Urinary Levels Research Articles

Case Report: Opposite Tumoral and Hormonal Responses to Low-dose Pasireotide in Cushing’s Disease

Background:: Pasireotide is a multireceptor somatostatin analogue approved for the treatment of patients with Cushing's disease (CD) who are ineligible or poor candidates for pituitary surgery. Here we present a patient with severe recurrent CD who was treated with pasiretide and showed opposite results between hormonal levels and pituitary tumour size. Case Presentation:: A 54-year-old woman was diagnosed with CD, a first surgical transsphenoidal procedure was performed at the time of diagnosis, and the disease recurred seven years later. She underwent a second transsphenoidal surgery, but despite apparent complete removal of the adenoma, the hypercortisolism worsened. Magnetic resonance imaging showed a tiny remnant of the adenoma adjacent to the cavernous sinus, and ketoconazole was started at a dose of 800 mg/day. Due to the persistence of pathological urinary free cortisol levels, 600 μg bid pasireotide was added. The combination therapy induced first normalisation of urinary free cortisol and later hypoadrenalism, so that ketoconazole was discontinued and pasireotide was maintained. A marked clinical improvement was achieved with pasireotide. Adrenal insufficiency persisted despite progressive tapering of the pasireotide dose to 150 mg once daily. Pituitary magnetic resonance imaging performed at 12 and 24 months during low-dose pasireotide treatment showed a few millimetres increase of the remnant. Conclusions:: This report suggests that CD Pas induces an opposite effect between hormonal profile and increase of pituitary tumor size. This peculiar phenomenon may be a consequence of the unusually low doses of pasireotide needed to control hormonal hypersecretion.

Diagnostic efficacy of urinary neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 for early detection of acute kidney injury in dogs with leptospirosis or babesiosis.

This study evaluates the diagnostic efficacy of urinary biomarkers, Neutrophil Gelatinase-Associated Lipocalin (uNGAL), and Kidney Injury Molecule-1 (uKIM-1), in identifying Acute Kidney Injury (AKI) in dogs affected with leptospirosis or babesiosis. Acute kidney injury was diagnosed based on the increase in serum creatinine levels above 0.3mg/dL within 48h and dogs were categorized according to AKI grades based on International Renal Interest Society guidelines. Traditional biomarkers (serum creatinine and blood urea nitrogen) and novel biomarkers like urinary NGAL and urinary KIM-1 levels were measured and compared to concentrations obtained in control dogs. Statistical analysis assessed significant differences (P < 0.01) across AKI grades, specifically noting elevated urinary NGAL and KIM-1 in IRIS grade I AKI (P < 0.001). The study highlights the diagnostic significance of urinary NGAL and KIM-1 as early indicators of renal damage, particularly valuable in non-azotemic AKI cases, offering promising markers for early AKI diagnosis in veterinary clinical settings. These biomarkers demonstrate clinical utility and underscore their potential for improving AKI management in veterinary medicine. Further validation studies involving larger cohorts and diverse etiologies of AKI are needed to confirm the diagnostic accuracy and clinical utility of urinary NGAL and KIM-1 in veterinary practice.

Frequent Dietary Multi-Mycotoxin Exposure in UK Children and Its Association with Dietary Intake

Mycotoxins are potent fungal toxins that frequently contaminate agricultural crops and foods. Mycotoxin exposure is frequently reported in humans, and children are known to be particularly at risk of exceeding safe levels of exposure. Urinary biomonitoring is used to assess overall dietary exposure to multiple mycotoxins. This study aims to quantify multi-mycotoxin exposure in UK children and to identify major food groups contributing to exposure. Four repeat urine samples were collected from 29 children (13 boys and 16 girls, aged 2.4–6.8 years), and food diaries were recorded to assess their exposure to eleven mycotoxins. Urine samples (n = 114) were hydrolysed with β-glucuronidase, enriched through immunoaffinity columns and analysed by LC-MS/MS for deoxynivalenol (DON), nivalenol (NIV), T-2/HT-2 toxins, zearalenone (ZEN), ochratoxin A (OTA) and aflatoxins. Food diaries were analysed using WinDiet software, and the daily intake of high-risk foods for mycotoxin contamination summarised. The most prevalent mycotoxins found in urine samples were DON (95.6% of all samples), OTA (88.6%), HT-2 toxin (53.5%), ZEN (48.2%) and NIV (26.3%). Intake of total cereal-based foods was strongly positively associated with urinary levels of DON and T-2/HT-2 and oat intake with urinary T-2/HT-2. Average daily mycotoxin excretion ranged from 12.10 µg/d (DON) to 0.03 µg/d (OTA), and co-exposure to three or more mycotoxins was found in 66% of samples. Comparing mycotoxin intake estimates to tolerable daily intakes (TDI) demonstrates frequent TDI exceedances (DON 34.2% of all samples, T-2/HT-2 14.9%, NIV 4.4% and ZEN 5.2%). OTA was frequently detected at low levels. When mean daily OTA intake was compared to the reference value for non-neoplastic lesions, the resulting Margin of Exposure (MoE) of 65 was narrow, indicating a health concern. In conclusion, this study demonstrates frequent exposure of UK children to multiple mycotoxins at levels high enough to pose a health concern if exposure is continuous.

Urinary polycyclic aromatic hydrocarbon metabolites and hyperlipidemia: NHANES 2007-2016.

