Plasma Kidney Injury Molecule 1 in CKD: Findings From the Boston Kidney Biopsy Cohort and CRIC Studies.

RATIONALE & OBJECTIVE: Plasma kidney injury molecule 1 (KIM-1) is a sensitive marker of proximal tubule injury, but its association with risks of adverse clinical outcomes across a spectrum of kidney diseases is unknown. STUDY DESIGN: Prospective, observational cohort study. SETTING & PARTICIPANTS: 524 individuals enrolled into the Boston Kidney Biopsy Cohort (BKBC) Study undergoing clinically indicated native kidney biopsy with biopsy specimens adjudicated for semiquantitative scores of histopathology by 2 kidney pathologists and 3,800 individuals with common forms of chronic kidney disease (CKD) enrolled into the Chronic Renal Insufficiency Cohort (CRIC) Study. EXPOSURE: Histopathologic lesions and clinicopathologic diagnosis in cross-sectional analyses, baseline plasma KIM-1 levels in prospective analyses. OUTCOMES: Baseline plasma KIM-1 levels in cross-sectional analyses, kidney failure (defined as initiation of kidney replacement therapy) and death in prospective analyses. ANALYTICAL APPROACH: Multivariable-adjusted linear regression models tested associations of plasma KIM-1 levels with histopathologic lesions and clinicopathologic diagnoses. Cox proportional hazards models tested associations of plasma KIM-1 levels with future kidney failure and death. RESULTS: In the BKBC Study, higher plasma KIM-1 levels were associated with more severe acute tubular injury, tubulointerstitial inflammation, and more severe mesangial expansion after multivariable adjustment. Participants with diabetic nephropathy, glomerulopathies, and tubulointerstitial disease had significantly higher plasma KIM-1 levels after multivariable adjustment. In the BKBC Study, CKD in 124 participants progressed to kidney failure and 85 participants died during a median follow-up time of 5 years. In the CRIC Study, CKD in 1,153 participants progressed to kidney failure and 1,356 participants died during a median follow-up time of 11.5 years. In both cohorts, each doubling of plasma KIM-1 level was associated with an increased risk of kidney failure after multivariable adjustment (hazard ratios of 1.19 [95% CI, 1.03-1.38] and 1.10 [95% CI, 1.06-1.15] for BKBC and CRIC, respectively). There was no statistically significant association of plasma KIM-1 levels with death in either cohort. LIMITATIONS: Generalizability and unmeasured confounding. CONCLUSIONS: Plasma KIM-1 is associated with underlying tubulointerstitial and mesangial lesions and progression to kidney failure in 2 cohort studies of individuals with kidney diseases.

Histopathologic Correlates of Kidney Function: Insights From Nephrectomy Specimens.

RATIONALE & OBJECTIVE: Existing data sets correlating kidney histopathologic findings with kidney function have low proportions of elderly patients (and those with a family history of kidney failure are over-represented), which limits their generalizability. Our objective was to use non-neoplastic tissue from nephrectomy specimens to examine the association between degree of histopathologic changes and estimated glomerular filtration rate (eGFR) and determine whether the association differed by age. STUDY DESIGN: Cross-sectional study. EXPOSURES: Glomerulosclerosis (GS), interstitial fibrosis/tubular atrophy (IFTA), and arterial sclerosis/arteriosclerosis (AS). OUTCOME: eGFR. ANALYTICAL APPROACH: We retrospectively reviewed kidney pathology reports (of non-neoplastic tissue) from 1,347 patients who underwent nephrectomy (1999-2018) for any indication but most commonly due to kidney cancer. We evaluated the association between degree of GS, IFTA, and AS with eGFR at the time of nephrectomy and whether this was modified by age. RESULTS: Among the participants (aged 17-91 years), 42% and 57.8% had>10% GS and IFTA, respectively, and 81.8% had moderate or severe AS. We found that greater degrees of GS, IFTA, and AS were associated with lower eGFR after multivariable adjustment. Although there was a greater prevalence of more severe degrees of GS and IFTA in older individuals, the association between various histopathologic features and eGFR was not modified by age. LIMITATIONS: Retrospective cross-sectional study. CONCLUSIONS: Our study demonstrates differences in the histologic appearance of the kidneys across levels of eGFR. Although the prevalence of advanced changes was higher in the oldest group of patients, a subset had excellent kidney function and limited histologic changes.

Improving hepatitis B vaccination rates for advanced chronic kidney disease patients: a quality improvement initiative.

