Association of Proteinuria and Hematuria with Acute Kidney Injury and Mortality in Hospitalized Patients with COVID-19

A triterpenoid (corosolic acid) ameliorated AOM-mediated aberrant crypt foci in rats: modulation of Bax/PCNA, antioxidant and inflammatory mechanisms

Corosolic acid (CA) is a well-known natural pentacyclic triterpene found in numerous therapeutic plants that can exhibit many bioactivities including anti-inflammatory and anti-tumor actions. The current investigation explores the chemoprotective roles of CA against azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) in rats. Thirty Sprague Dawley rats were grouped in 5 cages; Group A, normal control rats inoculated subcutaneously (sc) with two doses of normal saline and fed orally on 10% tween 20; Groups B-E received two doses (sc) of azoxymethane in two weeks and treated with either 10% tween 20 (group B) or two intraperitoneal injections of 35 mg/kg 5-fluorouracil each week for one month (group C), while group D and E treated with 30 and 60 mg/kg, respectively, for 2 months. The toxicity results showed lack of any behavioral abnormalities or mortality in rats ingested with up-to 500 mg/kg of CA. The present AOM induction caused a significant initiation of ACF characterized by an increased number, larger in size, and well-matured tissue clusters in cancer controls. AOM inoculation created a bizarrely elongated nucleus, and strained cells, and significantly lowered the submucosal glands in colon tissues of cancer controls compared to 5-FU or CA-treated rats. CA treatment led to significant suppression of ACF incidence, which could be mediated by its modulatory effects on the immunohistochemical proteins (pro-apoptotic (Bax) and reduced PCNA protein expressions in colon tissues). Moreover, CA-treated rats had improved oxidative stress-mediated cytotoxicity indicated by increased endogenous antioxidants (SOD and CAT) and reduced lipid peroxidation indicators (MDA). In addition, CA ingestion (30 and 60 mg/kg) suppressed the inflammatory cascades, indicated by decreased serum TNF-α and IL-6 cytokines and increased anti-inflammatory (IL-10) cytokines consequently preventing further tumor development. CA treatment maintained liver and kidney functions in rats exposed to AOM cytotoxicity. CA could be a viable alternative for the treatment of oxidative-related human disorders including ACF.

New insights into kidney disease after COVID-19 infection and vaccination: histopathological and clinical findings

In addition to its pulmonary effects, coronavirus disease 2019 (COVID-19) has also been found to cause acute kidney injury (AKI), which has been linked to high mortality rates. In this review, we collected data from 20 clinical studies on post-COVID-19-related AKI and 97 cases of AKI associated with COVID-19 vaccination. Acute tubular injury was by far the most common finding in the kidneys of patients with COVID-19-related AKI. Among patients hospitalized for COVID-19, 34.0% developed AKI, of which 59.0%, 19.1% and 21.9% were Stages 1, 2 and 3, respectively. Though kidney disease and other adverse effects after COVID-19 vaccination overall appear rare, case reports have accumulated suggesting that COVID-19 vaccination may be associated with a risk of subsequent kidney disease. Among the patients with post-vaccination AKI, the most common pathologic findings include crescentic glomerulonephritis (29.9%), acute tubular injury (23.7%), IgA nephropathy (18.6%), antineutrophil cytoplasmic autoantibody-associated vasculitis (17.5%), minimal change disease (17.5%) and thrombotic microangiopathy (10.3%). It is important to note that crescentic glomerulonephritis appears to be more prevalent in patients who have newly diagnosed renal involvement. The proportions of patients with AKI Stages 1, 2 and 3 after COVID-19 vaccination in case reports were 30.9%, 22.7% and 46.4%, respectively. In general, clinical cases of new-onset and recurrent nephropathy with AKI after COVID-19 vaccination have a positive prognosis. In this article, we also explore the underlying pathophysiological mechanisms of AKI associated with COVID-19 infection and its vaccination by describing key renal morphological and clinical features and prognostic findings.

The dynamics and outcomes of AKI progression during the COVID-19 pandemic

PURPOSE

Acute kidney injury (AKI) associated with COVID-19 is associated with poor prognosis. This study assessed the hitherto uninvestigated impact of COVID-19 on the progression and clinical outcomes of patients with AKI.

METHODS

Data from 576 patients with AKI admitted between 13/3/20 and 13/5/20 were studied. Increasingly complex analyses, from logistic regressions to competing-risk and multi-state models, have revealed insights into AKI progression dynamics associated with PCR-confirmed COVID-19 acquisition and death. Meta-analyses of case fatality ratios among patients with AKI were also conducted.

