Acute Kidney Injury and Kidney Damage in COVID-19 Patients.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This disease, which is quickly spreading worldwide, has high potential for infection and causes rapid progression of lung lesions, resulting in a high mortality rate. This study aimed to investigate the effects of SARS-CoV-2 infection on renal function in patients with COVID-19. METHODS: From February 21 to April 24, 2020, 66 patients diagnosed with COVID-19 at Chungnam National University Hospital were analyzed; all patients underwent routine urinalysis and were tested for serum creatinine, urine protein to creatinine ratio (PCR), and urine albumin to creatinine ratio (ACR). RESULTS: Acute kidney injury (AKI) occurred in 3 (4.5%) of the 66 patients, and 1 patient with AKI stage 3 underwent hemodialysis. Upon follow-up, all 3 patients recovered normal renal function. Compared with patients with mild COVID-19, AKI (n = 3) occurred in patients with severe COVID-19, of whom both urine PCR and ACR were markedly increased. CONCLUSION: The incidence of AKI was not high in COVID-19 patients. The lower mortality rate in SARS-CoV-2 infection compared with previous Middle East respiratory syndrome and SARS-CoV infections is thought to be associated with a low incidence of dysfunction in organs other than the lungs.

Reversible Acute Blindness in Suspected Metformin-Associated Lactic Acidosis.

BACKGROUND: Metformin is commonly used for the treatment of type 2 diabetes mellitus. Renal insufficiency is one of the contraindications for its use. Inadvertent prescription in patients with renal insufficiency may lead to metformin-associated lactic acidosis (MALA), which is associated with a high risk of mortality. Consequently, the early recognition and management of MALA is essential. CASE REPORT: We present the case of a 68-year-old man who had reversible blindness resulting from severe lactic acidosis. On presentation, he was alert, oriented, and had no complaints except mild abdominal discomfort and blindness. He denied any history of trauma or drug abuse. The results of the laboratory studies showed severe metabolic acidosis with a high anion gap and increased levels of serum creatinine. There were no predisposing ocular or neurologic lesions that could have induced the blindness. Although the blood levels of methanol, ethanol, and metformin were not estimated, correction of acidosis and hemodialysis led to a complete recovery. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Rarely, transient blindness may occur in patients with fatal severe metabolic acidosis. Evaluation for the presence of metabolic acidosis and a detailed medical history are essential in the management of acute blindness in such patients.

Ratio of Extracellular to Intracellular Water Is Associated with Permanent Catheter Patency Survival in Patients Receiving Maintenance Hemodialysis.

Patients undergoing dialysis through a permanent catheter often experience infection or malfunction. However, few studies have clarified the predictors of permanent catheter patency survival in patients undergoing hemodialysis. We assessed the relationship between the parameters of body composition monitoring (BCM), determined before the initiation of dialysis, and the patency survival of the permanent catheters inserted in 179 patients who commenced hemodialysis between 14 January 2020 and 31 August 2021. The relationships between permanent catheter patency at 6 weeks and BCM parameters, laboratory tests, age, sex, comorbidities, and medications at baseline were studied using Kaplan-Meier survival curves. Permanent catheter patency was observed to be superior at high extracellular-to-intracellular (ECW/ICW) ratio (p < 0.005). After adjustment for covariates, the ECW/ICW ratio remained an independent factor associated with permanent catheter patency survival. When patients with non-patent catheters were subdivided into infection and malfunction groups, and the associations of BCM parameters were evaluated in those groups, the ECW/ICW ratio was not significantly associated with permanent catheter patency survival in the infection group (p = 0.327); instead, a significant association was found for the lean tissue index (p < 0.001). In the malfunction group, the ECW/ICW ratio remained significantly associated with permanent catheter patency survival (p < 0.001).

Diagnostic and Prognostic Roles of C-Reactive Protein, Procalcitonin, and Presepsin in Acute Kidney Injury Patients Initiating Continuous Renal Replacement Therapy.

