Prognostic value of urinary calprotectin, NGAL and KIM-1 in chronic kidney disease

$\textbf {Background/Aims:}$ Urinary biomarkers like neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) do not only allow an early diagnosis of acute kidney injury, but also provide prognostic information in this setting. The present prospective study investigates, whether the urinary biomarkers NGAL, KIM-1 and calprotectin have prognostic information in chronic kidney disease (CKD) as well. $\textbf {Methods:}$ Urinary calprotectin, NGAL and KIM-1 concentrations were assessed in a study population of 143 patients with stable CKD comprising diabetic and hypertensive nephropathy, glomerulonephritis/vasculitis, and autosomal dominant polycystic kidney disease. An eGFR fluctuation > 5ml/min/$1.73m^{2}$ in the past 12 months was defined as an exclusion criterion in order to exclude cases with acute on chronic kidney injury. Renal function was monitored for a median follow-up of 37 months. $\textbf {Results:}$ In the overall study population, all the three biomarkers failed to predict DeGFR and DACR from baseline to follow-up in linear regression analysis adjusted for age, gender, and baseline $\Delta$eGFR. Contrarily, baseline ACR was significantly associated with $\Delta$eGFR (p< 0.001). In the subgroup of patients with vasculitis and glomerulonephritis, all the three biomarkers were significantly associated with $\Delta$eGFR, with calprotectin having the highest regression coefficient. $\textbf{Conclusion:}$ In contrast to the traditional biomarker "albuminuria", neither the inflammatory biomarker calprotectin, nor the tubular biomarkers NGAL and KIM-1, provide robust prognostic information on the loss or renal function in a heterogeneous CKD population. All of them, however, are candidate prognostic biomarkers in primarily inflammatory renal diseases

Impact of weather changes on hospital admissions for hypertension

Blood pressure (BP) shows a seasonal variation with higher levels at lower temperatures. Many hypertensives, however, report on BP disturbances rather in association with acutely changing weather conditions than with absolute temperatures. To date, the impact of changing meteorological parameters on hypertensive episodes remains elusive. We performed a retrospective time series regression analysis on 203,703 patients in three hospitals in Germany between 2010 and 2018, of whom 7362 patients were admitted for hypertensive disease. Numbers of daily admissions for hypertension were associated with metereological data obtained from three nearby weather stations. Data comprised temperature (mean, maximal, minimal and range within 24 h), athmospheric pressure, and precipitation. Changes of these parameters were calculated over a two and three day period. There was an inverse correlation between maximal daily temperature and the number of admissions for hypertensive disease, which remained significant both after adjustment for seasonality and week day in a spline model and in a constrained distributed lag model. A decrease of maximal temperature by 5 °C was associated with a 3% increase of risk for admission for hypertension and vice versa. There were no significant effects of precipitation and athmospheric pressure on the number of admissions. With regard to all observed metereological parameters, neither the change within two, nor within three days was consistently associated with the number of daily admissions. High temperatures are associated with lower numbers of hypertensive episodes requiring hospital admission. In contrast to the subjective perception of many hypertensive patients, however, acutely changing weather conditions are not associated with a higher risk of hypertensive emergency

Effects of treatment of asymptomatic hyperuricemia on graft survival and mortality in kidney transplant recipients

$\textbf{Background:}$ Hyperuricemia is very common after renal transplantation. It is associated with an increased risk of cardiovascular events and graft loss. To date, however, treatment is only recommended in symptomatic disease. $\textbf{Material/Methods:}$ We included 503 adult patients who underwent kidney transplantation at the Charité-Universitätsmedizin Berlin in this retrospective study. Patients were followed up for up to 120 months. All-cause mortality, graft survival, changes in level of serum uric acid (SUA), and estimated glomerular filtration rate (eGFR) were analyzed. $\textbf{Results:}$ At 12 months post-transplantation, 225 patients had a serum uric acid (SUA) level >7 mg/dl: 52 patients were treated with allopurinol, 37 with benzbromarone, and 136 patients received no medication for hyperuricemia (control). At 12 months, eGFR did not differ between groups (p=0.15) but treated patients had higher SUA levels (p<0.001) compared to the control group. SUA-lowering treatment was associated with a lower risk of allcause mortality (p=0.013) and graft loss (p=0.014) compared to controls. At 120 months, patients in the treatment group had lower SUA levels (p=0.001) and higher eGFR (p<0.001) compared to the control group. $\textbf{Conclusions:}$ Treatment of asymptomatic hyperuricemia was associated with a substantial benefit in patient and graft survival