RESULTS

The overall case-fatality ratio was 0.33 [95% CI (0.20-0.36)]; higher in COVID-19 positive (COVID+) patients 0.52 [95% CI (0.46-0.58)] than in their negative (COVID-) counterparts 0.16 [95% CI (0.12-0.20)]. In AKI Stage-3 patients, that was 0.71 [95% CI (0.64-0.79)] among COVID+ patients with 45% dead within 14 days and 0.35 [95% CI (0.25-0.44)] in the COVID- group and 28% died within 14 days. Among patients diagnosed with AKI Stage-1 within 24 h, the probability of progression to AKI Stage-3 on day 7 post admission was 0.22 [95% CI (0.17-0.27)] among COVID+ patients, and 0.06 [95% CI (0.03, 0.09)] among those who tested negative. The probability of discharge by day 7 was 0.71 [95% CI (0.66, 0.75)] in COVID- patients, and 0.27 [95% CI (0.21, 0.32)] in COVID+ patients. By day 14, in AKI Stage-3 COVID+ patients, that was 0.35 [95% CI (0.25, 0.44)] with little change by day 10, that is, 0.38 [95% CI (0.29, 0.47)].

CONCLUSION

These results are consistent with either a rapid progression in severity, prolonged hospital care, or high case fatality ratio among AKI Stage-3 patients, significantly exacerbated by COVID-19 infection.

Acute kidney injury in critical COVID-19 patients: usefulness of urinary biomarkers and kidney proximal tubulopathy

Tubular injury is the main cause of acute kidney injury (AKI) in critically ill COVID-19 patients. Proximal tubular dysfunction (PTD) and changes in urinary biomarkers, such as NGAL, TIMP-2, and IGFBP7 product ([TIMP-2]•[IGFBP7]), could precede AKI. We conducted a prospective cohort study from 2020/03/09 to 2020/05/03, which consecutively included all COVID-19 patients who had at least one urinalysis, to assess the incidence of PTD and AKI, and the effectiveness of PTD, NGAL, and [TIMP-2]•[IGFBP7] in AKI and persistent AKI prediction using the area under the receiver operating characteristic curves (AUCs), Kaplan-Meier methodology (log-rank tests), and Cox models. Among the 60 patients admitted to the ICU with proven COVID-19 (median age: 63-year-old (interquartile range: IQR, 55-74), 45 males (75%), median simplified acute physiology score (SAPS) II: 34 (IQR, 22-47) and median BMI: 25.7 kg/m2 (IQR, 23.3-30.8)) analyzed, PTD was diagnosed in 29 patients (48%), AKI in 33 (55%) and persistent AKI in 20 (33%). Urinary NGAL had the highest AUC for AKI prediction: 0.635 (95%CI: 0.491-0.779) and persistent AKI prediction: 0.681 (95%CI: 0.535-0.826), as compared to PTD and [TIMP-2]•[IGFBP7] (AUCs <0.6). AKI was independently associated with higher SAPSII (HR = 1.04, 95%CI: 1.01-1.06, p = 0.005) and BMI (HR = 1.07, 95%CI: 1.00-1.14, p = 0.04) and persistent AKI with higher SAPSII (HR = 1.03, 95%CI: 1.00-1.06, p = 0.048) and nephrotoxic drug use (HR = 3.88, 95%CI: 1.20-12.5, p = 0.02). In conclusion, in critically ill COVID-19 patients, the incidence of PTD and AKI was relatively high. NGAL was the best urinary biomarker for predicting AKI, but only clinical severity was independently associated with its occurrence.