The relationships between urinary polycyclic aromatic hydrocarbon (PAH) metabolites and hyperlipidemia have not been thoroughly studied. The primary goal of this research focused on investigating the linkage between PAH metabolite concentrations in urine and hyperlipidemia prevalence within US adults. A cross-sectional analysis was conducted using data from the 2007-2016 National Health and Nutrition Examination Survey (NHANES). Logistic regression models were used to assess correlations between urinary PAH metabolite levels and the risk of hyperlipidemia, while restricted cubic spline models were used to examine dose‒response relationships. Subgroup and interaction analyses were performed to further elucidate these associations. Weighted quantile sum (WQS) regression analyzed the cumulative impact of various urinary PAH metabolites on hyperlipidemia risk. This study included 7,030 participants. Notably, individuals in the highest quintile of urinary PAH metabolite concentrations exhibited a significantly elevated prevalence of hyperlipidemia, even after comprehensive adjustments (odds ratio [OR]: 1.33, 95% confidence interval [CI]: 1.01-1.75). Moreover, elevated levels of 1-hydroxyphenanthrene and 2-hydroxynaphthalene in the fourth quintile and 2-hydroxyfluorene in the third, fourth, and fifth quintiles demonstrated positive correlations with the prevalence of hyperlipidemia. These associations persisted across subgroup analyses. Additionally, a positive correlation between the urinary PAH metabolite mixture and hyperlipidemia (positive model: OR = 1.04, 95% CI: 1.00-1.09) was observed in the WQS model, and 2-hydroxynaphthalene showed the most substantial contribution. The cross-sectional analysis identified a significant correlation between urinary PAH metabolite and hyperlipidemia prevalence within the US demographic, with 2-hydroxynaphthalene being the predominant influencer. These findings underscore the need to mitigate PAH exposure as a preventive measure for hyperlipidemia.

Sleep characteristics in underweight young females across their menstrual cycles: A sleep-monitoring survey study with preliminary results.

This study investigated the association between underweight and sleep in young females across their menstrual cycles. A lifestyle-monitoring survey was conducted among 38 female university students aged 18-24 years in Japan from January to December 2023. Sleep data from 28 participants were analysed. Participants were categorized into underweight (n = 10) and control (n = 18) groups based on a baseline body mass index cut-off of 18.5 kg m-2. Sleep parameters were assessed using a daily sleep questionnaire, sleep sensor mats, and urinary melatonin metabolites across their menstrual cycles. The results indicated no significant differences in sleep patterns between the underweight and control groups or menstrual cycle phases, as assessed using both the daily sleep questionnaire and the sleep sensor mats. However, underweight participants experienced more difficulty maintaining sleep during the follicular phase. Body mass index significantly correlated with sleep efficiency (rs = 0.52) and wake after sleep onset (rs = -0.56). While urinary melatonin metabolite levels did not differ significantly between the groups or menstrual cycle phases, decreased levels during the luteal phase were more prevalent in the underweight group (7 of 10 participants) than in the control group (3 of 13 participants). This study suggests an association between underweight and sleep quality, especially nocturnal awakening, in young females. These findings underscore the importance of considering sleep quality in the management of underweight young females to improve their overall health outcomes.

Prenatal arsenic metabolite exposure is associated with increased newborn mitochondrial DNA copy number: evidence from a birth cohort study.

While mitochondria are susceptible to environmental detriments, little is known about potential associations between arsenic metabolites and mitochondria DNA copy number (mtDNAcn). We attempted to examine whether maternal urinary arsenic metabolite levels in different trimesters were related to neonatal cord blood mtDNAcn. We included 819 mother-newborn pairs embedded in an in-progress birth cohort survey performed from April 2014 to October 2016 in Wuhan, China. We determined maternal urinary arsenic species concentrations in different trimesters. We determined cord blood mtDNAcn using quantitative real-time polymerase chain reaction. In covariate-adjusted models, each one-unit increment of dimethylated arsenic (DMA) and total arsenic (TAs) in the third trimester was related to 8.43% (95% CI 1.13%, 16.26%) and 12.15% (95% CI 4.35%, 20.53%) increases in mtDNAcn, respectively. The dose-response trend with statistical significance was observed across tertiles of DMA and TAs in the third trimester with mtDNAcn (DMA percent changes (%Δ) = 25.60 (95% CI 6.73, 47.82), for the highest vs the lowest tertile (P = 0.02); TAs %Δ = 40.31 (95% CI 19.25, 65.10), for the highest vs the lowest tertile (P = 0.0002)). These findings may prove the relationships between prenatalarsenic species levelsand neonatalmitochondrial dysfunction.

#915 Role of VSIG4 in renal aging process

Abstract Background and Aims V-set Ig domain-containing 4 (VSIG4), known for its role in inflammation and fibrosis, is particularly interesting in the realm of chronic kidney diseases. However, its specific role in kidney aging, especially under the influence of diabetes, is not well understood. This study aims to elucidate the role of VSIG4 in the aging process of kidneys, particularly in the diabetes. Method This study used male db/db and db/m mice, beginning from the age of eight weeks and spanning 38 weeks. Urinary albumin and VSIG4 levels were assessed using 6-hour timed urine collections and ELISA. The intrarenal expression of VSIG4 and klotho were analyzed through qRT-PCR and Western blotting. Results Urinary albumin levels in db/db mice were significantly higher from 8 weeks onward compared to db/m mice. These levels increased progressively with age, peaking at 38 weeks. Similarly, urinary VSIG4 levels showed a significant initial increase in db/db mice, followed by a consistent rise with age. Interestingly, both urinary albumin and VSIG4 levels in db/m mice showed a sudden surge at 38 weeks. Notably, urinary VSIG4 levels paralleled these changes in albumin levels, with a correlation coefficient of 0.867 (p &amp;lt; 0.001). Intrarenal VSIG4 mRNA expression was markedly higher in diabetic mice and showed a significant increase at 16 and 38 weeks, with the 38-week levels being fivefold higher in db/m mice. The expression trends of VSIG4 protein were similar to its mRNA expression. The study also monitored intrarenal klotho expression to assess aging, which revealed a progressive decrease in both mRNA and protein levels with age. Conclusion This study highlights a significant upregulation of both urinary and intrarenal VSIG4 expressions in diabetic and non-diabetic mice. The strong association of urinary VSIG4 expression with albuminuria suggests its involvement in the renal aging process, potentially contributing to the pathogenesis of age-related kidney alterations.