INTRODUCTION: Chronic kidney disease (CKD) patients are vulnerable to hepatitis B, and immunization prior to end stage kidney disease is recommended to optimize seroconversion. Our institution undertook a process improvement approach to increase hepatitis B vaccination in stage 4 and 5 CKD patients. METHODS: Four strategies were utilized such as: (1) Electronic health record (EHR)-based CKD registry to identify patients, (2) EHR-based physician/nurse reminders, (3) a co-located nurse appointment for vaccine administration, and (4) information sharing and provider awareness effort. The CKD registry was utilized to identify patients with stage 4 or 5 CKD, with at least two clinic visits in the prior 2 years, who had not received the hepatitis B vaccine or did not have serologic evidence of immunity. Target monthly vaccination rate was set at 75%, based on clinic leadership, nephrologist, and nurse consensus. RESULTS: A total of 239 patients were included in the study period, from November 2018 to January 2019 (observation period) and from February 2019 to September 2019 (intervention period). Monthly vaccination rate improved from 48% in November 2018 to the target rate of 75% by the end of the intervention (August and September 2019). There was a statistically significant increase from the rate of vaccination at a unique patient level in the first month of the baseline period, compared to the last month of the intervention period (51 vs. 75% p = 0.03). CONCLUSIONS: Utilizing a nurse-led approach to hepatitis B vaccination, coupled with EHR-based tools, along with continuous monitoring of performance, helped to improve hepatitis B vaccination among CKD stage 4 and 5 patients.

Renal deposits of complement factors as predictors of end-stage renal disease and death in patients with lupus nephritis.

OBJECTIVE: Lupus nephritis (LN) increases the risks of end-stage renal disease (ESRD) and death, but these risks are difficult to estimate. Since complement factors play an essential role in the pathogenesis and are deposited in the kidneys as C1q and C3, we studied whether these deposits predict ESRD and death in patients with LN. METHODS: We collected demographic, clinical and pathological data from 183 adult patients with LN classes II-V diagnosed with a first native kidney biopsy. Pathological data included the localization and intensity of immunofluorescence staining of C1q and C3. We obtained dates of incident ESRD and death from the United States Renal Data System and National Death Index, respectively, and evaluated survival curves and hazard ratios for ESRD and death as a composite outcome and as separate outcomes. RESULTS: The presence and intensity of deposits of C1q and C3 in glomeruli, tubular walls and vascular walls differed between classes and were associated with known unfavourable prognostic factors, such as hypertension, hypoalbuminemia and hypocomplementemia. However, over a median follow-up of 7.5 years, their presence and intensity were associated with neither survival free of ESRD and death nor hazard ratios for ESRD and death. CONCLUSION: Renal deposits of complement factors did not predict ESRD and death in patients with LN.

The association of calcium oxalate deposition in kidney allografts with graft and patient survival.

BACKGROUND: Whether calcium oxalate (CaOx) deposition in kidney allografts following transplantation (Tx) adversely affects patient outcomes is uncertain, as are its associated risk factors. METHODS: We performed a retrospective cohort study of patients who had kidney allograft biopsies performed within 3 months of Tx at Brigham and Women's Hospital and examined the association of CaOx deposition with the composite outcome of death or graft failure within 5 years. RESULTS: Biopsies from 67 of 346 patients (19.4%) had CaOx deposition. In a multivariable logistic regression model, higher serum creatinine [odds ratio (OR) = 1.28 per mg/dL, 95% confidence interval (CI) 1.15-1.43], longer time on dialysis (OR = 1.11 per additional year, 95% CI 1.01-1.23) and diabetes (OR = 2.26, 95% CI 1.09-4.66) were found to be independently associated with CaOx deposition. CaOx deposition was strongly associated with delayed graft function (DGF; OR = 11.31, 95% CI 5.97-21.40), and with increased hazard of the composite outcome after adjusting for black recipient race, donor type, time on dialysis before Tx, diabetes and borderline or acute rejection (hazard ratio 1.90, 95% CI 1.13-3.20). CONCLUSIONS: CaOx deposition is common in allografts with poor function and portends worse outcomes up to 5 years after Tx. The extent to which CaOx deposition may contribute to versus result from DGF, however, cannot be determined based on our retrospective and observational data. Future studies should examine whether reducing plasma and urine oxalate prevents CaOx deposition in the newly transplanted kidney and whether this has an effect on clinical outcomes.

Prolyl-hydroxylase inhibitors for the treatment of anemia in chronic kidney disease.

