therapy may be considered in OTRs who develop cancer if the risk for skin cancer is of concern. Larger studies are needed to quantify sirolimus-associated risk reduction for other cancer types.

Summary Background and objectives The principle defect in dense deposit disease and C3 glomerulonephritis is hyperactivity of the alternative complement pathway. Eculizumab, a monoclonal antibody that binds to C5 to prevent formation of the membrane attack complex, may prove beneficial. Design, setting, participants, & measurements In this open-label, proof of concept efficacy and safety study, six subjects with dense deposit disease or C3 glomerulonephritis were treated with eculizumab every other week for 1 year. All had proteinuria >1 g/d and/or AKI at enrollment. Subjects underwent biopsy before enrollment and repeat biopsy at the 1-year mark. Results The subjects included three patients with dense deposit disease (including one patient with recurrent dense deposit disease in allograft) and three patients with C3 glomerulonephritis (including two patients with recurrent C3 glomerulonephritis in allograft). Genetic and complement function testing revealed a mutation in CFH and MCP in one subject each, C3 nephritic factor in three subjects, and elevated levels of serum membrane attack complex in three subjects. After 12 months, two subjects showed significantly reduced serum creatinine, one subject achieved marked reduction in proteinuria, and one subject had stable laboratory parameters but histopathologic improvements. Elevated serum membrane attack complex levels normalized on therapy and paralleled improvements in creatinine and proteinuria. Conclusions Clinical and histopathologic data suggest a response to eculizumab in some but not all subjects with dense deposit disease and C3 glomerulonephritis. Elevation of serum membrane attack complex before treatment may predict response. Additional research is needed to define the subgroup of dense deposit disease/C3 glomerulonephritis patients in whom eculizumab therapy can be considered.

Hydroxocobalamin is a recently approved antidote for the treatment of cyanide poisoning. The case presented involves a young patient administered empiric hydroxocobalamin due to suspected cyanide overdose. Due to the development of acute kidney injury and severe metabolic derangement, emergent hemodialysis was initiated. Unfortunately, hemodialysis was confounded by a recurrent “blood leak” alarm. This unforeseen effect was secondary to interference from hydroxocobalamin. Hydroxocobalamin causes orange/red discoloration of bodily fluids and permeates the dialysate. This leads to defraction of light in the effluent path of the blood leak detector from discolored dialysate, which can result in activation of the blood leak alarm and an inability to continue hemodialysis treatment. This case highlights several new and emerging critical concerns with this medication, including the potential consequence of delayed initiation of emergent renal replacement therapy with empiric administration, the need for increased awareness among clinicians of various disciplines, and the need for multidisciplinary communication.

Patients with significant medical comorbidities such as chronic kidney disease (CKD) traditionally have been excluded from hematopoietic stem cell transplantation (HSCT) because of unacceptably high transplant-related morbidity and mortality, an exclusion that can have enormous consequences for patients with CKD from myeloma in particular. Much of the excess HSCT-related morbidity among CKD patients relates to the toxic effects of conditioning regimens, which have a narrow therapeutic index even in patients with normal renal function. Common posttransplant complications are more challenging to prevent and manage in patients with CKD. In selected centers, autologous HSCT is performed with some frequency in patients with advanced CKD and even dialysis-dependent end-stage renal disease (ESRD), with acceptable outcomes, but cure from malignancy rarely is obtained. Allogeneic transplants using reduced-intensity conditioning regimens are being used with increasing frequency in patients with CKD, for both nonmalignant and malignant conditions, relying in the latter case on a graft-versus-malignancy effect to eliminate residual malignancy. In patients with ESRD from myeloma who have suitable donors, simultaneous allogeneic HSCT and kidney transplantation from a human leukocyte antigen-identical sibling provides the opportunity to treat both the malignant condition and the ESRD, avoiding the risks of posttransplant care in a dialysis-dependent patient and freeing the patient of the subsequent burdens of both ongoing dialysis and immunosuppression.