#2897 Urinary CD44 levels in chronic kidney disease: a validation study

Abstract Background and Aims Proteinuria is the one of the main cause of kidney failure progression. There is inadequate data about protein components in urine and CKD severity. Our recent urinary proteomics study demonstrated the higher expression of CD44 in the urine proteome of healthy participants compared to CKD patients, arguing the protective role of CD44 in kidney health. However, the validation study needed to proof those differences in CD44 levels by ELISA tests in healthy participants and CKD patients. Therefore, we aimed to investigate urinary CD44 levels in our previously studied cohort of healthy controls and CKD patients using ELISA test. Method This study included 49 healthy participants and 88 early-stage CKD patients. Along with routine laboratory tests, 24 h collected urine samples were investigated using liquid chromatography-mass spectrometry (HPLC-MS) for proteomic analysis. Exponentially Modified Protein Abundance Index (emPAI) was used to estimate peptide count of proteins. Additionally, urinary CD44 levels were measured using ELISA kit to validate findings from proteomic study. Results A brief baseline characteristics of study population presented in Table 1. CKD group represented with lower eGFR, increased creatinine and higher proteinuria compared to healthy controls. Urinary CD44 levels were significantly higher in CKD group compared to healthy controls. Both CD44 levels measured by HPLC-MS and ELISA methods significantly positively correlated with eGFR levels (Table 2). Conclusion In this validation study, we compared the levels of CD44 measured by HPLC-MS and ELISA in healthy controls and CKD patients. We demonstrated that CD44 is overexpressed in urine samples of healthy people compared to CKD patients and may play a protective role in the kidney health. Further investigations needed to explain this finding in a different cohort and large number of CKD patients.

#2959 Correlation of urinary MCP-1 with different histopathological classes of lupus nephritis

Abstract Background and Aims Lupus nephritis (LN) affects almost two-thirds of Systemic lupus erythematosus (SLE) patients. Renal biopsy is the gold standard for the classification of LN. Minimally invasive techniques, as urinary biomarkers, are promising tools for the diagnosis and monitoring of SLE. This study aimed to determine urinary MCP-1 level association with different LN histopathological classes. Method This study included 40 patients with active lupus nephritis proteinuria &amp;gt;0.5 gm and/or active urinary sediment and/or decline in kidney function indicated for renal biopsy by the nephrology team. Morning urine samples were collected to measure MCP-1 level by enzyme-linked immunosorbent assay (ELISA). Full blood cell count, serum creatinine level, blood urea nitrogen (BUN) was collected. Biopsies were classified according to ISN /RPS, and biopsy results were correlated with MCP-1 level. We excluded patients with overlap syndrome, active infection, and malignancy. All the patients were diagnosed according to the American College of Rheumatology (ACR) diagnostic criteria. Results Mean age 28.75 ± 6.37 years. Female patients were 33 (82.5%) and 7 (17.5%) male patients. Mean creatinine was 2.71 ± 0.55 mg/dl in the active cases and 0.84 ± 0.10 mg/dl in the control group. The mean albumin was 3.1 ± 0.61 mg/dl in the active cases, and 4.05 ± 0.42 mg/dl in the control group. The mean eGFR was 56.14 ± 20.40 ml/min/1.73 m in the active cases, and 99.63 ± 6.90 40 ml/min/1.73 m in the control group. Our study showed a significant correlation between disease activity and urinary MCP-1 level. The Median MCP-1 level was 618.4 ng/l in patients with active LN and 120.05 ± 87.53 ng/l in patients with inactive LN with a sensitivity of 97.5% and specificity 95%. Level of urinary MCP-1 was highest in class IV with median of 998 followed by class III 567 then class V with median 357 ng/ml Conclusion Urinary MCP-1 level provided an auxiliary noninvasive tool to distinguish between different histopathological classes of active LN.

#1365 Clinical efficacy of tonsillectomy combined with steroid pulse therapy in IgA nephropathy

Abstract Background and Aims IgA nephropathy is the most common primary glomerulonephritis in the Asia–Pacific region, including Japan, and often leads to dialysis initiation. The etiology of IgA nephropathy remains unclear; however, focal infections such as chronic tonsillitis are proposed. Although tonsillectomy should not be performed for Caucasian IgA nephropathy patients, some Japanese studies reported that the combination of steroid pulse therapy with tonsillectomy (TSP) was more effective than steroid pulse therapy alone for the remission of urinary findings. However, the immunosuppressive treatment regimens vary among studies, and treatment effect of combination therapy in preventing renal functional decline is unclear. This study aimed to compare the efficacy of steroid pulse therapy alone versus TSP in improving the remission rate of urinary findings and preventing renal functional decline. Method This retrospective observational study included 116 patients diagnosed with IgA nephropathy based on renal biopsy and treated between January 1, 2010 and December 31, 2020 in Gifu University Hospital. TSP group underwent tonsillectomy received 0.5 g/day of methylprednisolone intravenously for 3 consecutive days at 1-3 weeks. TSP and steroid pulse therapy alone group had 83 and 33 patients, respectively. Of these, 25 patients per group were matched using propensity score matching based on clinicopathologic factors including age, urinary protein level, estimated glomerular filtration rate (eGFR), and the risk classification for progression to end-stage renal disease. The remission rate of urinary findings and the change in eGFR one year after treatment initiation were compared between the two groups. Remission of urinary findings was defined as a urinary protein level of &amp;lt;150 mg/day and &amp;lt;5 erythrocytes/high-power field in the urine sediment. Results The TSP and steroid pulse therapy alone groups did not significantly differ in baseline characteristics including median age (interquartile range) (58 [47–63] and 56 [49–68] years, respectively), female sex (9 and 7, respectively), mean eGFR (60 ± 20 and 63 ± 21 mL/min/1.73 m2, respectively), median urinary protein level (764 [440–1,472] and 990 [425–1,872] mg/day, respectively) (p &amp;gt; 0.05 for all). The remission rate of urinary findings was significantly higher in the TSP group than in the steroid pulse therapy alone group (72% vs. 20%; p &amp;lt; 0.001, χ2 test). Albeit statistically nonsignificant, the decline in eGFR was smaller in the TSP group than that in the steroid pulse therapy alone group (−1.5 ± 8.1 vs −3.7 ± 10.5 mL/min/1.73 m2, p = 0.416; t test). No severe side effect was observed in both treatment groups. Conclusion The higher remission rate of urinary findings observed in the TSP group compared to the steroid pulse alone group suggested that the addition of tonsillectomy to steroid pulse therapy was a clinically effective treatment for IgA nephropathy. Albeit not significant, the TSP group tended to have a smaller decline in eGFR reduction at one-year follow-up, indicating the need for further studies with long-term observation.