Urinary calprotectin and posttransplant renal allograft injury

$\textit {Objective:}$ Current methods do not predict the acute renal allograft injury immediately after kidney transplantation. We evaluated the diagnostic performance of urinary calprotectin for predicting immediate posttransplant allograft injury. $\textit {Methods:}$ In a multicenter, prospective-cohort study of 144 incipient renal transplant recipients, we postoperatively measured urinary calprotectin using an enzyme-linked immunosorbent assay and estimated glomerular filtration rate (eGFR) after 4 weeks, 6 months, and 12 months. $\textit {Results:}$ We observed a significant inverse association of urinary calprotectin concentrations and eGFR 4 weeks after transplantation (Spearman r = −0.33; P<0.001). Compared to the lowest quartile, patients in the highest quartile of urinary calprotectin had an increased risk for an eGFR less than 30 mL/min/1.73 $m^{2}$ four weeks after transplantation (relative risk, 4.3; P<0.001; sensitivity, 0.92; 95% CI, 0.77 to 0.98; specificity, 0.48; 95% CI, 0.31 to 0.66). Higher urinary calprotectin concentrations predicted impaired kidney function 4 weeks after transplantation, as well as 6 months and 12 months after transplantation. When data were analyzed using the urinary calprotectin/creatinine-ratio similar results were obtained. Urinary calprotectin was superior to current use of absolute change of plasma creatinine to predict allograft function 12 months after transplantation. Urinary calprotectin predicted an increased risk both in transplants from living and deceased donors. Multivariate linear regression showed that higher urinary calprotectin concentrations and older donor age predicted lower eGFR four weeks, 6 months, and 12 months after transplantation. $\textit {Conclusions:}$ Urinary calprotectin is an early, noninvasive predictor of immediate renal allograft injury after kidney transplantation

Dickkopf-3 in the prediction of contrast media induced acute kidney injury

$\bf Background$ Dickkopf-3 (DKK3) has recently been discovered as a urinary biomarker for the prediction of acute kidney injury (AKI) after cardiac surgery. This finding needs to be confirmed for AKI in other clinical settings. The present study investigates whether DKK3 can predict contrast-induced AKI (CI-AKI). $\bf Methods$ We performed a prospective study in 490 patients undergoing coronary angiography. Primary endpoint was an increase in serum creatinine concentration $\geq$ 0.3 mg/dl within 72 h after the procedure. DKK3 was assessed < 24 h before coronary angiography. Predictive accuracy was assessed by receiver operating characteristic (ROC) curves. $\bf Results$ CI-AKI was observed in 30 (6.1%) patients, of whom 27 corresponded to stage I and 3 to stage II according to the Acute Kidney Injury Network (AKIN) criteria. Subjects who developed CI-AKI had a 3.8-fold higher urinary DKK3/creatinine ratio than those without CI-AKI (7.5 pg/mg [interquartile range [IQR] 1.2–1392.0] vs. 2.0 pg/mg [IQR 0.9–174.0]; $\it p$ = 0.047). ROC analysis revealed an area under the curve (AUC) of 0.61. Among subjects without clinically overt chronic kidney disease (estimated glomerular filtration rate [eGFR] > 60 ml/min, urinary albumin creatinine ratio < 30 mg/g), the DKK3/creatinine ratio was 5.4-fold higher in those with subsequent CI-AKI (7.5 pg/mg [IQR 0.9–590.1] vs. 1.38 pg/mg [IQR 0.8–51.0]; $\it p$ = 0.007; AUC 0.62). Coronary angiography was associated with a 43 times increase in the urinary DKK3/creatinine ratio. $\bf Conclusions$ Urinary DKK3 is an independent predictor of CI-AKI even in the absence of overt chronic kidney disease (CKD). The study thereby expands the findings on DKK3 in the prediction of postoperative loss of kidney function to other entities of AKI

