Autosomal polycystic kidney disease (ADPKD) is the most common genetic form of kidney failure, reflecting unmet needs in management. Prescription of the only approved treatment (tolvaptan) is limited to persons with rapidly progressing ADPKD. Rapid progression may be diagnosed by assessing glomerular filtration rate (GFR) decline, usually estimated (eGFR) from equations based on serum creatinine (eGFRcr) or cystatin-C (eGFRcys). We have assessed the concordance between eGFR decline and identification of rapid progression (rapid eGFR loss), and measured GFR (mGFR) declines (rapid mGFR loss) using iohexol clearance in 140 adults with ADPKD with ≥3 mGFR and eGFRcr assessments, of which 97 also had eGFRcys assessments. The agreement between mGFR and eGFR decline was poor: mean concordance correlation coefficients (CCCs) between the method declines were low (0.661, range 0.628 to 0.713), and Bland and Altman limits of agreement between eGFR and mGFR declines were wide. CCC was lower for eGFRcys. From a practical point of view, creatinine-based formulas failed to detect rapid mGFR loss (-3 mL/min/y or faster) in around 37% of the cases. Moreover, formulas falsely indicated around 40% of the cases with moderate or stable decline as rapid progressors. The reliability of formulas in detecting real mGFR decline was lower in the non-rapid-progressors group with respect to that in rapid-progressor patients. The performance of eGFRcys and eGFRcr-cys equations was even worse. In conclusion, eGFR decline may misrepresent mGFR decline in ADPKD in a significant percentage of patients, potentially misclassifying them as progressors or non-progressors and impacting decisions of initiation of tolvaptan therapy.

Infective endocarditis (IE) is a highly fatal disease in cases of delayed diagnosis and treatment, although its incidence is low. However, there have been few single-center studies in which the risk of in-hospital death from IE was stratified according to laboratory findings on admission and the organism responsible for IE. In this study, a total of 162 patients who were admitted to our hospital during the period from 2009 to 2021, who were suspected of having IE according to the modified Duke classification, and for whom IE was confirmed by transesophageal echocardiography were retrospectively analyzed. Patients were observed for a mean-period of 43.7 days with the primary endpoint being in-hospital death. The in-hospital death group had a lower level of hemoglobin (Hb), higher white blood cell (WBC) count, lower level of estimated glomerular filtration rate (eGFR), and higher frequency of Staphylococcus being the causative agent than those in the non-in-hospital death group. In overall multivariate analysis, Hb, WBC count, eGFR, and Staphylococcus as the causative agent were identified to be significant prognostic determinants. IE patients with Hb < 10.6 g/dL, WBC count > 1.4 × 104/μL, eGFR < 28.1 mL/minute/1.7 m2, and Staphylococcus as the causative agent had significantly and synergistically increased in-hospital death rates compared to those in other IE patients. Low level of Hb, high WBC count, low eGFR, and Staphylococcus as the causative agent of IE were independent predictors of in-hospital mortality, suggesting that these 4 parameters may be combined to additively stratify the risk of in-hospital mortality.

BACKGROUND: At present, estimated glomerular filtration rate (eGFR) remains the most frequently utilized parameter in the evaluation of kidney injury severity. Numerous equations have been formulated based on serum creatinine (Scr) or serum cystatin C (Cysc) levels. However, there is a lack of consensus regarding the efficacy of these equations in assessing eGFR, particularly for elderly individuals in China. This study aimed to evaluate the applicability of the MDRD, MDRDc, CKD-EPI series, BIS1, and FAS equations within the Chinese elderly population.
METHODS: A cohort of 298 elderly patients with measured GFR (mGFR) was enrolled. The patients were categorized into three subgroups based on their mGFR levels. The eGFR performance was examined, taking into account bias, interquartile range (IQR), accuracy P30, and root-mean-square error (RMSE). Bland-Altman plots were employed to verify the validity of eGFR.
RESULTS: The participants had a median age of 71 years, with 167 (56.0%) being male. Overall, no significant differences in bias were observed among the seven equations (P > 0.05). In terms of IQR, P30, and RMSE, the BIS1 equation demonstrated superior accuracy (14.61, 72.1%, and 13.53, respectively). When mGFR < 30 ml/min/1.73 m2, all equations underestimated the true GFR, with the highest accuracy reaching only 59%. Bland-Altman plots indicated that the BIS1 equation exhibited the highest accuracy, featuring a 95% confidence interval (CI) width of 52.37.
CONCLUSIONS: This study suggested that the BIS1 equation stands out as the most applicable for estimating GFR in Chinese elderly patients with normal renal function or only moderate decline. 2020NL-085-03, 2020.08.10, retrospectively registered.

