Urinary Concentrations Research Articles

Associations between urinary concentrations of benzothiazole, benzotriazole, and their derivatives and lung cancer: A nested case-control study

Benzothiazole (BTH), benzotriazole (BTR), and their respective derivatives (BTHs and BTRs) are emerging environmental pollutants with widespread human exposure and oncogenic potential. Studies have demonstrated adverse effects of exposure to certain BTHs and BTRs on the respiratory system. However, no study has examined the associations between exposure to BTHs and BTRs and lung cancer risk. We aimed to examine the associations between urinary concentrations of BTHs and BTRs and the risk of lung cancer in the general population from Quzhou, China. We conducted a nested case-control study in an ongoing prospective Quzhou Environmental Exposure and Human Health (QEEHH) cohort, involving 20, 694 participants who provided urine samples during April 2019–July 2020. With monthly follow-up until November 2022, 212 lung cancer cases were recruited and 1:1 matched with healthy controls based on age and sex. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) of lung cancer risk associated with urinary BTHs and BTRs concentrations using conditional logistic regression models after controlling for potential covariates. We also examined effect modification by several covariates, including sex, socioeconomic status, smoking status, alcohol consumption, and dietary habit. Creatinine-corrected urinary BTH and 2-hydroxy-benzothiazole (2-OH-BTH) levels were significantly associated with the risk of lung cancer, after adjusting for a variety of covariates. Participants in the highest quartile of BTH had a 95% higher risk of lung cancer, compared with those in the lowest quartile (adjusted OR = 1.95, 95% CI: 1.08–3.49; p for trend = 0.01). Participants with higher levels of urinary 2-OH-BTH had an 83% higher risk of lung cancer than those with lower levels (adjusted OR = 1.83, 95% CI: 1.16–2.88; p for trend = 0.01). Exposure to elevated levels of BTH and 2-OH-BTH may be associated with an increased risk of lung cancer. These associations were not modified by socio-demographic characteristics.

Does the primary cilium elongation play a role in urine concentration?

Does the primary cilium elongation play a role in urine concentration?

Urinary calprotectin as a diagnostic tool for detecting significant bacteriuria

Pyuria in dipstick examination serves as the most widespread screening tool for urinary tract infections (UTI). The absence of pyuria, however, does not exclude UTI. We investigated the diagnostic value of urinary calprotectin, a mediator protein of the innate immune system, which is released by leukocytes, for the detection of UTI and compared it with dipstick pyuria. Since even low numbers of leukocytes in the urine significantly increase urinary calprotectin concentrations, calprotectin might be a more sensitive marker than pyuria detected by dipstick. All 162 patients were prospectively included and underwent a urine dipstick, urine culture, quantification of proteinuria and determination of calprotectin in the urine. Urinary calprotectin was determined using an enzyme-linked immunosorbent assay (ELISA). UTI was defined as urine cultures with detection of one or a maximum of two uropathogenic bacteria with ≥ 105 colony-forming units per millilitre (CFU/ml). Exclusion criteria were acute kidney injury, chronic renal insufficiency and tumors of the urinary tract. 71 (43.8%) patients had a UTI. Of the 91 patients without UTI, 23 had a contamination and 19 had evidence of ≥ 105 CFU/ml considered to be asymptomatic bacteriuria. The median calprotectin concentration in patients with UTI and pyuria was significantly higher than in patients with UTI and without pyuria (5510.4 vs. 544.7 ng/ml). In ROC analyses, calprotectin revealed an area under the curve (AUC) of 0.70 for the detection of significant bacteriuria. Pyuria in dipstick examinations provided an AUC of 0.71. There was no significant difference between these AUCs in the DeLong test (p = 0.9). In patients with evidence of significant bacteriuria but without pyuria, a significantly higher calprotectin concentration was measured in the urine than in patients with neither pyuria nor UTI (544.7 ng/ml vs 95.6 ng/ml, p = 0.029). Urinary calprotectin is non-inferior to dipstick pyuria in the detection of UTI.

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.

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.

N-ethylhexedrone: a very long and bad trip! A Case series.

