Do serum and urinary concentrations of kidney injury molecule-1 in healthy newborns depend on birth weight, gestational age or gender?

Urinary biomarkers indicate pediatric renal injury among rural farming communities in Sri Lanka

Pediatric renal injury is an emerging health concern in communities affected by chronic kidney disease of uncertain etiology (CKDu). Early detection of susceptibilities through highly sensitive and specific biomarkers can lead to effective therapeutic and preventive interventions against renal diseases. Here, we aimed to investigate the utility of kidney injury molecule (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) in early detection of renal abnormalities in selected pediatric communities in Sri Lanka. The study areas were stratified as CKDu endemic, emerging, and non-endemic based on the prevalence of CKDu, and a total of 804 school students (10–18 years of age) participated in the study. The median (IQR) urinary KIM-1 levels of the participants were 0.193 (0.026–0.338), 0.082 (0.001–0.220) and 0.040 (0.003–0.242) ng/mgCr for CKDu endemic, emerging and non-endemic regions respectively. Participants from CKDu endemic regions reported elevated (p < 0.0001) urinary KIM-1 expression compared to those from the other regions. The median (IQR) NGAL levels in participants from CKDu endemic (2.969; 1.833–5.641), emerging (3.374; 1.766–6.103), and non-endemic (3.345; 1.742–5.128 ng/mgCr) regions showed no significant difference. Also, urinary albumin-creatinine ratio (UACR) showed no significant differences across gender or residency. The prevalence of albuminuria was 1–2% in the locations irrespective of CKDu burden. Albuminuric participants reported higher (p < 0.05) urinary KIM-1 levels in comparison to normoalbuminuric participants. Significantly elevated urinary KIM-1 expression in a pediatric population from CKDu affected regions, especially in the presence of albuminuria, may indicate low-grade early renal damage supporting the utility of KIM-1 as a quantifiable biomarker.

Urinary Biomarkers of Renal Injury KIM-1 and NGAL: Reference Intervals for Healthy Pediatric Population in Sri Lanka

Emerging renal biomarkers (e.g., kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL)) are thought to be highly sensitive in diagnosing renal injury. However, global data on reference intervals for emerging biomarkers in younger populations are lacking. Here, we aimed to determine reference intervals for KIM-1 and NGAL across a pediatric population in Sri Lanka; a country significantly impacted by the emergence of chronic kidney disease of unexplained etiology (CKDu). Urine samples were collected from children (10–18 years) with no prior record of renal diseases from the dry climatic zone of Sri Lanka (N = 909). Urinary KIM-1 and NGAL concentrations were determined using the enzyme-linked immunosorbent assay (ELISA) and adjusted to urinary creatinine. Biomarker levels were stratified by age and gender, and reference intervals derived with quantile regression (2.5th, 50th, and 97.5th quantiles) were expressed at 95% CI. The range of median reference intervals for urinary KIM-1 and NGAL in children were 0.081–0.426 ng/mg Cr, 2.966–4.850 ng/mg Cr for males, and 0.0780–0.5076 ng/mg Cr, 2.0850–3.4960 ng/mg Cr for females, respectively. Renal biomarkers showed weak correlations with age, gender, ACR, and BMI. Our findings provide reference intervals to facilitate screening to detect early renal damage, especially in rural communities that are impacted by CKDu.

Biomarkers as predictors of renal damage in neonates undergoing cardiac surgery

BACKGROUND

Acute Kidney Injury is a complication in children with heart disease undergoing cardiac surgery with cardiopulmonary bypass. The aim of this study is to describe the behavior of KIM-1 (Kidney Injury Molecule) and NGAL (Neutrophil Gelatinase Associated Lipocalin) as early predictors of renal damage, comparing them with serum creatinine and creatinine clearance, in neonates undergoing cardiac surgery.

METHODS

Twenty-one (21) neonates, under 4 kg, with complex congenital heart diseases, RACHS-1 > 3, without preoperative renal failure, were studied. Serum creatinine and creatinine clearance were measured preoperatively and at 24, 48, 72, 96 hours postoperatively. Urinary samples of KIM-1(pg/ml) and NGAL (ng/ml) were collected after induction of anesthesia at 24 and 48 hours post-operatively.

RESULTS

nRIFLE criteria were used to divide cohorts in "NO AKI" (12 patients) and "AKI" (nine patients). In the AKI group, serum creatinine increased significantly and creatinine clearance decreased significantly at 24, 48, and 72 hours compared with their respective baseline values. There was no difference in KIM-1 and NGAL values between patients who developed AKI and those who did not at any measured time.

CONCLUSIONS

The deterioration of renal function continues to be one of the most frequent complications in this population. In our study, biomarkers did not show any correlation with the appearance of AKI. It remains to be seen whether this behavior of the biomarkers is linked with the non-consistent release of these types of molecules in immature kidneys. It is likely that a larger panel of biomarkers together with other glomerular filtration rate assessment methods will provide more information about AKI diagnosis.

Prognostic value of serum and urine kidney injury molecule-1 in infants with urinary tract infection

Introduction

Kidney injury molecule-1 (KIM-1) is an important diagnostic and prognostic marker in acute kidney injury and chronic kidney disease of various aetiologies. The aim of the study was to evaluate the usefulness of serum KIM-1 (sKIM-1) and urine KIM-1 (uKIM-1) for predicting febrile and non-febrile urinary tract infection (UTI) in infants.

Material and methods

A prospective study included 101 children divided into three groups: febrile UTI 49 children, non-febrile UTI 22 children, and healthy controls 30 children. The following laboratory tests were performed: sKIM-1, uKIM-1, white blood count (WBC), C-reactive protein (CRP), and procalcitonin (PCT).