Background. Estimated GFR (eGFR) is calculated using serum creatinine (SCr) based equations which have their own limitations. Novel biomarkers like beta trace protein (BTP) are studied for eGFR estimation. The aim of this study is to determine the serum levels of BTP in healthy controls and chronic kidney disease (CKD) cases and to find out the correlation of BTP levels with that of SCr and SCr-based eGFR formulas. Methods. The control group comprised of 20 healthy adults. The cases comprised of 20 patients each in CKD stages 3, 4, and 5, categorized based on eGFR calculated using MDRD formula. Baseline characteristics of the study population were recorded. BTP was measured by ELISA (Enzyme Linked Immunosorbent Assay) method and SCr by modified Jaffe\'s method. The statistical analyses were performed with the SPSS for Windows, version 16.0. Results. The median value of blood urea nitrogen (BUN) in the cases was 26.50 mg/dL (IQR 19.25-37) and for control it was 9.5 mg/dL (IQR 8-12). The median value of SCr in the cases was 2.75 mg/dL (IQR 1.725-4.45) and in the controls, it was 0.7mg/dL (IQR 0.6 -0.8). The median value of BTP in cases was 6389.25 ng/ml (IQR 5610.875-10713.75) and in controls, it was 1089.5 ng/ml (IQR 900.5-1309.75). Conclusion. Serum BTP levels correlated with SCr levels and renal function. We could establish the relationship between the two biomarkers, SCr and BTP, and derive a regression equation.

Cadmium (Cd) is a pervasive, toxic environmental pollutant that preferentially accumulates in the tubular epithelium of the kidney. Current evidence suggests that the cumulative burden of Cd here leads to the progressive loss of the glomerular filtration rate (GFR). In this study, we have quantified changes in estimated GFR (eGFR) and albumin excretion (Ealb) according to the levels of blood Cd ([Cd]b) and excretion of Cd (ECd) after adjustment for confounders. ECd and Ealb were normalized to creatinine clearance (Ccr) as ECd/Ccr and Ealb/Ccr. Among 482 residents of Cd-polluted and non-polluted regions of Thailand, 8.1% had low eGFR and 16.9% had albuminuria (Ealb/Ccr) × 100 ≥ 20 mg/L filtrate. In the low Cd burden group, (ECd/Ccr) × 100 < 1.44 µg/L filtrate, eGFR did not correlate with ECd/Ccr (β = 0.007) while an inverse association with ECd/Ccr was found in the medium (β = -0.230) and high burden groups (β = -0.349). Prevalence odds ratios (POR) for low eGFR were increased in the medium (POR 8.26) and high Cd burden groups (POR 3.64). Also, eGFR explained a significant proportion of Ealb/Ccr variation among those with middle (η2 0.093) and high [Cd]b tertiles (η2 0.132) but did not with low tertiles (η2 0.001). With an adjustment of eGFR, age and BMI, the POR values for albuminuria were increased in the middle (POR 2.36) and high [Cd]b tertiles (POR 2.74) and those with diabetes (POR 6.02) and hypertension (2.05). These data indicate that (ECd/Ccr) × 100 of 1.44 µg/L filtrate (0.01-0.02 µg/g creatinine) may serve as a Cd threshold level based on which protective exposure guidelines should be formulated.