N-ethylhexedrone (NEH) is a new cathinone derivative with, currently, low toxicocokinetic, and toxicocodynamic knowledge. We present 3 documented clinical cases of NEH intoxication with plasma, and urine concentrations. A thorough search for metabolites was performed. The 3 patients were admitted to the emergency department, and 2 out of the 3 were hospitalized for an extended period. While recovering from the drug effects, 12 to 24 hours after nasal intake of New Psychoactive Substance (NPS), the patients described the following disorders: anxiety, feelings of persecution, asthenia, anhedonia, abulia, psychomotor slowing, and loss of consciousness. NEH was identified in all samples by liquid chromatography-high resolution mass spectrometry (LC-HRMS), and quantified by liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS). Quantitative analysis showed decreasing concentrations over time: for case 1, from 97.2 (Day 1, D1) to 0.7 (Day 7, D7) µg/L for plasma, and from 724 (D1) to 0.5 (D7) µg/L for urine. NEH concentration of 7.9 µg/L was found in the plasma collected at admission for case 2. For case 3: concentrations ranging from 49 (D1) to 1.8 (D7) µg/L in plasma, and from 327.3 (Day 5, D5) to 116.8 (D7) µg/L in urine were found. NEH was no longer detected in the urine sample at Day 10. Elimination half-life was estimated at 19, and 28 hours in patients 1 and 3, respectively. Four metabolites were identified in blood and urine: reduced NEH, dealkyl-NEH, reduced dealkyl-NEH, and hydroxy-NEH. The cases presented highlight the long detectable lifetime of NEH. Characterization of the metabolites will allow better identification of the consumption of this drug. Serious adverse events can be observed after NEH consumption, as 2 out of 3 patients required intubation and ventilation. A syndrome of inappropriate antidiuretic hormone secretion (SIADH) was also diagnosed. Two out of the three cases are notable because of the number of samples collected and because NEH was the only drug of abuse detected.

Mechanism and clinical role of TIMP-2 and IGFBP-7 in cardiac surgery-associated acute kidney injury: A review.

Acute kidney injury (AKI) is a common postoperative complication, but there is still a lack of accurate biomarkers. Cardiac surgery-associated AKI is the most common cause of major-surgery-related AKI, and patients requiring renal replacement therapy have high mortality rates. Early diagnosis, intervention, and management are crucial for improving patient prognosis. However, diagnosing AKI based solely on changes in serum creatinine level and urine output is insufficient, as these changes often lag behind actual kidney damage, making early detection challenging. Biomarkers such as tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor-binding protein-7 (IGFBP-7) have been found to be significant predictors of moderate-to-severe AKI when combined with urine content analysis. This article reviews the mechanism of biomarkers TIMP-2 and IGFBP-7 in AKI and provides a comprehensive overview of the clinical effects of TIMP-2 and IGFBP-7 in cardiac surgery-associated AKI, including prediction, diagnosis, and progression.

#1973 Factors conditioning cisplatin nephrotoxicity

Abstract Background and Aims Cisplatin is an antitumor drug whose use is significantly limited by its nephrotoxicity. Knowledge of the factors that determine or condition the pathogenesis of cisplatin-induced AKI will help to prevent or reduce nephrotoxic outcomes and improve safety during cisplatin treatment. Specifically, we aimed to study the impact of different factors (dehydration, hypertension, age and combinations of the former) on a pre-clinical model of AKI induced by a low dose of cisplatin. Method Young Wistar rats, young spontaneously hypertensive rats (SHR), and aged Wistar rats were divided into two experimental groups: Blood and 24-hour urine samples were collected, and renal function (plasma creatinine, plasma urea and urine protein levels) and dehydration parameters (weight loss, skin elasticity, haematocrit, plasma osmolality, urine flow and urine concentration) were monitored for each animal at three different timepoints: basal time (B), at the end of the dehydration period (D0), and 4 days after cisplatin administration (D4, day of maximum kidney damage). Results After 48 h water deprivation, dehydration was evinced by loss of weight, reduced skin elasticity, increases in plasma osmolality and haematocrit, urine flow reduction and highly concentrated urine (with elevated density and osmolality). A single, low dose of cisplatin induced minimal loss of renal function in young normohydrated Wistar rats that was not worsened by previous acute dehydration resulting from 48 h water deprivation. Interestingly, although renal function was fully preserved when cisplatin was administered to hypertensive rats under normohydrated conditions, a cisplatin-induced AKI (with significant increases in plasma creatinine, plasma urea and proteinuria) was developed in hypertensive rats when animals were previously forced to dehydration. Aged Wistar rats with free access to drinking water showed an important loss of renal function after cisplatin administration (as supported by increases in plasma creatinine and urea concentration). This effect was significantly amplified when aged animals were dehydrated at the time of cisplatin administration. Conclusion Our results suggest that age is an important factor conditioning cisplatin nephrotoxicity. Hypertension or dehydration in fully competent young rats are not in itself significant risk factors for AKI. However, when dehydration is combined with other comorbidity (age or hypertension) the risk of cisplatin-induced AKI is significantly increased. In perspective, our animal models reproducing conditions of increased vulnerability to cisplatin-induced AKI provide useful tools not only for the identification of predictive biomarkers pre-emptively detecting individuals at high risk, but also to assess preventive strategies potentially useful for vulnerable individuals. This study was supported by Project PI21/01226, funded by Instituto de Salud Carlos III (ISCIII) and co-funded by the European Union, and a grant from the Consejería de Educación, Junta de Castilla y León (IES160P20), Spain, co-funded by FEDER funds. Noelia Diaz-Morales is recipient of a Juan de la Cierva-Formación postdoctoral contract (FJC2020-043205-I) funded by MCIN/AEI/10.13039/501100011033 and European Union “NextGenerationEU/PRTR”.