PURPOSE OF REVIEW: Prolyl-hydroxylase inhibitors are a novel class of orally administered drugs that are under development for the treatment of anemia in patients with chronic kidney disease. This review discusses the biology of these drugs and their target - hypoxia-inducible factor and potential advantages and disadvantages of these therapies. Finally, we will discuss current trials in patients with both chronic kidney disease and end-stage renal disease. RECENT FINDINGS: Recent smaller studies have found that prolyl-hydroxylase are as effective as erythropoietin in treating anemia of chronic kidney disease. We do not yet know if they have the same cardiovascular and cancer-related risk profile and these questions will be answered by large phase III trials that are ongoing. SUMMARY: Although prolyl hydroxylase inhibitors have much potential, questions remain regarding their efficacy and safety. Should these concerns prove to be unfounded, the treatment of anemia in chronic kidney disease will likely be transformed over the next decade.

The Prognostic Value of Histopathologic Lesions in Native Kidney Biopsy Specimens: Results from the Boston Kidney Biopsy Cohort Study.

Background Few studies have evaluated whether histopathologic lesions on kidney biopsy provide prognostic information beyond clinical and laboratory data.Methods We enrolled 676 individuals undergoing native kidney biopsy at three tertiary care hospitals into a prospective, observational cohort study. Biopsy specimens were adjudicated for semiquantitative scores in 13 categories of histopathology by two experienced renal pathologists. Proportional hazards models tested the association between histopathologic lesions and risk of kidney disease progression (≥40% eGFR decline or RRT).Results Mean baseline eGFR was 57.5±36.0 ml/min per 1.73 m2 During follow-up (median, 34.3 months), 199 individuals suffered kidney disease progression. After adjustment for demographics, clinicopathologic diagnosis, and laboratory values, the following lesions (hazard ratio; 95% confidence interval) were independently associated with progression: inflammation in nonfibrosed interstitium (0.52; 0.32 to 0.83), moderate and severe versus minimal interstitial fibrosis/tubular atrophy (2.14; 1.24 to 3.69 and 3.42; 1.99 to 5.87, respectively), moderate and severe versus minimal global glomerulosclerosis (2.17; 1.36 to 3.45 and 3.31; 2.04 to 5.38, respectively), moderate and severe versus minimal arterial sclerosis (1.78; 1.15 to 2.74 and 1.64; 1.04 to 2.60, respectively), and moderate and severe versus minimal arteriolar sclerosis (1.63; 1.08 to 2.46 and 2.33; 1.42 to 3.83, respectively). An 11-point chronicity score derived from semiquantitative assessments of chronic lesions independently associated with higher risk of kidney disease progression (hazard ratio per one-point increase, 1.19; 95% confidence interval, 1.12 to 1.27).Conclusions Across a diverse group of kidney diseases, histopathologic lesions on kidney biopsy provide prognostic information, even after adjustment for proteinuria and eGFR.

NFAT5 and SLC4A10 Loci Associate with Plasma Osmolality.

Disorders of water balance, an excess or deficit of total body water relative to body electrolyte content, are common and ascertained by plasma hypo- or hypernatremia, respectively. We performed a two-stage genome-wide association study meta-analysis on plasma sodium concentration in 45,889 individuals of European descent (stage 1 discovery) and 17,637 additional individuals of European descent (stage 2 replication), and a transethnic meta-analysis of replicated single-nucleotide polymorphisms in 79,506 individuals (63,526 individuals of European descent, 8765 individuals of Asian Indian descent, and 7215 individuals of African descent). In stage 1, we identified eight loci associated with plasma sodium concentration at P<5.0 × 10-6 Of these, rs9980 at NFAT5 replicated in stage 2 meta-analysis (P=3.1 × 10-5), with combined stages 1 and 2 genome-wide significance of P=5.6 × 10-10 Transethnic meta-analysis further supported the association at rs9980 (P=5.9 × 10-12). Additionally, rs16846053 at SLC4A10 showed nominally, but not genome-wide, significant association in combined stages 1 and 2 meta-analysis (P=6.7 × 10-8). NFAT5 encodes a ubiquitously expressed transcription factor that coordinates the intracellular response to hypertonic stress but was not previously implicated in the regulation of systemic water balance. SLC4A10 encodes a sodium bicarbonate transporter with a brain-restricted expression pattern, and variant rs16846053 affects a putative intronic NFAT5 DNA binding motif. The lead variants for NFAT5 and SLC4A10 are cis expression quantitative trait loci in tissues of the central nervous system and relevant to transcriptional regulation. Thus, genetic variation in NFAT5 and SLC4A10 expression and function in the central nervous system may affect the regulation of systemic water balance.