UNASSIGNED: Use of cystatin C in addition to creatinine to estimate glomerular filtration rate (estimated glomerular filtration rate based on cystatin C [eGFRcys] and estimated glomerular filtration rate based on creatinine [eGFRcr], respectively) is increasing. When eGFRcr and eGFRcys are discordant, it is not known which is more accurate, leading to uncertainty in clinical decision making.
UNASSIGNED: Cross-sectional analysis.
UNASSIGNED: Four thousand fifty participants with measured glomerular filtration rate (mGFR) from 12 studies in North America and Europe.
UNASSIGNED: Serum creatinine and serum cystatin C.
UNASSIGNED: Performance of creatinine-based and cystatin C-based glomerular filtration rate estimating equations compared to mGFR.
UNASSIGNED: We evaluated the accuracy of eGFRcr, eGFRcys, and the combination (eGFRcr-cys) compared to mGFR according to the magnitude of the difference between eGFRcr and eGFRcys (eGFRdiff). We used CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equations to estimate glomerular filtration rate. eGFRdiff was defined as eGFRcys minus eGFRcr and categorized as less than -15, -15 to <15, and ≥15 mL/min/1.73 m2 (negative, concordant, and positive groups, respectively). We compared bias (median of mGFR minus eGFR) and the percentage of eGFR within 30% of mGFR.
UNASSIGNED: Thirty percent of participants had discordant eGFRdiff (21.0% and 9.6% negative and positive eGFRdiffs, respectively). In the concordant eGFRdiff group, all equations displayed similar accuracy. In the negative eGFRdiff groups, eGFRcr had a large overestimation of mGFR (-13.4 [-14.5 to -12.2] mL/min/1.73 m2) and eGFRcys had a large underestimation (9.9 [9.1-11.2] mL/min/1.73m2), with opposite results in the positive eGFRdiff group. In both negative and positive eGFRdiff groups, eGFRcr-cys was more accurate than either eGFRcr or eGFRcys. These results were largely consistent across age, sex, race, and body mass index.
UNASSIGNED: Few participants with major comorbid conditions.
UNASSIGNED: Discordant eGFRcr and eGFRcys are common. eGFR using the combination of creatinine and cystatin C provides the most accurate estimates among persons with discordant eGFRcr or eGFRcys.

Glomerular filtration rate (GFR) is thought to be the best overall indicator of kidney health. On an individual patient basis, a working knowledge of GFR is important to understand the future risk for chronic kidney disease (CKD) progression, enhanced risk for cardiovascular disease and death, and for optimal medical management including the dosing of certain drugs. Although GFR can be directly measured using exogenous compounds that are eliminated by the kidney, these methods are not scalable for repeated and routine use in clinical care. Thus, in most circumstances GFR is estimated, termed estimated GFR (eGFR), using serum biomarkers that are eliminated by the kidney. Of these, serum creatinine, and to a lesser extent cystatin C, are most widely employed. However, the resulting number is simply a population average for an individual of that age and sex with a given serum creatinine and/or cystatin C, while the range of potential GFR values is actually quite large. Thus, it is important to consider characteristics of a given patient that might make this estimate better or worse in a particular case. In some circumstances, cystatin C or creatinine might be the better choice. Ultimately it is difficult, if not impossible, to have an eGFR equation that performs equally well in all populations. Thus, in certain cases it might be appropriate to directly measure GFR for high consequence medical decision-making, such as approval for kidney donation or prior to certain chemotherapeutic regimens. In all cases, the eGFR thresholds of CKD stage should not be viewed as absolute numbers. Thus, clinical care should not be determined solely by CKD stage as determined by eGFR alone, but rather by the combination of an individual patient\'s likely kidney function together with their current clinical situation.