#2983 Correlation of microRNA expression with IgA nephropathy progression: preliminary results

Abstract Background and Aims IgA nephropathy (IgAN) is the most common cause of glomerulonephritis worldwide. IgAN is diagnosed based on the result of histopathological examination. The risk factors for disease progression primarily include the level of impairment of renal function at the time of diagnosis (GFR < 60 ml/min/1.73 m2), the presence of hypertension, daily administration of more than 1.0 g, and the occurrence of hematuria. MicroRNAs (miRNAs) are important regulators of gene expression. Their role has a significant impact on the proper functioning of the body, and disorders related to their expression can lead to the development of many pathological processes in the body. The study aimed to assess the dependence of microRNA expression on the stage of the disease in patients with IgA nephropathy. Method A study was conducted involving patients newly diagnosed with IgA nephropathy based on histopathological examination results. The expression of microRNA molecules (miR-146a, miR-155, miR-200b, miR-429) was determined in urine sediment and blood. The analysis focused on examining the relationship between microRNA expression and the stage of disease progression (proteinuria, renal parameters). Blood and urine tests were performed before the start of immunosuppressive treatment with glucocorticosteroids according to the Pozzi regimen. Results Twenty-seven patients were included in the study group- 14 women (51.9%) and 13 men (48.1%). Nephrotic-range proteinuria (>3000 mg/24 h) was observed in 5 patients (18.5%), while subnephrotic proteinuria was present in 22 patients (77.8%). Reserved kidney function (eGFR > 90) was found in 17 patients (63%). The exact distribution of results according to the stage of renal failure is given in the Table 1. Statistically significant positive correlation was found between serum creatinine concentration and miR-200b expression in urine (R = 0,398, p = 0,049). Initially, no statistically significant correlation was found between the expression of selected miRNA molecules and the degree of 24-hour proteinuria. Conclusion MiRNA molecules may be promising, non-invasive biomarkers widely used in clinical practice. Determining the viability of clinical use of microRNA molecules will require a panel of miRNAs or miRNAs used in combination with other biomarkers and clinical outcomes to improve diagnostic utility.

#2715 Towards precise prediction of prognosis in ADPKD: a comprehensive biomarker analysis

Abstract Background and Aims Determining prognosis in patients with autosomal dominant polycystic kidney disease (ADPKD) heavily relies on the height-adjusted total kidney volume (HtTKV) Mayo classification. This classification predicts kidney outcomes on a group level but lacks precision in individual patients. Recently, several urine and blood biomarkers have demonstrated prognostic value in ADPKD, independent of HtTKV and baseline eGFR. This study compares the prognostic value of various biomarkers to aid selection when developing novel risk stratification tools. Method Included were participants of the DIPAK studies with a follow-up duration of >1 year and ≥3 eGFR measurements. We excluded patients with diabetes mellitus and patients using tolvaptan or somatostatin analogues. At baseline, urine samples were analyzed for albumin, urea, creatinine, β2-microglobulin (β2-MG), monocyte chemotactic protein-1 (MCP-1), TmP/GFR (tubular maximum reabsorption rate of phosphate to GFR), and blood was drawn to measure creatinine, urea (for assessment of urinary-to-plasma urea ratio; UP urea), glucagon, fibroblast growth factor 23 (FGF-23) and copeptin. Albumin, β2-MG and MCP-1 were divided by urinary creatinine concentration to account for concentration effects. The cross-sectional and longitudinal association with baseline eGFR and eGFR decline over time was analyzed using multivariate linear regression and repeated measures linear mixed model regression. Furthermore, logistic regression models were tested to identify patients with rapidly-progressive disease (eGFR slope ≤ −3.0 ml/min/1.73 m2/year). Lastly, multivariate Cox regression analysis was conducted to evaluate the time to the combined endpoint of 30% decline in eGFR, reaching an eGFR ≤ 15 ml/min/1.73 m2, initiation of dialysis or receiving a kidney transplant. Results 565 patients were included with a mean age of 47 ± 11 years, eGFR of 64 ± 27 ml/min/1.73 m2 and HtTKV of 858 [IQR: 540, 1305] ml/m. During a mean follow-up of 5.2 ± 2.2 years, the mean eGFR decline was −3.38 ± 2.37 mL/min/1.73 m2/year. Of these patients, 283 (50.1%) had rapidly progressive disease and 267 (47.3%) reached the combined kidney endpoint. All biomarkers except glucagon were associated with baseline eGFR and eGFR decline over time after adjustment for established clinical risk factors for disease progression (sex, PKD mutation and baseline age and eGFR). After adjustment for the same covariates, albumin/creatinine, MCP-1/creatinine, FGF-23, UP-urea and copeptin were predictive of rapid disease progression. The area under the curve (AUC) value for predicting rapidly progressive disease for the Mayo HtTKV classification alone was 0.694, which could be improved to 0.766 (P < .001) by a risk prediction model that also included the aforementioned predictive clinical risk factors. The introduction of several biomarkers further improved this clinical model, including albumin/creatinine (AUC 0.794, p = 0.03), MCP-1/creatinine (AUC 0.804, p = 0.04) and copeptin (AUC 0.789, p = 0.05). Similar results were seen in multivariate Cox regression models after adjustment for covariates, with independent predictors of the combined endpoint being again albumin/creatinine (P < .001), MCP-1 creatinine (P < .001), copeptin (p = 0.012), but now also UP-urea (p = 0.008) and FGF-23 (P < .001). These findings appeared robust in subgroup analyses of 200 patients with Mayo HtTKV class 1C and 122 patients with early disease (age ≤ 40 years and eGFR ≥ 60 ml/min/1.73 m2 at baseline), in whom predicting prognosis is most challenging. Conclusion In patients with ADPKD, albumin/creatinine, MCP-1/creatinine, FGF-23 and copeptin are consistent predictors of kidney outcomes after adjustment for established clinical risk factors. Our data suggest that these biomarkers should be prioritized when developing novel multimarker models to enhance precision of risk prediction in ADPKD.