#68 Novel clinical application of urinary angiotensin-converting enzyme assay in renal sarcoidosis: a retrospective observational study

Abstract Background and Aims Renal manifestations of sarcoidosis are observed in approximately 1–5% and characterized mainly by granulomatous interstitial nephritis, which could lead to kidney failure. Angiotensin-converting enzyme (ACE) reflects the presence of granuloma; hence, serum ACE and tubular injury markers are measured in renal sarcoidosis (RS); however, they either have low sensitivity or low specificity. Although its practicality has not been established, the use of ACE levels in cerebrospinal fluid has been reported for neuro-sarcoidosis. Therefore, we hypothesized that urinary ACE could reflect granuloma presence in the kidneys and could be a disease-specific marker for RS. Method This was a single-center, retrospective observational study. We evaluated clinical characteristics and kidney biopsy findings from electronic medical record surveys and kidney biopsy specimens. The control groups included sarcoidosis without renal involvement (SAR-control) and tubulointerstitial nephritis without a sarcoidosis etiology (TIN-control). Serum and urinary ACE levels were measured, and urinary fractional excretion of ACE (FEACE) was investigated. Serum ACE assay and urinary ACE levels were measured using the colorimetric method with p-hydroxybenzoyl-glycyl-L-histidyl-L-leucine. A total of six patients (three with RS; one with sarcoidosis as controls; and two with TIN controls) with undetectable urinary ACE levels were excluded from the urinary ACE and FEACE analyses. Tubulointerstitial lesions were visually assessed for essentially normal (%), inflammatory cell infiltrates (%), tubular atrophy (%), and interstitial fibrosis (%) by several board-certified nephrologists, and analyzed the correlation of these lesions with each marker. Results This study included 18 patients with RS, 18 as SAR-control, and 10 as TIN-control. Serum ACE, urinary ACE, and FEACE levels in the RS group were significantly higher than those in the control groups. Receiver operating characteristic analysis identified FEACE and serum ACE levels as useful biomarkers for diagnosing RS among patients with both controls, respectively. In the RS group, FEACE was positively correlated with the degree of tubulointerstitial injury (r = 0.69, P = 0.0045), and the cutoff value of FEACE for diffuse tubulointerstitial injury (50.0% or more) was 0.39%, with a sensitivity and specificity of 100.0%. Furthermore, obvious positive correlations were observed among FEACE, inflammatory cell infiltrates (r = 0.53, P = 0.044), and interstitial fibrosis (r = 0.56, P = 0.029) in the RS group but not in the TIN-control. Conclusion Combination with serum and urinary ACE could help diagnose and assess disease severity among patients with RS.

#2641 MiR-200b induces ZEB1 mediated upregulation of Matriptase and affects expression of podocin

Abstract Background and Aims Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease and a predominant reason for renal failure. Evidence from previous research indicates that abnormal expression of microRNAs (miRs) links closely to the occurrence and progression of DKD. Methods Expression of miRs in urine samples from DKD patients and in cultured renal cells stressed with transforming growth factor beta 1 (TGF-β1) was evaluated by TaqMan assay. The emerging miR of interest and its downstream targets were analyzed in human renal sections, in cultured human podocytes and in zebrafish. Results Cell free urine screening showed increased abundance of miR-200b in samples from patients with DKD when compared to healthy controls. In situ hybridization confirmed expression of miR-200b in kidney specimens from DKD patients, but was not detected in healthy renal parenchyma. Transcriptome profiling of cultured human podocytes overexpressing miR-200b identified this miR as a regulator of the ZEB1 mediated matriptase (ST14)/ podocin pathway and found TGF- β1 stress to be upstream activators of miR-200b expression in these cells. Immunofluorescence analysis of kidney sections from DKD patients showed increased expression of ST14 and decreased expression of podocin when compared to healthy controls. Furthermore, injection of a miR-200b mimic in zebrafish larvae caused an upregulation of ST14 and was accompanied by phenotypic changes such as edema, proteinuria and podocyte effacement. Conclusion Our results show that miR-200b is expressed in glomeruli and found at elevated levels in urine of DKD patients. Overexpression of miR-200b in cultured podocytes and in zebrafish induces upregulation of matriptase, a serine protease previously shown to cleave podocin. The observed increase in matriptase and decrease in podocin levels in glomeruli from DKD patients, together with the effect of a miR-200b mimic on proteinuria and ultrastructure of the pronephros in zebrafish positions miR-200b as a key regulator that modulates matriptase overactivation in DKD and warrants further studies.