For reducing the high mortality rate of severe acute kidney injury (AKI) patients initiating continuous renal replacement therapy (CRRT), diagnosing sepsis and predicting prognosis are essential. However, with reduced renal function, biomarkers for diagnosing sepsis and predicting prognosis are unclear. This study aimed to assess whether C-reactive protein (CRP), procalcitonin, and presepsin could be used to diagnose sepsis and predict mortality in patients with impaired renal function initiating CRRT. This was a single-center, retrospective study involving 127 patients who initiated CRRT. Patients were divided into sepsis and non-sepsis groups according to the SEPSIS-3 criteria. Of the 127 patients, 90 were in the sepsis group and 37 were in the non-sepsis group. Cox regression analysis was performed to determine the association between the biomarkers (CRP, procalcitonin, and presepsin) and survival. CRP and procalcitonin were superior to presepsin for diagnosing sepsis. Presepsin was closely related to the estimated glomerular filtration rate (eGFR) (r = -0.251, p = 0.004). These biomarkers were also evaluated as prognostic markers. Procalcitonin levels ≥3 ng/mL and CRP levels ≥31 mg/L were associated with higher all-cause mortality using Kaplan-Meier curve analysis. (log-rank test p = 0.017 and p = 0.014, respectively). In addition, procalcitonin levels ≥3 ng/mL and CRP levels ≥31 mg/L were associated with higher mortality in univariate Cox proportional hazards model analysis. In conclusion, a higher lactic acid, sequential organ failure assessment score, eGFR, and a lower albumin level have prognostic value to predict mortality in patients with sepsis initiating CRRT. Moreover, among these biomarkers, procalcitonin and CRP are significant factors for predicting the survival of AKI patients with sepsis-initiating CRRT.

Omega-3 Fatty Acids Attenuate Renal Fibrosis via AMPK-Mediated Autophagy Flux Activation.

The unilateral ureteral obstruction (UUO) injury model is well-known to mimic human chronic kidney disease, promoting the rapid onset and development of kidney injury. ω3-poly unsaturated fatty acids (PUFAs) have been observed to protect against tissue injury in many disease models. In this study, we assessed the efficacy of ω3-PUFAs in attenuating UUO injury and investigated their mechanism of action. The immortalized human proximal tubular cells human kidney-2 (HK2) were incubated for 72 h with docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) in various concentrations, in the presence or absence of transforming growth factor (TGF)-ß. DHA/EPA reduced the epithelial-mesenchymal transition in the TGF-ß-treated HK2 cells by enhancing autophagy flux and adenosine monophosphate-activated protein kinase (AMPK) phosphorylation. C57BL/6 mice were divided into four groups and treated as follows: sham (no treatment, n = 5), sham + ω3-PUFAs (n = 5), UUO (n = 10), and UUO + ω3-PUFAs (n = 10). Their kidneys and blood were harvested on the seventh day following UUO injury. The kidneys of the ω3-PUFAs-treated UUO mice showed less oxidative stress, inflammation, and fibrosis compared to those of the untreated UUO mice. Greater autophagic flux, higher amounts of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II, Beclin-1, and Atg7, lower amounts of p62, and higher levels of cathepsin D and ATP6E were observed in the kidneys of the omega-3-treated UUO mice compared to those of the control UUO mice. In conclusion, ω3-PUFAs enhanced autophagic activation, leading to a renoprotective response against chronic kidney injury.

Artery-to-Fistula Diameter Ratio as a Predictor of Early Re-Occlusion of Immature Right Radio-Cephalic Arteriovenous Fistula after Primary PTA.