Chronic kidney disease (CKD) is a major health problem, and the risk of CKD and hypertension in children born low birth weight (LBW) is under-recognized. We hypothesized that children born with LBW would have a higher prevalence of reduced kidney function and hypertension.
Using the National Health and Nutrition Examination Survey (NHANES), we conducted a cross-sectional study to evaluate whether LBW (< 2500 g), very low birth weight (VLBW < 1500 g), and large birth weight (BW) (> 4000 g) were associated with kidney disease using 4 different estimating equations. We used the Counahan-Barratt, updated Schwartz, CKiD-U25, and full age spectrum creatinine-based GFR estimating equations to evaluate associations between a history of LBW/VLBW/large BW and reduced kidney function (eGFR < 90 mL/min/1.73 m2) in children. We also assessed blood pressure (BP) using the old and new pediatric hypertension guidelines.
Our analysis included 6336 children (age 12-15 years) in NHANES representing over 13 million US individuals. Using the updated Schwartz, the prevalence of reduced kidney function was 30.1% (25.2-35.6) for children born with LBW compared to 22.4% (20.5-24.3) in children with normal BW. Equations yielded different estimates of prevalence of reduced kidney function in LBW from 21.5% for Counahan-Barratt to 35.4% for CKiD-U25. Compared to those with normal BW, participants with LBW and VLBW had a 7.2 and 10.3% higher prevalence of elevated BP and a 2.4 and 14.6% higher prevalence of hypertension, respectively.
Children born with LBW are at higher risk of reduced kidney function and hypertension than previously described. A higher resolution version of the Graphical abstract is available as Supplementary information.

A reliable assessment of renal function is of paramount importance in several clinical assets in order to tailor a personalized medical approach. CKD classification system, created in 2002 by the National Kidney Foundation-sponsored Kidney Disease Outcomes Quality Initiative and then implemented in the following years by the K-DIGO guidelines, offered clinicians a new strategy to better identify nephrological patients at low or high risk to develop renal insufficiency, in order to avoid the progression to end-stage renal disease. However, the criteria used to create this classification did not consider some important aspects related to renal histology and glomerular filtration rate measurement, resulting in a possible over- or underestimation of the real established renal damage. In this mini-review, we will summarize the most relevant shortcomings in the CKD classifications, which can create misleading diagnosis in daily clinical practice.

UNASSIGNED: Recent studies evaluated and proposed new race-neutral, creatinine-based glomerular filtration rate (GFR) estimation equations. The performance of these equations in diverse potential living kidney donors requires study.
UNASSIGNED: Cross-sectional study.
UNASSIGNED: 637 potential living kidney donors from one tertiary hospital with serum creatinine concentration measurement and GFR measurement by iohexol plasma clearance between October 2016 and December 2020.
UNASSIGNED: Creatinine-based estimation of GFR by Chronic Kidney Disease Epidemiology Collaboration (2009, CKDEPI09; 2021, CKDEPI21) and Modification of Diet in Renal Disease equations with and without inclusion of race coefficient, where applicable.
UNASSIGNED: Equation bias, precision, accuracy, and accurate classification of GFR as equal to and above or below 80 mL/min/1.73 m2.
UNASSIGNED: GFR estimation equation performance compared to measured GFR (mGFR) by iohexol clearance.
UNASSIGNED: The median bias of the CKDEPI21 equation underestimated mGFR by 2.8 mL/min/1.73 m2. The bias in the Black subgroup underestimated mGFR by 9.0 mL/min/1.73 m2. Compared to CKDEPI09 with and without race adjustment, the accuracy of CKDEPI21 increased across all subgroups. On average, 3.9% of individuals were misclassified by CKDEPI21 as having a GFR greater than, and 8.9% misclassified less than, 80 mL/min/1.73 m2, compared to 3.1% and 13.2% for CKDEPI09 with race adjustment, respectively. Total misclassification (either above or below 80 mL/min/1.73 m2) was 16.3% for CKDEPI21 and 16.0% for CKDEPI09 (with race adjustment).
UNASSIGNED: Limited sample of individuals identifying as Black. Lack of cystatin C data.
UNASSIGNED: In our potential living donor sample, GFR estimation by creatinine-based CKDEPI21 is less biased and more accurate than previous creatinine-based estimated GFR equations. When evaluated by race, this summative improvement remains in individuals identifying as Asian, Hispanic, or White. More external validation is needed to assess whether the new equation is an improvement over the previous CKDEPI equation with a race coefficient.