#2493 Podocyturia: a novel biomarker of ageing

Abstract Background and Aims Urinary podocyte shedding (podocyturia) is a biomarker of glomerular injury in young and old individuals. Podocyturia is associated with diabetes and hypertension, and it is an early indicator of systemic cardiovascular disease. Importantly, podocyturia has also been noted in healthy adults and may indicate physiologic podocyte turnover. Whether age is a predictor of podocyte loss, independently of diabetes and hypertension, is still unclear. The aim of this study was to examine the association between age and urinary podocin levels. Method This was a secondary analysis of data from 5 studies, including 868 individuals, 18-90 years of age. Data on urinary podocin mRNA levels was present on all subjects, as measured by CFX96 Touch™ RT-PCR detection system (Biorad, USA). Descriptive statistics, Chi-square test, ANOVA, and post hoc analysis were performed. Linear regression was conducted with gender, diabetes status, and hypertension status as covariates. Significance was set at p &amp;lt; 0.05. Results The mean age of the total sample was 55.10 ± 14.84 years; 46% were female, 26.4% had diabetes, and 37.9% had hypertension. There were significant differences in mean podocin levels by age group (F = 25.27, p ≤ 0.001) as follows. Podocin levels were significantly lower in Group 1 (age 18-35 years; 0.79 ± 0.67 million copies), compared to Group 2 (36-55 years; 2.21 ± 2.15 million copies) and Group 3 (over 56 years; 2.86 ± 3.18 million copies). Moreover, mean podocin levels differed significantly between Group 2 and Group 3 (p = 0.003). Age was a predictor of podocyturia, independently of diabetes and hypertension (p &amp;lt; 0.001). Conclusion Podocyturia was present in younger adults. There was a significant rise in podocyturia in middle-aged adults (36-55 years), denoting a transitional phase. There were higher podocyturia levels in older adults compared to the youngest and middle-aged adults. These differences in podocin by age were observed while accounting for diabetes and hypertension.

#648 Relationship between renal tubular damage, interstitial fibrosis and semaphorin class 3C

Abstract Background and Aims The detailed mechanism of interstitial fibrosis in CKD has not been clarified. In this study, we focused on semaphorin class 3C (SEMA3C), a secreted protein expressed in the renal tubules, that is involved in embryonic kidney development [1], and investigated the relationship between SEMA3C and renal tubular damage and interstitial fibrosis. Methods &amp;lt; Clinical research&amp;gt; We investigated the correlation between serum SEMA3C concentration and the renal tubular damage marker urinary β2 microglobulin (β2MG) concentration in the 191 patients who underwent kidney biopsy from 2017 to 2021 at Yamagata University. &amp;lt; In vivo study&amp;gt; We generated proximal tubule-specific SEMA3C knockout mice (PT-SEMA3C KO) from male mice (C57BL/6) using the Cre/loxP system. The PT-SEMA3C KO group and control group were fed a 0.2% adenine diet for 5 weeks to induce CKD. The area of interstitial fibrosis/tubular atrophy (IFTA) region was assessed by Masson-Trichrome staining. Results &amp;lt; Clinical research&amp;gt; The median age of the patients was 54 (IQR 38-68) years, 94 men and 97 women. Median serum SEMA3C concentration was 0.14 (IQR 0.07-0.35) ng/ml. Median urinary β2MG levels was 0.22 (IQR 0-1.79) mg/gCr. Spearman's correlation analysis showed a significant negative correlation between serum SEMA3C and urinary β2MG levels (r=-0.208, P=0.005), but no correlation between eGFR and Urinary protein/ creatinine. &amp;lt; In vivo study&amp;gt; IFTA region was 5.6% in the control group, compared to 11.2% in the PT-SEMA3C KO group (p=0.031). Interstitial fibrosis was significantly suppressed in the PT-SEMA3C KO mice (Fig. 1). Conclusion Our clinical and in vivo results indicate that serum SEMA3C is associated with renal tubular damage and interstitial fibrosis.

#553 Renal tubular damage is an independent risk factor for all-cause and cardiovascular mortality in a community-based population: the Takahata Study

Abstract Background and Aims Renal tubulointerstitial damage is a risk for renal failure. However, the association between renal tubulointerstitial damage and all-cause and cardiovascular mortality in the general population remains unclear. In this prospective cohort study, we examined this point using urinary β2-microglobulin/creatinine ratio (UBCR) as a marker of renal tubulointerstitial damage in the general Japanese population. Methods We examined the association between UBCR values at entry and all-cause and cardiovascular mortality during the follow-up period (median 9.2 years) in 3 427 residents (mean age 62.5 years, 45.1% male, mean eGFR 81.6 ml/min/1.73 m², ≥1+ protein 4.4%) of Takahata Town in Japan. Results Study participants were divided into two groups (low &amp;lt; 300 μg/gCre, high ≥300 μg/gCre) based on UBCR at entry. Kaplan-Meier analysis showed a significantly higher incidence of all-cause and cardiovascular mortality in the high UBCR group (Log-rank P &amp;lt; 0.01). A multivariate Cox proportional hazards analysis adjusted for age, sex, eGFR, urinary protein level, comorbidities, smoking status, and other background factors showed a hazard ratio of 1.47 (95% CI 1.09-2.00, P = 0.01) for all-cause mortality and a hazard ratio of 1.82 (95% CI 1.06-3.12, P = 0.03) for cardiovascular death in the high-UBCR group. The addition of high UBCR to conventional risk factors, including eGFR and urinary protein level, significantly improved the net reclassification improvement (NRI) for all-cause and cardiovascular mortality (P &amp;lt; 0.01). Conclusions UBCR, a marker of tubulointerstitial damage, was identified as a risk factor for all-cause and cardiovascular mortality in the general population independent of eGFR and urinary protein levels.