Percutaneous transluminal angioplasty (PTA) is widely performed for arteriovenous fistula (AVF) that fails to mature after initial formation. We observed that some immature AVFs re-occlude earlier than others. We sought to investigate the predictors for early post-intervention failure of immature fistulas after primary PTA. We retrospectively reviewed the records and angiographic images of patients who had immature fistulas and thereby received PTA between 2013 and 2019 at our center. We investigated the short-term post-intervention outcomes of the patients within 90 days post-PTA. Patients who had re-occlusion within the period were defined as the early failure group and the rest as the patent group. We investigated factors associated with early failure. There were 80 eligible patients with 22 brachio-cephalic (BC) and 58 radio-cephalic (RC) AVFs. The median age of the patients was 64 years [range, 38-87]. There were 51 (63%) males and 29 (36%) females. Among the 58 RC AVFs, 10 (17%) patients had early failure. Logistic regression analysis showed that a larger artery to fistula (A/F) diameter ratio was the sole independent predictor of early failure after primary PTA (odd ratio 2.29 [1.023-5.147], p value = 0.044). Although further studies on a larger scale are required to confirm the clinical significance, a larger A/F diameter ratio was a potential predictor of early re-occlusion in immature fistulas after primary PTA.

Serum Growth Differentiation Factor-15/Albumin Ratio as a 2-Year Survival Marker of End-Stage Renal Disease Patients Initiating Maintenance Hemodialysis.

It is important to identify risk factors related to mortality in end-stage renal disease (ESRD) patients starting renal replacement therapy. Recently, several studies proposed that growth-differentiation factor-15 (GDF-15) is a possible biomarker for the prognosis of patients on maintenance hemodialysis. Here, we investigated the predictive value of serum GDF-15/Albumin ratio on two-year mortality in ESRD patients initiating maintenance hemodialysis. The study was a single center, retrospective study on ESRD patients starting maintenance hemodialysis with a follow-up of two years. All patients completed laboratory test and bioimpedance spectroscopy prior to the initiation of the first dialysis. The patients were stratified into quartiles according to the quartiles of serum GDF-15/Albumin ratio. Among the 159 patients, the mean age was 61.78 ± 12.52 years and median survival was 20.03 ± 7.73 months. The highest GDF-15/Albumin quartile was significantly more associated with the increased risk of all-cause mortality than other quartiles (unadjusted hazard ratio (HR): 8.468, 95% CI 2.981-24.054, p < 0.001). Older age and a higher overhydration state were associated with GDF-15/Albumin ratio. The ROC analysis confirmed that the ability of the GDF-15/Albumin ratio to predict mortality was superior to GDF-15 or albumin alone. In conclusion, the GDF-15/Albumin ratio measured at the initial maintenance hemodialysis is an independent prognostic marker of two-year mortality in ESRD patients.

Body Fat Plays an Important Role in of Bioimpedance Spectroscopy-Based Dry Weight Measurement Error for Patients with Hemodialysis.

Accurate dry weight (DW) estimation is important for hemodialysis patients. Although bioimpedance spectroscopy (BIS) is commonly used to measure DW, the BIS-based DW frequently differs from the clinical DW. We analyzed the characteristics of patients whose BIS-based DWs were over- and underestimated. In this retrospective cohort study, we evaluated 1555 patients undergoing maintenance hemodialysis in Chungnam National University Hospital. The gap (DWCP-BIS) was calculated by comparing the BIS and clinical DWs. We analyzed the clinical characteristics of patients with positive (n = 835) and negative (n = 720) gaps. Compared with other patients, the DWCP-BIS-positive group had higher extracellular water (ECW) level and extracellular/intracellular water index (E/I) and had lower weight, body mass index (BMI), lean tissue index (LTI), fat tissue index (FTI), fat mass (FAT), and adipose tissue mass (ATM). The DWCP-BIS-negative group exhibited elevated BMI, FTI, FAT, and ATM; however, it had lower height, ECW, and E/I. Linear regression analysis revealed that FAT significantly predicted DWCP accuracy. The clinical DW of patients with a low fat mass tended to be underestimated, while the clinical DW of patients with comparatively large fat reserves tended to be overestimated. These characteristics will aid in the reduction of BIS-based DW errors.