Kidney Damage in Long COVID: Studies in Experimental Mice

Signs and symptoms involving multiple organ systems which persist for weeks or months to years after the initial SARS-CoV-2 infection (also known as PASC or long COVID) are common complications of individuals with COVID-19. We recently reported pathophysiological changes in various organs post-acute infection of mice with mouse hepatitis virus-1 (MHV-1, a coronavirus) (7 days) and after long-term post-infection (12 months). One of the organs severely affected in this animal model is the kidney, which correlated well with human studies showing kidney injury post-SARS-CoV-2 infection. Our long-term post-infection pathological observation in kidneys includes the development of edema and inflammation of the renal parenchyma, severe acute tubular necrosis, and infiltration of macrophages and lymphocytes, in addition to changes observed in both acute and long-term post-infection, which include tubular epithelial cell degenerative changes, peritubular vessel congestion, proximal and distal tubular necrosis, hemorrhage in the interstitial tissue, and vacuolation of renal tubules. These findings strongly suggest the possible development of renal fibrosis, in particular in the long-term post-infection. Accordingly, we investigated whether the signaling system that is known to initiate the above-mentioned changes in kidneys in other conditions is also activated in long-term post-MHV-1 infection. We found increased TGF-β1, FGF23, NGAL, IL-18, HIF1-α, TLR2, YKL-40, and B2M mRNA levels in long-term post-MHV-1 infection, but not EGFR, TNFR1, BCL3, and WFDC2. However, only neutrophil gelatinase-associated lipocalin (NGAL) increased in acute infection (7 days). Immunoblot studies showed an elevation in protein levels of HIF1-α, TLR-2, and EGFR in long-term post-MHV-1 infection, while KIM-1 and MMP-7 protein levels are increased in acute infection. Treatment with a synthetic peptide, SPIKENET (SPK), which inhibits spike protein binding, reduced NGAL mRNA in acute infection, and decreased TGF-β1, BCL3 mRNA, EGFR, HIF1-α, and TLR-2 protein levels long-term post-MHV-1 infection. These findings suggest that fibrotic events may initiate early in SARS-CoV-2 infection, leading to pronounced kidney fibrosis in long COVID. Targeting these factors therapeutically may prevent acute or long-COVID-associated kidney complications.

Risk factors, clinical characteristics and prognostic value of acute kidney injury in COVID-19 compared with influenza virus and respiratory syncytial virus

BACKGROUND

Acute Kidney Injury (AKI) complicates a substantial part of patients with COVID-19. Direct viral penetration of renal cells through the Angiotensin Converting Enzyme 2 receptor, and indirect damage by the aberrant inflammatory response characteristic of COVID-19 are likely mechanisms. Nevertheless, other common respiratory viruses such as Influenza and Respiratory Syncytial Virus (RSV) are also associated with AKI.

METHODS

We retrospectively compared the incidence, risk factors and outcomes of AKI among patients who were admitted to a tertiary hospital because of infection with COVID-19, influenza (A + B) or RSV.

RESULTS

We collected data of 2593 patients hospitalized with COVID-19, 2041 patients with influenza and 429 with RSV. Patients affected by RSV were older, had more comorbidities and presented with higher rates of AKI at admission and within 7 days (11.7% vs. 13.3% vs. 18% for COVID-19, influenza and RSV, respectively p = 0.001). Nevertheless, patients hospitalized with COVID-19 had higher mortality (18% with COVID-19 vs. 8.6% and 13.5% for influenza and RSV, respectively P < 0.001) and higher need of mechanical ventilation (12.4% vs. 6.5% vs.8.2% for COVID-19, influenza and RSV, respectively, P = 0.002). High ferritin levels and low oxygen saturation were independent risk factors for severe AKI only in the COVID-19 group. AKI in the first 48 h of admission and in the first 7 days of hospitalization were strong independent risk factors for adverse outcome in all groups.

CONCLUSION

Despite many reports of direct kidney injury by SARS-COV-2, AKI was less in patients with COVID-19 compared to influenza and RSV patients. AKI was a prognostic marker for adverse outcome across all viruses.

Spontaneous Prostatic Hemorrhage in a COVID-19 Patient: A Case Report

Hematuria occurring in patients with acute kidney injury caused by Corona Virus Disease 2019 (COVID-19) infection has been reported. However, cases of macroscopic hematuria in COVID-19 patients leading to a severe decrease in hemoglobin have not been reported heretofore. Herein, we describe the case of a 56-year-old male patient who suffered from spontaneous prostatic hemorrhage caused by thrombocytopenia and coagulation dysfunction associated with COVID-19 infection, which manifested as macroscopic hematuria, bladder blood clot tamponade and severe hemoglobin decline. Prostatic hemorrhage was diagnosed by endoscopy. There was no recurrence of macroscopic hematuria after undergoing transurethral prostate electrocoagulation for hemostasis, infusing plasma to supplement coagulation factors and taking finasteride. One month after the bleeding event, the patient's blood routine reexamination revealed that the platelet count returned to the normal value and coagulation was normal.