Aim Beginning on March 25, 2015, our institution’s kidney transplant program has implemented a “readiness” protocol, whereby patients are listed after limited workup and comprehensive testing is deferred until the anticipated time to transplantation is approximately 6–12 months. Prior to implementation of this protocol, our histocompatibility laboratory would receive monthly sera for anti-HLA antibody screening immediately upon listing. However, as part of the readiness strategy, the lab now requests monthly samples only when a candidate is predicted to have 6–12 months of waitlist time remaining. The monthly samples are stored and screened in the lab per protocol (every 3 months for most patients). All candidates are also screened once prior to listing and again immediately after listing. Methods Data from our laboratory database and UNOS were analyzed to determine the number of samples received from waitlisted kidney transplant candidates and the number tested in the three-year period before and after implementation of the readiness protocol. Results Our kidney transplant waitlist has grown from 379 candidates on 7/1/2012 to 948 as of 4/5/2018. Despite this rapid growth, the number of samples received from kidney transplant candidates has decreased from 9171 during the three-year period prior to the implementation of readiness (∼3057/year) to 7924 during the subsequent three-year period (∼2641/year). Based on a sample submission rate of ∼7 samples/patient/year, an estimated 4961 samples per year would have been received without the readiness protocol, with an estimated 6669 samples expected for 2018. From 3/25/12–3/24/15, 4730 antibody screening tests on kidney waitlist candidates were performed by Luminex (∼1577 tests/year), compared to a slight increase to 5082 from 3/25/15–3/24/18 (∼1694 tests/year), despite a 2.5-fold increase in patients on the waitlist from 2012–2018. Conclusions Implementation of the readiness protocol has streamlined the pre-transplant testing process and reduced both the number of samples received and the number tested. This has allowed us to manage a greatly increased waitlist with the same level of resources and has resulted in reduced cost per patient.

“In the long run,” the economist John Maynard Keynes wryly observed in his 1923 A Tract on Monetary Reform, “we are all dead.” Given the logistic barriers to performing long-term studies of immunosuppression in kidney-transplant recipients, as well as the associated expense, many transplant professionals are similarly pessimistic about how to determine adequate long-term regimens in the current era, in which short-term results are excellent but late transplant loss remains a vexing problem. More than 14,000 of the 101,000 patients listed for kidney transplantation are awaiting repeat transplantation.1 Mechanisms of late transplant loss remain under investigation; toxic effects of . . .

Plasma cell dyscrasias are frequently encountered malignancies often associated with kidney disease through the production of monoclonal immunoglobulin (Ig). Paraproteins can cause a remarkably diverse set of pathologic patterns in the kidney and recent progress has been made in explaining the molecular mechanisms of paraprotein-mediated kidney injury. Other recent advances in the field include the introduction of an assay for free light chains and the use of novel antiplasma cell agents that can reverse renal failure in some cases. The role of stem cell transplantation, plasma exchange, and kidney transplantation in the management of patients with paraprotein-related kidney disease continues to evolve.

Plasma cell dyscrasias are frequently encountered malignancies which are often associated with kidney disease through the production of monoclonal immunoglobulin (Ig). Recent advances in the field include the availability of an assay for free light chains, the introduction of new agents which more effectively target malignant plasma cells, and refinements in the application of stem-cell transplantation. Well-selected patients with plasma cell dyscrasias whose monoclonal Ig is well controlled may be candidates for kidney transplantation. Kidney transplant patients with allograft dysfunction from recurrent or de novo monoclonal Ig deposition can be successfully identified and treated with these new approaches.

Colorectal cancer can be prevented by the removal of adenomatous polyps during screening colonoscopy, but adequate bowel preparation is required. Oral sodium phosphate (OSP), an effective bowel purgative, is available over the counter and requires a substantially lower volume than polyethylene glycol-based preparative agents. Accumulating reports implicate OSP in electrolyte disturbances as well as acute kidney injury (AKI) in a syndrome termed phosphate nephropathy (a form of nephrocalcinosis). Despite published case reports and case series, the actual incidence, risk factors, and natural history of phosphate nephropathy remain largely undefined. Several recent observational studies have provided new information on these important issues while supporting a link between OSP and acute phosphate nephropathy as well as the development of chronic kidney disease in elderly patients, many of whom had a normal serum creatinine at the time of OSP ingestion. This review summarizes current knowledge about the renal complications of OSP, risk factors for its development, and the pathophysiology of acute and chronic kidney damage in nephrocalcinosis.