#2308 The effect of Dapagliflozin on albuminuria and biomarkers associated with renal function in patients with β-thalassemia and/or sickle-cell disease

Abstract Background and Aims Patients with β-thalassemia present already from the 1st year of life with serious anemia thus needing regular blood transfusions in order to attain normal hemoglobin levels. Chronic anemia, iron overload and the use of iron chelating agents have been associated with renal dysfunction. In sickle-cell syndromes, which include sickle-cell anemia and sickle-cell trait, patients present with typical kidney functional and structural defects, resulting in urinary concentrating defects, distal nephron dysfunction and albuminuria. Sodium–glucose cotransporter-2 inhibitors (SGLT-2i) have shown beneficial effects on renal outcomes in large clinical trials with the added benefit of a substantial decrease in albuminuria. The aim of this prospective, non randomized open label study is to investigate the effect of Dapagliflozin at a dose of 10 mg daily on albuminuria and the overall progression of CKD in patients with β-thalassemia and/or sickle-cell disease undergoing regular blood transfusions. Method In this study we included adult patients undergoing regular blood transfusions with a baseline albuminuria of ACR&amp;gt;30 mg/gCr (assessed with a spot urine sample) who received treatment with Dapagliflozin, a second group with no albuminuria that did not receive treatment and a group of adults with no kidney disease (Controls). In all patients renal function biomarkers were measured in urine and serum with commercial ELISA kits (NGAL and uPAR in serum, MMP9 and KIM-1 in urine), while in patients that received Dapagliflozin additional measurements of ACR and eGFR (CKD-EPI formula) were performed after 3 months of treatment initiation. Results In this study we included 16 patients (7 males) with β-thalassemia and/or sickle-cell disease with ACR&amp;gt;30 mg/gCr, 35 patients (17 males) with β-thalassemia and/or sickle-cell disease without albuminuria and 20 controls (13 males). Patients that received Dapagliflozin showed a significant reduction in albuminuria three months post-initiation of treatment (ACR: 0.52 ± 1.2 vs. 0.3 ± 0.68 mg/g, p=0.006) while kidney function showed a slight non-significant reduction (eGFR: 99.3 ± 21.7 vs. 94.7 ± 28.9 ml/min/1.73m2, p=0.36). Concerning the urine and serum biomarkers of tubular dysfunction, inflammation and kidney disease progression, all were significantly increased in patients with β-thalassemia and/or sickle-cell disease in comparison to controls (Table 1). In patients that received treatment with Dapagliflozin, NGAL, MMP-9 and suPAR at 3 months post-treatment initiation did not show any significant reduction (Table 2). Conclusion Patients with β-thalassemia and/or sickle-cell disease show increased urine and serum levels of kidney damage biomarkers in comparison to healthy controls. Treatment of these patients with Dapagliflozin for 3 months has a significant effect in albuminuria reduction while it does not alter urine and serum levels of these biomarkers.

#887 Complement biomarkers in IgA nephropathy and IgA vasculitis with renal involvement: can urine rather than blood be the answer?

Abstract Background and Aims IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide. Dysregulation of the complement system is considered a part of the pathogenesis and can occur both in the circulation and locally in the kidney. Despite this, most studies have focused on complement biomarkers in the blood, rather than in urine. Our aim was to evaluate a wide range of complement-related proteins in blood and urine at diagnosis and their association with disease activity in biopsy findings, proteinuria, and outcome. We added PTX-3, a protein expressed in activated endothelial cells, which can be both produced by and activate mesangial cells in IgAN and has a function in all three complement pathways. Adult-onset IgA vasculitis with renal involvement (IgAVN) shares many similarities with IgAN and cannot currently be distinguished by kidney biopsy or any established biomarker. We therefore also aimed to compare the same biomarkers between these two disorders. Method In a Swedish cohort of 96 patients with IgAN (n = 65) and IgAVN (n = 31), who had been followed prospectively for a median of 10.8 years, we performed the following analysis in plasma and urine in samples stored at the time of kidney biopsy. Analyses in plasma (p-) included C3bc, C4c, C5b-9, MASP2, MASP3, MAP1, FCN 1-3, MBL, CL11 and PTX-3 and in urine (u-) C3bc, C4c, C5b-9, MASP3, FCN2, FCN3, MBL and PTX-3. An in-house developed sandwich ELISA was used for all analyses. Kidney biopsies were classified according to the Oxford MEST-C score, describing (simplified for this small cohort) the presence vs absence (1 vs 0) of mesangial proliferation (M), endocapillary proliferation (E), segmental sclerosis (S), tubular atrophy/interstitial fibrosis (T) and crescents (C). Severe outcome was defined by a combination of an eGFR slope &amp;gt; 2.5 ml/min/1.73 m2 per year or end stage kidney disease. For statistical analysis, Mann-Whitney U test was performed for comparison between independent groups, Chi squared test and Fisher's test for categorical variables and Spearman's ranks test for correlation analysis. Median values are presented without IQR for this abstract. Results Urine samples were available in 59 patients (IgAN n = 39, IgAVN n = 20). Patients with detectable u-MBL (28.9%) and u-C5b-9 (27.1%) had higher levels of proteinuria than those with undetectable levels (1.5 g/d vs 0.71g/d; p = 0.009 and 2.3 g/d vs 0.7 g/d respectively; p &amp;lt; 0.001). Lower eGFR (71 ml/min/1.73 m2 vs 88 ml/min/1.73 m2; p = 0.034) were observed if u-C5b-9 was measurable. Detectable levels of u-PTX-3 and u-MBL were more often found in the presence of M1 vs M0 (53% vs 20%; p = 0.022 and 47% vs 12.5%; p = 0.011), E1 vs E0 (55% vs 14%; p = 0.001 and 40% vs 11%; p = 0.020) and C1 vs C0 (56% vs 11%; p = 0.003 and 44% vs 11%; p = 0.012). No differences in proteinuria or eGFR were seen in patients with or without detectable u-PTX-3. The degree of proteinuria was positively correlated to the levels of u-C3bc (r = 0.33; p = 0.011) and u-C4c (r = 0.39; p &amp;lt; 0.001). U-C4c levels were higher in patients with M1 vs M0 (54.4 Au/mL vs 23.8 Au/mL; p = 0.037) and T1 vs T0 (53.2 Au/mL vs 23.8 Au/mL; p = 0.034). Concerning the analyses in plasma (n = 95), lower p-MASP3 and p-CL11 levels were correlated with lower eGFR (r = 0.29; p = 0.004 and r = 0.31, p = 0.002). Moreover, lower p-MASP3 levels were detected in patients with E1 vs E0 (2918 ng/mL vs 3404 ng/mL; p = 0.002) and C1 vs C0 (3053 ng/mL vs 3427 ng/mL; p = 0.015). Both p-C5b-9 (13.3 Au/mL vs 8.2 Au/mL; p = 0.001) and p-FCN 1 (395 ng/mL vs 289 ng/mL; p = 0.001) were higher in patients with C1 vs C0. No single complement-related protein was associated with severe outcome, and no statistically significant differences in plasma or urine levels between patients with IgAN and IgAVN were observed. Conclusion Increased urinary levels of MBL and PTX-3 could be potential biomarkers of disease activity in both IgAN and IgAVN, whereas excretion of C5b-9 might be more unspecific and associated with chronic damage. However, these results need to be confirmed in larger and more ethnically diverse cohorts. The impact of treatment on these potential biomarkers for disease activity need to be evaluated in longitudinal studies.