Sequelae of long COVID, known and unknown: A review of updated information

Over three years have passed since the COVID-19 pandemic started. The dangerousness and impact of COVID-19 should definitely not be ignored or underestimated. Other than the symptoms of acute infection, the long-term symptoms associated with SARS-CoV-2 infection, which are referred to here as "sequelae of long COVID (LC)", are also a conspicuous global public health concern. Although such sequelae were well-documented, the understanding of and insights regarding LC-related sequelae remain inadequate due to the limitations of previous studies (the follow-up, methodological flaws, heterogeneity among studies, etc.). Notably, robust evidence regarding diagnosis and treatment of certain LC sequelae remain insufficient and has been a stumbling block to better management of these patients. This awkward situation motivated us to conduct this review. Here, we comprehensively reviewed the updated information, particularly focusing on clinical issues. We attempt to provide the latest information regarding LC-related sequelae by systematically reviewing the involvement of main organ systems. We also propose paths for future exploration based on available knowledge and the authors' clinical experience. We believe that these take-home messages will be helpful to gain insights into LC and ultimately benefit clinical practice in treating LC-related sequelae.

Association of SARS-CoV-2 viral load with biochemical profile of COVID-19 patients: A nigerian experience

Background

Kidney involvement in coronavirus disease 2019 (COVID-19) pathology has been supported by high frequency of angiotensin-converting enzyme 2 (ACE2) expression on renal cells and reports of acute kidney injury. However, the association between host viral load and kidney function is not clear.

Aim

In this study, plasma levels of renal markers (urea nitrogen, creatinine, and estimated glomerular filtration rate (eGFR)) and electrolytes (sodium, potassium, chlorine, and bicarbonate) were assessed in relation to SARS-CoV-2 viral load of COVID-19 patients.

Patients and Methods

This cross-sectional study involved 144 consenting COVID-19 patients admitted to the Ogun state COVID-19 isolation center between May and December 2020. All participants presented with mild respiratory symptoms and did not require ICU admission or ventilation support. Data included reverse transcriptase polymerase chain reaction (RT-PCR) cycle threshold (C_T) value, blood urea nitrogen (BUN), creatinine, sodium, potassium, chlorine, bicarbonate measurements, and glomerular filtration rate. Reference intervals were used as comparators, and multiple linear regression model was fitted. Statistical significance was set at P < 0.05.

Results

BUN level and creatinine were elevated in 4 (2.8%) and 42 (29.2%) patients, respectively, with lowered eGFR observed in 37 (25.7%) patients. Hyponatremia and hypokalemia were observed in 35 (24.3%) and 21 (14.6%) patients, respectively, while hypochloremia was observed in 21 (14.6%) patients. Lowered bicarbonate was observed in 29 (20.1%) patients. Linear regression showed statistically significant association (R² = 0.340, P = 0.032) between RT-PCR C_T value and eGFR (β = 0.006, P = 0.017) as well as HCO₃ (β = -0.262, P = 0.036).

Conclusion

COVID-19 patients with mild respiratory symptoms exhibited renal abnormalities, electrolytes, and acid-base imbalances which were partly associated with SARS-CoV-2 viral load.

Gross Hematuria following SARS-CoV-2 Vaccination

In the setting of the rapid development of currently available vaccines for coronavirus disease of 2019 (COVID-19), little is known about their less frequent potential side effects. Raising the awareness of clinicians and front-line healthcare workers about the less well-known potential side effects of vaccination is important. We describe the self-limited occurrence of gross hematuria in two elderly men on a combination of aspirin and another antiplatelet or anticoagulant following their second dose of the Moderna COVID-19 vaccination. While the bleeding seems to be self-limited, the long-term course currently remains elusive.

COVID-19-associated AKI

PURPOSE OF REVIEW

While it is now widely established acute kidney injury (AKI) is a common and important complication of coronavirus disease (COVID-19) disease, there is marked variability in its reported incidence and outcomes. This narrative review provides a mid-2022 summary of the latest epidemiological evidence on AKI in COVID-19.

RECENT FINDINGS

Large observational studies and meta-analyses report an AKI incidence of 28-34% in all inpatients and 46-77% in intensive care unit (ICU). The incidence of more severe AKI requiring renal replacement therapy (RRT) in ICU appears to have declined over time, in data from England and Wales RRT use declined from 26% at the start of the pandemic to 14% in 2022. The majority of survivors apparently recover their kidney function by hospital discharge; however, these individuals appear to remain at increased risk of future AKI, estimated glomerular filtration rate (eGFR) decline and chronic kidney disease. Importantly even in the absence of overt AKI a significant proportion of survivors of COVID-19 hospitalisation had reduced eGFR on follow-up.