Results

Median levels of sKIM-1 were significantly higher in the febrile and non-febrile UTI group compared to the healthy controls (both p < 0.05). Mean levels of uKIM-1 were significantly lower in the febrile UTI group compared to the non-febrile UTI group and healthy controls (p < 0.001 and p < 0.0001, respectively). Univariate logistic regression analysis has demonstrated a positive association of sKIM-1 with febrile and non-febrile UTI (both p < 0.05), and negative association uKIM-1 with febrile UTI (p < 0.0001). Receiver operating curve (ROC) analysis showed good diagnostic profiles of uKIM-1 with a best cut-off value of 2.4 ng/ml and sKIM-1 with a best cut-off value of 3.88 ng/ml for predicting febrile UTI (area under the curve [AUC] 0.82 and 0.67, sensitivity 73% and 63%, specificity 86% and 80%, respectively).

Conclusions

sKIM-1 can be useful for predicting febrile UTI. We do not recommended use of uKIM-1 as a marker of febrile UTI because of its negative association with febrile UTI. Both markers are not useful for predicting non-febrile UTI.

Tubular and Glomerular Biomarkers of Acute Kidney Injury in Newborns

BACKGROUND

Acute Kidney Injury (AKI) is a sudden decrease in kidney function. In the early period, the highest percentage of AKI occurs among newborns hospitalized in the neonatal intensive care units, especially premature neonates. The prognosis of AKI depends on the type and severity of the cause of an injury, the accuracy and the time of diagnosis and treatment. The concentration of serum creatinine is still the main diagnostic test, although it changes in the course of AKI later than glomerular filtration rate GFR. In addition, the reliability of the determination of creatinine level is limited because it depends on many factors. New studies have presented other, more useful laboratory markers of renal function that can be measured in serum and/or in urine.

OBJECTIVE

The aim of the work was to present the latest data about tubular and glomerular biomarkers of acute kidney injury in newborns.

METHODS

We undertook a structured search of bibliographic databases for peer-reviewed research literature by using focused review topics. According to the conceptual framework, the main idea of research literature has been summarized and presented in this study.

RESULTS

The concentrations of some novel biomarkers are higher in serum and/or urine of term and preterm newborns with AKI, especially in the course of perinatal asphyxia.

CONCLUSION

In this systematic review of the literature, we have highlighted the usefulness of biomarkers in predicting tubular and/or glomerular injury in newborns. However, novel biomarkers need to prove their clinical applicability, accuracy, and cost-effectiveness prior to their implementation in clinical practice.

Baseline urinary KIM-1 concentration in detecting acute kidney injury should be interpreted with patient pre-existing nephropathy

Objectives

To determine whether pre-existing nephropathy impacts urinary KIM-1 levels, urinary KIM-1 were measured in patients with normal kidney filtration function but either with or without proteinuria. The reference intervals of urinary KIM-1 in adults with normal kidney filtration function but without urine proteinuria were established.

Design and methods

188 urine samples were obtained from adults with normal kidney filtration. 83 of the 188 showed negative urine protein, erythrocytes and leucocytes were used as normal controls. The remaining 105 samples showed at least one abnormal result suggesting possible pre-existing nephropathy. Urinary KIM-1 concentrations were measured using an enzyme-linked immunosorbent assay. Urinary KIM-1 was normalized with urine creatinine concentration. The reference interval for urinary KIM-1 was determined by non-parametric methodology on 147 individuals.

Results

The results showed significantly increased urinary KIM-1 concentration in protein positive (protein +, erythrocyte +/−, leucocyte+/-) samples compared to controls (protein-, erythrocyte -, leucocyte -). Urinary KIM-1 concentrations were significantly higher when proteinuria was at trace concentration (0.25 g/L) and correlated with the severity of proteinuria. The creatinine normalized urinary KIM-1 was significantly higher when urine protein was 1 + to 3+ (0.75–5 g/L). The reference interval for urinary KIM-1 was 0.00 (90%CI: 0-0) to 4.19 (90%CI: 3.11–5.62) μg/L, and for creatinine normalized urinary KIM-1 0.00 (90%CI: 0-0) to 0.58 (90%CI: 0.44–0.74) μg/mmol.

Conclusions

Baseline urinary KIM-1 concentrations were increased when there was detectable urine protein and correlated with its severity. The urinary KIM-1 concentrations should be interpreted with consideration of urine protein levels in individual patients.

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The correlation of urinary KIM-1 with pre-existing evidence of nephropathy such as proteinuria, hematuria and pyuria was investigated.

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Urinary KIM-1 was normalized to urine creatinine concentration.

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Urinary KIM-1 reference intervals for healthy adults with normal kidney filtration and without proteinuria were established.

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Age and sex effects on the urinary KIM-1 concentration were investigated.

Urinary kidney injury molecule-1 in renal disease

Kidney injury molecule-1 (KIM-1), a type l transmembrane glycoprotein, is recognized as a potential biomarker for detection of tubular injury in the main renal diseases. Urinary KIM-1 increases rapidly upon the tubular injury, and its levels are associated with the degree of tubular injury, interstitial fibrosis, and inflammation in the injured kidney. Currently, the investigation of kidney diseases is usually performed through the assessment of serum creatinine and urinary albumin. However, these biomarkers are limited for the early detection of changes in renal function. Besides, the tubular injury appears to precede glomerular damage in the pathophysiology of renal diseases. For these reasons, the search for sensitive, specific and non-invasive biomarkers is of interest. Therefore, the purpose of this article is to review the physiological mechanisms of KIM-1, as well to present clinical evidence about the association between elevated urinary KIM-1 levels and the main renal diseases such as chronic kidney disease, diabetic kidney disease, acute kidney injury, and IgA nephropathy.