#2830 Treatment of primary and secondary distal renal tubular acidosis with a prolonged release formulation of potassium citrate and potassium bicarbonate

Abstract Background and Aims Distal renal tubular acidosis (dRTA) is a rare kidney disease. It can be inherited, i.e. primary (PdRTA), or acquired i.e. secondary (SdRTA). Secondary dRTA is more prevalent in the adult population and is usually caused by underlying autoimmune diseases (e.g. Sjogren syndrome). Both forms of dRTA are characterized by alkaline urine, kidney stone formation, nephrocalcinosis, chronic kidney disease, while metabolic acidosis can be variable. The treatment is based on the substitution of alkali substances. Our clinical study aims to describe a cohort of adult dRTA patients (both PdRTA and SdRTA) treated for 18 months by a prolonged-release alkalizing formulation of potassium citrate and potassium bicarbonate, in terms of electrolyte disbalance correction, metabolic control, nephrolithiasis complications and kidney function. Method Data from seven patients with dRTA (3 with PdRTA and 4 with SdRTA, mean age 44 years, women 71%) taking prolonged-release alkalizing formulation of potassium citrate and potassium bicarbonate in our center, were retrospectively collected and analyzed. The patients were previously treated with alkalizing agents (mostly sodium bicarbonate and potassium citrate). Patients were followed up for up to 18 months after inducing prolonged-release alkalizing formulation of potassium citrate and potassium bicarbonate was introduced. Kidney function, metabolic acidosis control (serum bicarbonate), serum electrolytes, urinary calcium excretion, and urinary citrate were measured. Nephrolithiasis complications and patient compliance were also evaluated. The urine and blood samples were analyzed two weeks after introducing the new drug and every 3 months afterward. Data are presented as mean ± standard error of the mean. Student T-test was used to calculate p values. Results The patients were taking on average 48 mEq of the drug (range 32-72 mEq), the dosage remained the same during the follow-up period (p = 0.365). The average follow-up period was 10 months (range 3-18 months). The metabolic acidosis was well controlled (serum bicarbonate was 24 ± 1.71 mmol/l at baseline, 24.4 ± 1.5 mmol/l at the end of follow-up, p = 0.680). Kidney function remained stable (GFR 73.5 ± 22.67 ml/min/1.73 m2 at baseline, 73 ± 22.69 ml/min/1.73 m2 at the end, p = 0.977). Serum potassium was also well controlled (4.07 ± 0.45 mmol/l at baseline, 4.32 ± 0.40 mmol/l at the end, p = 0.344), as well as calcium in 24-hour urine (2.75 ± 0.59 mmol/24-hour urine at baseline, 2.35 ± 0.12 mmol/24-hour urine at the end, p = 0.222). Urinary citrate levels (calculated as citrate/creatinine ratio) remained in the lower part of the reference range during the follow-up period (103.3 ± 68.3 mmol/mol at baseline, 114.6 ± 64.9 mmol/l at the end, p = 0.775). Two patients had acute renal colic caused by nephrolithiasis, without the need for surgical intervention. Safety and adherence to treatment remained good with no gastrointestinal side effects, one patient discontinued the drug due to headaches. Conclusion Our data show that treatment with a prolonged-release alkalizing formulation of potassium citrate and potassium bicarbonate in adult dRTA patients can achieve good control of metabolic acidosis and electrolyte disbalance with stable kidney function without the need to escalate the dose of the drug during the follow-up period. The adherence to the treatment remained good with no gastrointestinal side effects.