#3023 Dietary protein intake modulates the tubular handling of the uremic retention solute indoxyl sulfate

Abstract Background and Aims Nutritional intervention constitutes a key part of the clinical management of individuals with chronic kidney disease (CKD). The gut emerged as an important source of uremic retention solutes, including indoxyl sulfate, p-cresyl sulfate and TMAO among the others. Indoxyl sulfate (IS) is produced through the gut microbial fermentation of tryptophan into indole and its conversion into indoxyl sulfate in the liver. Previous authors hypothesised that higher amounts of gut microbial metabolites can be sensed by kidney's proximal tubule cells through the use of receptors and signaling pathways. Particular evidence points to the involvement of kidney Organic Anion Transporters’(OATs') in controlling the gut-kidney communication. According to the so-called remote sensing hypothesis, kidney tubular cells respond to uremic toxins plasma fluctuations altering the activity of OAT1. Few studies have investigated whether in CKD the protein content in the diet affects gut generation, plasma retention and excretion mechanisms of indolic uremic toxins including kidney cells OAT1 expression. Method Eighteen male Sprague-Dawley rats (Janvier, France) aged 7-8 weeks and weighing between 270 and 388 g were randomly assigned to a low protein (LP) diet (n = 10) or a high protein (HP) diet (n = 8) after undergoing a 5/6 nephrectomy to develop CKD. For each diet, a sham-operated control group (n = 7 and n = 8 correspondingly) was used. After 7 weeks, urine was collected, and 8 weeks after the disease was induced, euthanasia was performed. Samples of kidney and blood were taken. mRNA and protein expression of OAT1 were sought via qPCR and Western blot. Forty patients with CKD were recruited in a cross-sectional study investigating eating habits and uremic toxins levels. Eating habits were searched via a food diary. Protein and energy intake were therefore calculated. Blood and 48 h-urine were collected. Blood creatinine and urea were determined with standard laboratory techniques. Total plasmatic and urinary IS concentrations were measured using LC-MS/MS. The fractional excretion (FE) i.e. the percentage of IS excreted relatively to the kidney filtered load, was calculated to assess IS remote sensing. Results Rats with chronic kidney disease (CKD) had considerably higher plasmatic levels of IS (p < .001) than sham rats. Rats with CKD on an HP diet, however, did not differ in plasma IS from rats fed an LP diet (p = .63). On the other hand, CKD rats fed an HP diet showed a substantial rise in 24-hour urinary IS (p < .001). The FE of IS was significantly higher (p = .005) in CKD rats on a HP diet and correlated with 24 h-urinary IS (Spearman r = .51, p value=.03) and with protein intake (Spearman r = .52, p value=.03) in CKD rats. OAT1 mRNA and protein expression was significantly higher in CKD rats given a HP diet (p = .025 and p = .009, respectively). By dividing the CKD patients into two groups by the median of protein intake, the FE of IS was significantly higher (p = .018) in the patients consuming a larger portion of proteins. Conclusion A diet higher in protein content in 5/6 nephrectomized CKD rats as well as in CKD patients likely leads to an increased production of indole in the colon. This results in increased IS fractional excretion but unchanged IS plasma retention. These findings offer more evidence for the mechanisms behind the remote sensing and signaling of uremic toxins derived from indole. In summary, a low-protein diet is still advised for people with chronic kidney disease.