Urinary metabolites along with common and rare genetic variations are associated with incident chronic kidney disease.

We assessed the association between urinary metabolites, genetic variants, and incident chronic kidney disease (CKD) in the Framingham Offspring cohort. Among the participants, 193 individuals developed CKD (estimated glomerular filtration rate under 60 ml/min/1.73m2) between cohort examinations 6 (1995-1998) and 8 (2005-2008, mean follow-up 9.7 years). They were age- and sex-matched to 193 control individuals free of CKD. A total of 154 urinary metabolites were measured using mass spectrometry, and the association between metabolites and CKD was examined using logistic regression. Next, we tested the genetic associations of each metabolite with an Illumina exome chip. Urinary glycine and histidine were associated with a lower risk of incident CKD with an odds ratio of 0.59 (95% confidence interval [CI] 0.43-0.80) and 0.65 (0.50-0.85) respectively, per one standard deviation increase in metabolite concentration. Follow-up in the Atherosclerosis Risk in Communities cohort confirmed the association of urinary glycine with CKD. In exome chip analyses, 36 single nucleotide polymorphisms at 30 loci were significantly associated with 31 metabolites. We surveyed exome chip findings for associations with known renal function loci such as rs8101881 in SLC7A9 coding for an amino acid transporter, which has been associated with a lower risk of CKD. We found this polymorphism was significantly associated with higher levels of lysine and NG-monomethyl-L-arginine (NMMA). Increased urinary lysine and NMMA were associated with a lower risk of CKD (0.73 [0.50-0.90] and 0.66 [0.53-0.83], respectively) in the univariate model. Thus, low urinary glycine and histidine are associated with incident CKD. Furthermore, genomic association of urinary metabolomics identified lysine and NMMA as being linked with CKD and provided additional evidence for the association of SLC7A9 with kidney disease.

Residual lifetime risk of chronic kidney disease.

BACKGROUND: An accurate estimation of the lifetime risk of chronic kidney disease (CKD) can aid in patient education while also informing the development of public health screening programs and educational campaigns. METHODS: Framingham Offspring Study participants were included if they were free of CKD (estimated glomerular filtration rate <60 mL/min/1.73 m2) at age 50 years and had at least two serum creatinine measures during follow-up (mean 16 years, 49 506 person-years). We estimated the lifetime risk of CKD to age 90 years adjusting for the competing risk of death in the overall cohort and in population subgroups with known CKD risk factors including hypertension, obesity and diabetes. RESULTS: Overall 3362 individuals (52% women) were included in the study. Mean age at study baseline was 54 years. By the end of the study, 729 individuals (21.7%) developed CKD and 618 (18.4%) died. At age 50 years, the cumulative lifetime risk of CKD was 41.3% [95% confidence interval (CI) 38.5-44.0]. The risk was increased in those with risk factors at baseline including diabetes (52.6%, 95% CI 44.8-60.4), hypertension (50.2%, 95% CI 46.1-54.3) and obesity (46.5%, 95% CI 41.1-52.0). For those individuals without any risk factors at baseline, the lifetime risk of CKD was lower (34.2%, 95% CI 29.4-39.0) relative to those with 1, 2 or 3 risk factors (45.0, 51.5 and 56.1% respectively, P < 0.01 for all compared with those with no risk factors). CONCLUSIONS: Four out of 10 individuals without CKD at age 50 years will eventually develop CKD. This risk is modified by the presence of hypertension, diabetes and obesity at baseline. This demonstrates the importance of early identification of CKD risk factors, to aid in patient education, and potentially to reduce the future risk of disease.

Length Polymorphisms in Heme Oxygenase-1 and AKI after Cardiac Surgery.