Detection of acute tubular necrosis using blood oxygenation level-dependent (BOLD) MRI

$\it Background/Aims:$ To date, there is no imaging technique to assess tubular function in vivo. Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) measures tissue oxygenation based on the transverse relaxation rate (R2*). The present study investigates whether BOLD MRI can assess tubular function using a tubule-specific pharmacological maneuver. $\it Methods:$ Cross sectional study with 28 participants including 9 subjects with ATNinduced acute kidney injury (AKI), 9 healthy controls, and 10 subjects with nephron sparing tumor resection (NSS) with clamping of the renal artery serving as a model of ischemia/reperfusion (I/R)-induced subclinical ATN (median clamping time 15 min, no significant decrease of eGFR, p=0.14). BOLD MRI was performed before and 5, 7, and 10 min after intravenous administration of 40 mg furosemide. $\it Results:$ Urinary neutrophil gelatinaseassociated lipocalin was significantly higher in ATN-induced AKI and NSS subjects than in healthy controls (p=0.03 and p=0.01, respectively). Before administration of furosemide, absolute medullary R2*, cortical R2*, and medullary/cortical R2* ratio did not significantly differ between ATN-induced AKI vs. healthy controls and between NSS-I/R vs. contralateral healthy kidneys (p>0.05 each). Furosemide led to a significant decrease in the medullary and cortical R2* of healthy subjects and NSS contralateral kidneys (p0.05 each). $\it Conclusion:$ BOLD-MRI is able to detect even mild tubular injury but necessitates a tubulespecific pharmacological maneuver, e.g. blocking the Na$^{+}$-K$^{+}$-2Cl- transporter by furosemide

Biopsy findings after detection of de novo donor-specific antibodies in renal transplant recipients

$\bf Background$ De novo donor-specific antibodies (DSA) are associated with an increased risk of antibody-mediated rejection and a substantial reduction of allograft survival. We hypothesized that detection of DSA should prompt a biopsy even in the absence of proteinuria and loss of estimated glomerular filtration rate (eGFR). However, data on a population without proteinuria or loss of kidney function is scant, and this is the main novelty of our study design. $\bf Methods$ Single center retrospective analysis on biopsy findings after detection of de novo DSA. One-hundred-thirty-two kidney and pancreas-kidney transplant recipients were included. Eighty-four of these patients (63.6%) underwent allograft biopsy. At the time of biopsy n = 50 (59.5%) had a protein/creatinine ratio (PCR) > 300 mg/g creatinine and/or a loss of eGFR $\geq$ 10 ml/min in the previous 12 months, whereas 40.5% did not. Diagnosis of rejection was performed according to Banff criteria. $\bf Results$ Seventy-seven (91.7%) of the biopsies had signs of rejection (47.6% antibody mediated rejection (ABMR), 13.1% cellular, 20.2% combined, 10.7% borderline). Among subjects without proteinuria or loss of eGFR $\geq$ 10 ml/min/a (n = 34), 29 patients (85.3%) showed signs of rejection (44.1% antibody mediated (ABMR), 14.7% cellular, 11.8% combined, 14.7% borderline). $\bf Conclusion$ The majority of subjects with de novo DSA have histological signs of rejection, even in the absence of proteinuria and deterioration of graft function. Thus, it appears reasonable to routinely perform an allograft biopsy after the detection of de novo DSA

The impact of acute diarrhea on the coagulation status of patients with vitamin K antagonists