Association of urinary biomarkers of tobacco exposure with lung cancer risk in African American and White cigarette smokers in the Southern Community Cohort Study.

After accounting for smoking history lung cancer incidence is greater in African Americans than Whites. In the Multiethnic Cohort, total nicotine equivalents (TNE) are higher in African Americans than Whites at similar reported cigarettes per day (CPD). Greater toxicant uptake per cigarette may contribute to the greater lung cancer risk of African Americans. In a nested case-control lung cancer study within the Southern Community Cohort, smoking-related biomarkers were measured in 259 cases and 503 controls (40% White, 56% African American). TNE, the trans-3-hydroxycotinine:cotinine ratio, 4-(methylnitrosamino)-1-3-(pyridyl)-1-butanol (NNAL), mercapturic acid metabolites of volatile organic compounds, phenanthrene metabolites, cadmium, and (Z)-7-(1R,2R,3R,5S)-3,5-dihydroxy-2-[(E,3S)-3-hydroxyoct-1-enyl]cyclopenyl]hept-5-enoic acid (8-iso-PGF2α) were quantified in urine. Unconditional logistic regression was used to estimate the odds ratios and 95% confidence intervals for each biomarker and lung cancer risk. TNE, NNAL and cadmium were higher in cases than controls (adjusted for age, race, sex, body mass index (BMI) and CPD). Among cases, these levels were higher in African Americans compared to Whites. After accounting for age, sex, BMI and pack-years, a one-SD increase in log-TNE (OR=1.30; 95% CI: 1.10-1.54) and log-NNAL (OR=1.27; 95% CI: 1.03-1.58 with TNE adjustment) were associated with lung cancer risk. In this study, where NNAL concentration is relatively high, the association for log-TNE was attenuated after adjustment for log-NNAL. Smoking-related biomarkers provide additional information for lung cancer risk in smokers beyond smoking pack-years. Urinary NNAL, TNE and cadmium concentrations in current smokers, particularly African American smokers, may be useful for predicting lung cancer risk.

#2194 Targeted metabolomics analysis identifies a specific metabolomic profile in patients with early chronic kidney disease

Abstract Background and Aims The complex interconnections between various metabolites and the kidney play a major role in the pathogenesis of chronic kidney disease (CKD). Hence, by the assessment of the relationship between metabolites and the kidney, more accurate biomarkers could be discovered to prevent and detect CKD at an early stage. The primary goal of this study was to find new serum and urine biomarkers for the diagnosis of early CKD by conducting a metabolomic profiling through targeted metabolomics of both blood and urine in patients with CKD. Method This cross-sectional study comprised 80 patients with CKD who were categorized into six subgroups (G1-G6) based on their eGFR according to the KDIGO Guidelines. Additionally, 20 healthy individuals were included as healthy control participants (group C). Ultra-high-performance liquid chromatography coupled with electrospray ionization-quadrupole-time of flight-mass spectrometry was used to perform serum and urine metabolomic profiling. The 6 metabolites evaluated by this study were selected based on the results of a previous untargeted analysis research. Both blood and urine samples underwent multivariate analysis, which was subsequently followed by univariate analysis and quantitative analysis. Initially, the PLSDA score plot and VIP score were utilized. The application of the cross-validation procedure to the initial set of 6 molecules provided outstanding results, including high accuracy, high R² values, and a significant Q2 value. Hence, the model might be deemed as predictive. Random Forest analysis was utilized to conduct biomarker analysis and prediction. The specificity and sensitivity of the compounds identified as possible biomarkers were assessed using the Receiver Operating Characteristic (ROC) curve and the area under the curve (AUC). Results There were strong positive correlations between eGFR and serum levels of Arginine (p < 0.05) and L-Acetylcarnitine (p < 0.05). Of note, the amounts of L-Methionine, L-Phenylalanine, Kynurenic acid, and Indoxyl sulfate in serum showed a progressive increase from group C to subgroups G1-G5. Furthermore, L-Methionine, L-Phenylalanine, Kynurenic acid, and Indoxyl sulfate exhibited a negative correlation with eGFR (p < 0.05). In addition, there was a positive correlation between the levels of urine Arginine, L-Methionine, and L-Phenylalanine and eGFR (p < 0.05). Urine levels of Kynurenic acid, Indoxyl sulfate, and L-Acetylcarnitine were higher in groups G4 and G5, as compared to groups G1-G3b and C, respectively. The urinary concentrations of Indoxyl sulfate, Kynurenic acid, Indoxyl sulfate, and L-Acetylcarnitine exhibited a negative correlation with eGFR (p < 0.05). Conclusion The current study shows that serum and urinary metabolites levels in patients with CKD display an alteration in production, secretion, and excretion in all CKD stages. There was demonstrated a distinct metabolomic profile in the course of CKD which points to novel biomarkers useful for the diagnosis and progression evaluation of CKD from its early stages.