#1801 Gut dysbiosis contributes to TMAO accumulation in CKD

Abstract Background and Aims Chronic kidney disease (CKD) patients face a substantial morbidity risk, especially related to cardiovascular complications. The imbalance of circulating metabolites influences inter-organ crosstalk and disease pathophysiology. In this regard, metabolites of microbial origin have gained increasing attention. Trimethylamine N-oxide (TMAO) originates from microbial Trimethylamine (TMA) metabolism and is found at high concentrations in the blood of CKD patients. A high TMAO concentration is known to be an independent risk factor for cardiovascular disease. This study aims to investigate the extent to which high concentrations of TMAO in the blood are due to increased bacterial production or are mainly a consequence of impaired renal clearance. Methods We used existing biomaterials and clinical data of a pediatric CKD cohort, consisting of patients enrolled at CKD stage G3-5, including G5 patients treated with hemodialysis (HD), as well as patients after kidney transplantation (KT) and individuals with normal kidney function. We analyzed TMAO in plasma and urine samples using LC-MS/MS and developed a novel gene targeting assay (GTA) that quantifies the abundance of the bacterial target genes (CutC, CntA) encoding for the key enzymes of microbial TMA synthesis in each fecal sample. Results Plasma TMAO levels were stage-dependently elevated in CKD, with HD patients showing the highest levels (75 ± 46 µmol/l). While urinary TMAO levels were lower in the CKD groups, TMAO/creatinine ratios and fractional excretion were not significantly different in CKD compared to controls. Fecal microbial gene abundance of both CutC and CntA genes was elevated across CKD stages and correlated with both plasma TMAO levels and eGFR. Although KT patients exhibited an eGFR range comparable to controls, they still showed higher plasma TMAO levels and elevated TMAO-associated gene abundances. In a regression analysis, this gene abundance was associated with plasma TMAO independent of eGFR in a model adjusted for age, sex, and BMI. Using a likelihood ratio test, we showed that adding fecal microbial gene abundance to the model provided a significantly better fit compared to only eGFR, age, sex, and BMI. Conclusion Our data indicate that the production of TMA by intestinal bacteria contributes significantly to the accumulation of TMAO in patients with CKD and after kidney transplantation. This finding opens the possibility for new potential interventions in the management of patients with CKD.

#683 Utility of urinary soluble CD163 as a novel biomarker for the detection of IgA nephropathy

Abstract Background and Aims IgA nephropathy (IgAN) is an immune mediated disease and a leading cause of biopsy proven glomerulonephritis (GN) worldwide. CD163 is a membrane protein localised on the surface of monocytes and macrophages. Its soluble form, sCD163, produced by enzymatic splitting of the ectodomain of inflammatory cells when activated, is found in increased concentrations in acute inflammatory diseases such as sepsis and vasculitis. Urinary sCD163 levels have also been reported to be a useful biomarker of glomerular inflammation in lupus nephritis (LN) and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Yet, few studies have evaluated the role of urinary sCD163 as a biomarker in IgAN, and comparing it across different GN subtypes. This study aims to explore the utility of urinary sCD163 as a non-invasive biomarker for IgAN, and across different immune mediated GN types. Method This is a retrospective and prospective cohort study from a single tertiary hospital. Frozen urine samples from patients with GN and healthy controls from the Asian Kidney Disease Study and Singapore Kidney Function Study respectively were utilised for the retrospective cohort. The prospective cohort consists patients with biopsy-proven IgAN recruited from May to December 2023 with informed consent taken. Urinary sCD163 was measured using enzyme-linked immunosorbent assay (ELISA). Univariate analyses were performed and urinary sCD163 values were plotted on receiver-operating characteristic (ROC) curve and the area under the curve (AUC) was calculated. This study obtained Institutional Ethics Board Approval (DSRB 2022/00698). Categorical variables were represented by n (%). Continuous variables with a parametric distribution were represented by their means ± standard deviation, non-parametric variables were expressed as their medians with interquartile ranges. Chi-square test and ANOVA were performed between categorical variables, while a student's t-test was performed for continuous variables. P-value of &amp;lt; 0.05 was taken as statistically significant. A ROC curve was performed for sCD163 values in IgAN and controls, and the AUC calculated. Results In total, urine samples of 59 subjects were analysed (IgAN n = 10; LN n = 5; healthy controls n = 44). There were 30 male subjects (50.8%) and 29 female subjects (49.2%). Median age was 41.0 (IQR 31.0-52.0) years. Median serum creatinine was 78.0 (IQR: 60.0-91.0) µmol/L. Mean urine sCD163 value was 0.32 (±0.19) ng/ml. There were no baseline differences in demographics, comorbidities and medication between groups. Prospective cohort patients with IgAN were more likely to have received steroids (p = 0.03), and there were no patients of the Malay Ethnicity in the prospective cohort (p = 0.05). Median urine protein (g/day) in IgAN was 0.66 (IQR 0.16 to 3.29)¸ 0.159 in LN (IQR 0.09 to 0.26) and 0.12 in controls (IQR 0.07 to 0.20). Using Mann-Whitney U test to compare median proteinuria between IgAN and controls showed significant difference (p = 0.001), whereas median proteinuria between IgAN and LN was not statistically significant (p = 0.08). On univariate analysis compared to healthy controls, IgAN patients had a significantly higher serum creatinine (p = 0.04), compared to LN patients against controls (p = 0.30). Urine sCD163 levels were significantly higher in IgAN patients compared to controls (0.54 ± 0.26, p = 0.02). Patients with LN do not have a significant urinary sCD163 level difference compared to controls (0.21 ± 0.20, p = 0.40), which also correlates with creatinine and degree of proteinuria. There were no other significant baseline differences against controls. On the ROC curve for IgAN patients, urine sCD163 of 0.38 ng/ml has a 70% sensitivity, and 75% specificity in distinguishing IgAN against controls (AUC 0.77; 95% CI: 0.59-0.96, p = 0.008). For LN, urine SCD163 did not distinguish between LN and controls (AUC 0.29; 95% CI: 0.000-0.58, p = 0.12). Conclusion Urine sCD163 is elevated in patients with IgAN compared to controls and LN. Urine sCD163 is useful in the diagnosis of IgAN. A urine sCD163 level of 0.38 ng/ml has a 70% sensitivity and 75% specificity in identifying IgAN against healthy subjects.