Acute diarrhea is associated with a reduced absorption of both vitamin K antagonists (VKA) and vitamin K itself. To date, the net effect on the coagulation status of subjects with VKA remains elusive. We performed a systematic retrospective single-center analysis using an electronic data extraction approach to identify subjects with plasmatic anticoagulation (either VKA or direct oral anticoagulant (DOAC)) and diarrhea in a German University Hospital over a period of eight years. Acute diarrhea and complete documentation of coagulation status on admission were defined as inclusion criteria, anticoagulation other than VKA/DOAC and obvious inadherence as exclusion criteria. Subjects with VKA/DOAC admitted for hypertension served as control group. Data extraction yielded 356 subjects with gastrointestinal diagnoses and 198 hypertensive subjects, 55 and 83 of whom fulfilled all in- and exclusion criteria. INR values of subjects with VKA were significantly higher in subjects with diarrhea than in hypertensive controls (4.3 $\pm$ 3.7 vs. 2.3 $\pm$ 0.7, $\it p$  0.05 each). Acute diarrhea is associated with a highly increased risk for overanticoagulation in patients with VKA. Thus, gastroenteritis necessitates a close monitoring of INR in order to identify subjects needing a temporary pause of VKA therapy

Detection of SARS-CoV-2 pneumonia

$\bf Background:$ Developing therapeutic strategies for a SARS-CoV-2 infection is challenging, but first the correct diagnosis has to be made. Unspecific upper and lower respiratory tract symptoms can be misleading; hence, a nasopharyngeal swab test with a real-time reverse-transcription-polymerase chain reaction is of great importance. However, early viral clearing jeopardizes a sound diagnosis of COVID-19. $\textbf {Case presentation:}$ We report on two Caucasian patients who had negative pharyngeal swab tests at the onset of SARS-CoV-2 pneumonia. In one patient, the virus was not even detectable in bronchoalveolar lavage despite typical radiomorphologic changes. $\bf Conclusions:$ Negative PCR findings in both the pharynx and bronchoalveolar lavage do not exclude COVID-19 pneumonia. Computed tomography is a crucial diagnostic prerequisite in this context

Biomarkers in the prediction of contrast media induced nephropathy

$\bf Background$ Subjects with chronic kidney disease are at increased risk for contrast-induced acute kidney injury (CI-AKI). Risk stratification is traditionally based on glomerular filtration rate (GFR) and proteinuria. The present trial examines, whether tubular and inflammatory biomarkers are able to identify subjects at increased risk as well. $\bf Methods$ We performed a prospective study in 490 patients undergoing coronary angiography. An increase of serum creatinine concentration $\geq$ 0.3 mg/dl from baseline to day 2–3 was defined as primary endpoint (CI-AKI). Urinary neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and calprotectin were assessed < 24h before coronary angiography. Prognostic accuracy was assessed by receiver operating characteristics (ROC) calculations. $\bf Results$ 30 (6.1%) patients suffered from CI-AKI (27 AKIN stage I, 3 AKIN stage II, 0 AKIN stage III). Those subjects who developed CI-AKI had 3.1 fold higher baseline urinary NGAL/creatinine ratios than those without CI-AKI (60.8 [IQR 18.7–93.1] $\mu$g/mg vs. 19.9 [IQR 12.3–38.9] $\mu$g/mg, p = 0.001). In those subjects without clinically overt CKD (eGFR > 60 ml/min, urinary albumin creatinine ratio 0.05 each). ROC analyses revealed an area under the curve (AUC) of 0.68 (95% CI 0.60–0.81) for NGAL/creatinine. An NGAL/creatinine ratio < 56.4 $\mu$g/mg has a negative predictive value of 96.5%. $\bf Conclusions$ The present study is the largest investigation on the use of urinary biomarkers for CI-AKI risk stratification so far. It shows that NGAL provides prognostic information beyond the glomerular biomarkers eGFR and proteinuria