#2879 Residual kidney function is more than urinary output alone in PD patients: insights derived from tubular functional Na MRI of the kidney

Abstract Background and Aims Maintenance of a cortico-medullary concentration gradient (CMG) is required for urine concentration and is one of most important tubular functions. We have previously demonstrated that the CMG can be quantified in both healthy controls and patients receiving HD, using 23NaMRI of the kidney. Peritoneal dialysis (PD) patients, in general, are considered to have better preservation of residual renal function (RKF), than comparative haemodialysis (HD) patients. We aimed to investigate if this was evident with respect to functional imaging of the CMG, to explore the concept that glomerular and tubular function may be dichotomized in patients with chronic kidney disease (CKD) requiring maintenance dialysis. Method We conducted an exploratory pilot study for 8 PD patients and 21 HD patients. Patients were instructed to fast from midnight before scanning. Urines samples were collected to measure osmolarity after fasting and a first MRI scan- performed to acquire baseline anatomical and sodium images. All MR imaging was carried out on a GE MR750 3T (GE Healthcare, WI) instrument. A custom-built two-loop (18cm in diameter) butterfly radiofrequency surface coil tuned for 23Na frequency (33.786 MHz) was used to acquire renal 23Na images. Results PD participants were 60 ± 10 years old, 50% male, mean body mass index (BMI) was 26.7 ± 4.6 kg/m2 and dialysis vintage was 20 ± 13 months, mean creatinine and urea clearance was 12 ± 7 mL/min/1.73 m2; HD participants were well matched, 60 ±18 years old, 52% men, BMI 27 ± 6 kg/m2 and dialysis vintage was 33 ± 25 months respectively. Urinary osmolarity was 284 ± 66 mosm/L and 239 ± 72, p = 0.1; mean medulla to cortex ratio was 1.2 ± 0.2 and 1.2 ± 0.1, p = 0.2 between PD and HD participants respectively. 7/8 PD participants were able to perform 24 hrs urine collection. Mean urine volume was substantial at 1525 ± 594 mL. We found no correlation between urine volume and corticomedullary gradient (Fig. 1A). Fig. 2C illustrates a 75 year old male, with medulla to cortex ratio at 1, urine volume 2100 mL, CLcrUr 18 mL/min/1.73 m2 and Fig. 1C showed a 55 years old patients, male, medulla to cortex ratio at 1.4, urine volume 2100 mL, CLcrUr 18 mL/min/1.73 m2. Conclusion These results underscore residual kidney function currently estimated by urine volume provides an incomplete assessment. Despite PD patients retaining higher degrees of RKF than HD patients, as assessed by urinary volume and small solute clearance, both patient groups have very similar degrees of directly imaged tubular function. The clinical importance of a focus on functional tubular mass to outcomes in dialysis patients is currently under further investigation.

#1962 Development of triple-whammy induced pre-renal AKI is highly dependent on the hydration status