Heme oxygenase-1 (HO-1) catalyzes the degradation of heme, which may be involved in the pathogenesis of AKI. Length polymorphisms in the number of GT dinucleotide repeats in the HO-1 gene (HMOX1) promoter inversely associate with HMOX1 mRNA expression. We analyzed the association between allelic frequencies of GT repeats in the HMOX1 gene promoter and postoperative AKI in 2377 white patients who underwent cardiac surgery with cardiopulmonary bypass. We categorized patients as having the short allele (S; <27 GT repeats) or long allele (L; ≥27 GT repeats), and defined AKI as an increase in serum creatinine ≥0.3 mg/dl within 48 hours or ≥50% within 5 days, or the need for RRT. Compared with patients with the SS genotype, patients with the LL genotype had 1.58-fold (95% confidence interval, 1.06 to 2.34; P=0.02) higher odds of AKI. After adjusting for baseline and operative characteristics, the odds ratio for AKI per L allele was 1.26 (95% confidence interval, 1.05 to 1.50; P=0.01). In conclusion, longer GT repeats in the HMOX1 gene promoter associate with increased risk of AKI after cardiac surgery, consistent with heme toxicity as a pathogenic feature of cardiac surgery-associated AKI, and with HO-1 as a potential therapeutic target.

Excessive diagnostic testing in acute kidney injury.

BACKGROUND: The patterns, performance characteristics, and yield of diagnostic tests ordered for the evaluation of acute kidney injury (AKI) have not been rigorously evaluated. METHODS: We characterized the frequency of AKI diagnostic testing for urine, blood, radiology, and pathology tests in all adult inpatients who were admitted with or developed AKI (N = 4903 patients with 5731 AKI episodes) during a single calendar year. We assessed the frequency of abnormal test results overall and by AKI stage. We manually reviewed electronic medical records to evaluate the diagnostic yield of selected urine, blood, and radiology tests. Diagnostic yield of urine and blood tests was determined based on whether an abnormal test affected AKI diagnosis or management, whereas diagnostic yield of radiology tests was based on whether an abnormal test resulted in a procedural intervention. In sensitivity analyses we also evaluated appropriateness of testing using prespecified criteria. RESULTS: Frequency of testing increased with higher AKI stage for nearly all diagnostic tests, whereas frequency of detecting an abnormal result increased for some, but not all, tests. Frequency of detecting an abnormal result was highly variable across tests, ranging from 0 % for anti-glomerular basement membrane testing to 71 % for urine protein testing. Many of the tests evaluated had low diagnostic yield. In particular, selected urine and blood tests were unlikely to impact AKI diagnosis or management, whereas radiology tests had greater clinical utility. CONCLUSIONS: In patients with AKI, many of the diagnostic tests performed, even when positive or abnormal, may have limited clinical utility.

Genome-wide association study of kidney function decline in individuals of European descent.

Genome-wide association studies (GWASs) have identified multiple loci associated with cross-sectional eGFR, but a systematic genetic analysis of kidney function decline over time is missing. Here we conducted a GWAS meta-analysis among 63,558 participants of European descent, initially from 16 cohorts with serial kidney function measurements within the CKDGen Consortium, followed by independent replication among additional participants from 13 cohorts. In stage 1 GWAS meta-analysis, single-nucleotide polymorphisms (SNPs) at MEOX2, GALNT11, IL1RAP, NPPA, HPCAL1, and CDH23 showed the strongest associations for at least one trait, in addition to the known UMOD locus, which showed genome-wide significance with an annual change in eGFR. In stage 2 meta-analysis, the significant association at UMOD was replicated. Associations at GALNT11 with Rapid Decline (annual eGFR decline of 3 ml/min per 1.73 m(2) or more), and CDH23 with eGFR change among those with CKD showed significant suggestive evidence of replication. Combined stage 1 and 2 meta-analyses showed significance for UMOD, GALNT11, and CDH23. Morpholino knockdowns of galnt11 and cdh23 in zebrafish embryos each had signs of severe edema 72 h after gentamicin treatment compared with controls, but no gross morphological renal abnormalities before gentamicin administration. Thus, our results suggest a role in the deterioration of kidney function for the loci GALNT11 and CDH23, and show that the UMOD locus is significantly associated with kidney function decline.

The association between vitamin B12, albuminuria and reduced kidney function: an observational cohort study.