Abstract Background and Aims The concomitant use of diuretics, non-steroidal anti-inflammatory drugs (NSAIDs), and angiotensin system inhibitors is known as Triple Whammy (TW) and significantly increases the risk of acute kidney injury (AKI) due to a reduction in the glomerular filtration rate. Maintenance of hydration contributes to correct kidney perfusion, and effective renal haemodynamic regulation allows the kidneys to cope with everyday stressors and challenges, such as TW therapy. Interference with these adaptive mechanisms frequently occurs due to extrinsic (environmental conditions, lifestyle, drugs) or intrinsic (comorbidities, ageing) factors and may lead to dehydration, a negative body liquid balance with a high impact on health. Identifying modifiable risk factors that pose individuals at high risk of AKI following TW therapy is key for the search and prescription of preventive strategies in a personalized manner. The aim of this work was to study the role of hydration status on the renal effect of TW. Method Two-month-old male Wistar rats were divided into 3 experimental groups: Blood and 24-hour urine samples were collected at basal state (B), two days after water deprivation (D0), and two days after TW therapy (D2). Body weight was monitored during the experiment. Haematocrit was assessed from blood samples, and osmolality, concentration of creatinine (Jaffe reaction), and urea (Jung method) were determined in plasma. Urinary flow was recorded, and specific gravity, osmolality and creatinine concentration were measured in urine samples. Results Dehydration was observed after 48 h water deprivation, evidenced by a 12% weight loss and significant increases in haematocrit and plasma osmolality. As expected, during this dehydrated state rats excreted a very reduced volume of a highly concentrated urine with elevated levels of specific gravity and osmolality. No changes in renal function were observed after 48 h water deprivation, nor after TW treatment in fully hydrated rats. Administration of TW triggered significant alterations of the renal function, indicative of AKI, only in rats previously deprived of water for 48 h. These alterations were markedly increased when dehydration was partially sustained during the TW treatment by a 60% water restriction. Conclusion TW-induced AKI in young Wistar rats is facilitated when the hydration status worsens. In this sense, assessing hydration and implementing (re)hydration strategies may help to reduce or prevent TW-induced AKI. This study was supported by Project PI21/01226, funded by Instituto de Salud Carlos III (ISCIII) and co-funded by the European Union, and a grant from the Conserjería de Educación, Junta de Castilla y León (IES160P20), Spain, co-funded by FEDER funds. Noelia Diaz-Morales is recipient of a Juan de la Cierva-Formación postdoctoral contract (FJC2020-043205-I) funded by MCIN/AEI/10.13039/501100011033 and European Union “NextGenerationEU/PRTR”.

Urine high–sensitive troponin I in children cannot offer an applicable alternative to serum

IntroductionIn children, congenital heart defects represent the primary cause of increased serum troponin I. The elimination process of cardiac troponin I from the bloodstream and the factors influencing this process remain unknown. The objective of this study was to explore the role of troponin I as an indicator of cardiac damage in children both in serum and urine, a concept previously investigated in adults.MethodsOur prospective study involved 70 children under 24 months of age. The first group underwent ventricular septal defect repair, while the second group involved children who had undergone partial cavopulmonary anastomosis. For these groups, urine and serum troponin I were assessed on four occasions. The third group, consisting of healthy children, underwent a single measurement of urine troponin I.ResultsSerum troponin I values exhibited an expected elevation in the early postoperative period, followed by a return to lower levels. Significantly higher concentrations of serum troponin I were observed in the first group of children (p < 0.05). A positive correlation was found between troponin I in the first three measurements and cardiopulmonary bypass and aortic cross-clamping time. There was no discernible increase in urine troponin I directly related to myocardial damage; troponin I couldn't be detected in most urine samples.DiscussionThe inability to detect troponin I in urine remains unexplained. Potential explanatory factors may include the isoelectric point of troponin I, elevated urinary concentrations of salts and urea, variations in urine acidity (different pH levels), and a relatively low protein concentration in urine.

The chemical memory of smoking tobacco.

The concentration in urine of N-acetyl-hydroxy-propyl-cisteine (3HPMA), an acrolein metabolite, has been employed as a marker of the risk of illness of smokers and the relative concentration of creatinine has been evaluated to verify the effect of moving from the practice of burning tobacco to nicotine vaping. From the results concerning the urine samples of 38 subjects, collected from 2021 to 2023 and analyzed by LC-MS/MS, corresponding to 5 active smokers, 13 previously heavy smokers who replaced traditional tobacco by vaping, and 20 non-smokers, a dramatic reduction was found in 3HPMA/creatinine in urine. 3HPMA varied from values of 2150-3100 μg gcreatinine-1 to levels of 225-625 μg gcreatinine-1 found for non-smokers, with the time decay described by the equation y = 0.3661x2 - 94.359x + 6246.4 (R2: 0.757), providing a time of approximately 10 years for tobacco memory after the cessation of the consumption of burned tobacco.

Tenofovir, emtricitabine, lamivudine and dolutegravir concentrations in plasma and urine following drug intake cessation in a randomized controlled directly observed pharmacokinetic trial to aid point-of-care testing.

Poor adherence to ART and pre-exposure prophylaxis (PrEP) can impact patient and public health. Point-of-care testing (POCT) may aid monitoring and adherence interventions. We report the pharmacokinetics of tenofovir [dosed as tenofovir disoproxil (TDF) and tenofovir alafenamide (TAF)], emtricitabine (FTC), lamivudine (3TC) and dolutegravir (DTG) in plasma and urine following drug cessation to evaluate adherence targets in urine for POCT. Subjects were randomized (1:1) to receive DTG/FTC/TAF or DTG/3TC/TDF for 15 days. Plasma and spot urine were collected on Day 15 (0-336 h post final dose). Drug concentrations were quantified using LC-MS, and non-linear mixed-effects models applied to determine drug disposition between matrices and relationship with relevant plasma [dolutegravir protein-adjusted 90% inhibitory concentration (PA-IC90 = 64 ng/mL) and minimum effective concentration (MEC = 324 ng/mL)] and urinary thresholds [tenofovir disoproxil fumarate 1500 ng/mL]. Of 30 individuals enrolled, 29 were included (72% female at birth, 90% Caucasian). Median (range) predicted time to plasma dolutegravir PA-IC90 and MEC were 83.5 (41.0-152) and 49.0 h (23.7-78.9), corresponding to geometric mean (90%) urine concentrations of 5.42 (4.37-6.46) and 27.4 ng/mL (22.1-32.7). Tenofovir in urine reached 1500 ng/mL by 101 h (58.6-205) with an equivalent plasma concentration of 6.20 ng/mL (4.21-8.18). These data support use of a urinary tenofovir threshold of <1500 ng/mL (tenofovir disoproxil fumarate-based regimens) as a marker of three or more missed doses for a POCT platform. However, due to low dolutegravir concentrations in urine, POCT would be limited to a readout of recent dolutegravir intake (one missed dose).

Sex-specific associations of urinary mixed-metal concentrations with femoral bone mineral density among older people: an NHANES (2017–2020) analysis

BackgroundHeavy metal exposure is an important cause of reduced bone mineral density (BMD). Epidemiological studies focusing on the effects of mixed heavy metal exposure on BMD in middle-aged and older people are scarce. In single-metal studies, men and women have shown distinct responses of BMD to environmental metal exposure. This study therefore aimed to elucidate the association between mixed heavy metal exposure and BMD and to investigate whether it is sex-specific.MethodsData from the 2017–2020 National Health and Nutrition Examination Survey were selected for this cross-sectional study. The study used three statistical methods, i.e., linear regression, Bayesian kernel machine regression (BKMR) modeling, and weighted quartiles (WQS) regression, to explore the association between the urinary concentrations of 11 metals (barium, cadmium, cobalt, cesium, manganese, molybdenum, lead, antimony, tin, thallium, and Tungsten), either individually or as a mixture, and total femoral BMD.ResultsA total of 1,031 participants were included in this study. Femoral BMD was found to be higher in men than women. A significant negative correlation between the urinary concentrations of the 10 metals and femoral BMD was found in the overall cohort. Further gender sub-stratified analyses showed that in men, urinary metal concentrations were negatively correlated with femoral BMD, with cobalt and barium playing a significant and non-linear role in this effect. In women, although urinary metal concentrations negatively modulated femoral BMD, none of the correlations was statistically significant. Antimony showed sex-specific differences in its effect.ConclusionThe urinary concentrations of 10 mixed heavy metals were negatively correlated with femoral BMD in middle-aged and older participants, and this effect showed gender differences. These findings emphasize the differing role of mixed metal exposure in the process of BMD reduction between the sexes but require further validation by prospective studies.

Urine 5-Hydroxyindoleacetic Acid Negatively Correlates with Migraine Occurrence and Characteristics in the Interictal Phase of Episodic Migraine.

Although migraine belongs to the main causes of disability worldwide, the mechanisms of its pathogenesis are poorly known. As migraine diagnosis is based on the subjective assessment of symptoms, there is a need to establish objective auxiliary markers to support clinical diagnosis. Tryptophan (TRP) metabolism has been associated with the pathogenesis of neurological and psychiatric disorders. In the present work, we investigated an association between migraine and the urine concentration of TRP and its metabolites 5-hydroxyindoleacetic acid (5-HIAA), kynurenine (KYN), kynurenic acid (KYNA) and quinolinic acid (QA) in 21 low-frequency episodic migraine patients and 32 controls. We chose the interictal phase as the episodic migraine patients were recruited from the outpatient clinic and had monthly migraine days as low as 1-2 in many cases. Migraine patients displayed lower urinary levels of 5-HIAA (p < 0.01) and KYNA (p < 0.05), but KYN and QA were enhanced, as compared with the controls (p < 0.05 and 0.001, respectively). Consequently, the patients were characterized by different values of the 5-HIAA/TRP, KYN/TRP, KYNA/KYN, and KYNA/QA ratios (p < 0.001 for all). Furthermore, urinary concentration of 5-HIAA was negatively correlated with Migraine Disability Assessment score and monthly migraine and monthly headache days. There was a negative correlation between Patient Health Questionnaire 9 scores assessing depression. In conclusion, the urinary 5-HIAA level may be further explored to assess its suitability as an easy-to-determine marker of migraine.