BACKGROUND: Variants in CUBN, the gene encoding cubilin, a proximal tubular transport protein, have been associated with albuminuria and vitamin B12 (B12) deficiency. We hypothesized that low levels of B12 would be associated with albuminuria in a population-based cohort. METHODS: We analyzed participants from the Framingham Heart Study (n = 2965, mean age 58 years, 53% female) who provided samples for plasma B12. Logistic regression models adjusted for covariates including homocysteine were constructed to test the association between B12 and prevalent albuminuria (UACR ≥17 mg/g [men] and ≥25 mg/g [women]) and reduced kidney function (defined as an eGFR < 60 ml/min/1.73 m(2), RKF). Because of a significant interaction between B12 and homocysteine in the prevalent RKF model (p = 0.005), the model was stratified by the median homocysteine levels. Logistic regression models were constructed to test the association between B12 and incident albuminuria and RKF. The results were replicated in 4445 participants from NHANES 2003-2004. RESULTS: Baseline B12 levels ranged from 50-1690 pg/ml. Elevated B12 was associated with prevalent albuminuria (OR 1.44 per 1 SD increase, 95% CI 1.10-1.87) and RKF (OR 1.83, 95% CI 1.30-2.60). However after stratifying by median homocysteine levels, this relationship remained only in the higher homocysteine stratum. There was no association between B12 and incident albuminuria (OR 1.17, 95% CI 0.79 - 1.73) or RKF (OR 1.45, 95% CI 0.97 - 1.88). In the NHANES cohort, elevated B12 was associated with RKF after full covariate adjustment (OR 3.06, 95% CI 2.30-4.08). There was no association with albuminuria. CONCLUSION: In participants with high baseline homocysteine levels, increased plasma B12 was associated with RKF.

Mid-adulthood risk factor profiles for CKD.

Early identification of CKD risk factors may allow risk factor modification and prevention of CKD progression. We investigated the hypothesis that risk factors are present ≥30 years before the diagnosis of CKD in a case-control study using data from the Framingham Offspring Study. Patients with incident CKD (eGFR≤60 ml/min per 1.73 m2) at examination cycles 6, 7, and 8 were age- and sex-matched 1:2 to patients without CKD at baseline (examination 5). CKD risk factors were measured at each examination cycle. Logistic regression models, adjusted for age, sex, and time period, were constructed to compare risk factor profiles at each time point between cases and controls. During follow-up, 441 new cases of CKD were identified and matched to 882 controls (mean age 69.2 years, 52.4% women). Those who ultimately developed CKD were more likely to have hypertension (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.23 to 2.51), obesity (OR, 1.71; 95% CI, 1.14 to 2.59), and higher triglyceride levels (OR, 1.43; 95% CI, 1.12 to 1.83) 30 years before CKD diagnosis, and were more likely to have hypertension (OR, 1.38; 95% CI, 1.07 to 1.79), higher triglyceride levels (OR, 1.35; 95% CI, 1.11 to 1.64), lower HDLc (OR, 0.89; 95% CI, 0.81 to 0.97), and diabetes (OR, 2.90; 95% CI, 1.59 to 5.29) 20 years before CKD diagnosis. These findings demonstrate that risk factors for CKD are identifiable ≥30 years before diagnosis and suggest the importance of early risk factor identification in patients at risk for CKD.

Sequencing of LRP2 reveals multiple rare variants associated with urinary trefoil factor-3.

Novel biomarkers are being investigated to identify patients with kidney disease. We measured a panel of 13 urinary biomarkers in participants from the Offspring Cohort of the Framingham Heart Study. Using an Affymetrix chip with imputation to 2.5 M single-nucleotide polymorphisms (SNPs), we conducted a GWAS of these biomarkers (n=2640) followed by exonic sequencing and genotyping. Functional studies in zebrafish were used to investigate histologic correlation with renal function. Across all 13 biomarkers, there were 97 significant SNPs at three loci. Lead SNPs at each locus were rs6555820 (P=6.7×10(-49); minor allele frequency [MAF]=0.49) in HAVCR1 (associated with kidney injury molecule-1), rs7565788 (P=2.15×10(-16); MAF=0.22) in LRP2 (associated with trefoil factor 3 [TFF3]), and rs11048230 (P=4.77×10(-8); MAF=0.10) in an intergenic region near RASSF8 (associated with vascular endothelial growth factor). Validation in the CKDGen Consortium (n=67,093) showed that only rs7565788 at LRP2, which encodes megalin, was associated with eGFR (P=0.003). Sequencing of exons 16-72 of LRP2 in 200 unrelated individuals at extremes of urinary TFF3 levels identified 197 variants (152 rare; MAF<0.05), 31 of which (27 rare) were nonsynonymous. In aggregate testing, rare variants were associated with urinary TFF3 levels (P=0.003), and the lead GWAS signal was not explained by these variants. Knockdown of LRP2 in zebrafish did not alter the renal phenotype in static or kidney injury models. In conclusion, this study revealed common variants associated with urinary levels of TFF3, kidney injury molecule-1, and vascular endothelial growth factor and identified a cluster of rare variants independently associated with TFF3.