SUMMARY

This review summarises the epidemiology, risk factors, outcomes and treatment of COVID-19-associated AKI across the global pandemic. In particular the long-term impact of COVID-19 disease on kidney health is uncertain and requires further characterisation.

Clinical Outcome and Risk Assessment in Hospitalized COVID-19 Patients with Elevated Transaminases and Acute Kidney Injury: A Single Center Study

OBJECTIVES

Initial reports indicate a high incidence of abnormal aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in patients with COVID-19 and possible association with acute kidney injury (AKI). We aimed to investigate clinical features of elevated transaminases on admission, its association with AKI, and outcomes in patients with COVID-19.

METHODS

A retrospective analysis of the registered data of hospitalized patients with laboratory-confirmed COVID-19 and assessment of the AST and ALT was performed. Multinomial logistic regression was used to determine factors associated with community-acquired AKI (CA-AKI) and hospital-acquired AKI (HA-AKI).

RESULTS

The subjects comprised 828 patients (mean age = 65.0±16.0 years; 51.4% male). Hypertension was present in 70.3% of patients, diabetes mellitus in 26.0%, and chronic kidney disease in 8.5%. In-hospital mortality was 21.0%. At admission, only 41.5% of patients had hypertransaminasemia. Patients with elevated transaminases at admission were younger, had higher levels of inflammatory markers and D-dimer, and poorer outcomes. The AKI incidence in the study population was 27.1%. Patients with hypertransaminasemia were more likely to develop AKI (33.5% vs. 23.3%, p = 0.003). Patients with predominantly elevated AST (compared to elevated ALT) were more likely to have adverse outcomes. Multinomial logistic regression found that hypertension, chronic kidney disease, elevated AST, and hematuria were associated with CA-AKI. Meanwhile, age > 65 years, hypertension, malignancy, elevated AST, and hematuria were predictors of HA-AKI.

CONCLUSIONS

Elevated transaminases on admission were associated with AKI and poor outcomes. Patients with elevated AST were more likely to have adverse outcomes. Elevated AST on admission was associated with CA-AKI and was a predictor of HA-AKI.

Acute kidney injury outcomes in covid-19 patients: systematic review and meta-analysis

BACKGROUND

Acute kidney injury (AKI) is a frequent complication of coronavirus-19 disease (COVID-19). Therefore, we decided to perform a systematic review and meta-analysis with data from the literature to relate the development of COVID-19 associated-AKI with comorbidities, medications, and the impact of mechanical ventilation.

METHODS

We performed a systematic review using the Newcastle-Ottawa scale and a meta-analysis using the R program. Relevant studies were searched in the PubMed, Medline, and SciELO electronic databases. Search filters were used to include reports after 2020 and cohort studies.

RESULTS

In total, 1166 articles were identified and 55 English-written articles were included based on the risk of bias. Of all COVID-19-hospitalized patients presenting with AKI (n = 18029) classified as Kidney Disease Improving Global Outcomes stage 1 to 3, approximately 18% required mechanical ventilation and 39.2 % died. Around 11.3% of the patients required kidney replacement therapy (KRT) and of these, 1093 died and 321 required continuous KRT. Death is more frequent in individuals with AKI [OR 6.03, 95%CI: 5.73-6.74; p<0.01]. Finally, mechanical ventilation is an aggravating factor in the clinical conditions studied [OR 11.01, 95%CI: 10.29-11.77; p<0.01].

CONCLUSION

Current literature indicates AKI as an important complication in COVID-19. In this context, we observed that comorbidities, such as chronic kidney disease and heart failure, were more related to the development of AKI. In addition, mechanical ventilation was seen as an aggravating factor in this scenario.

Acute Kidney Injury in COVID-19 Patients: Pathogenesis, Clinical Characteristics, Therapy, and Mortality

Coronavirus disease 2019 (COVID-19) is a disease caused by infection with the SARS-CoV-2 virus and has represented one of the greatest challenges humanity has faced in recent years. The virus can infect a large number of organs, including the lungs and upper respiratory tract, brain, liver, kidneys, and intestines, among many others. Although the greatest damage occurs in the lungs, the kidneys are not exempt, and acute kidney injury (AKI) can occur in patients with COVID-19. Indeed, AKI is one of the most frequent and serious organic complications of COVID-19. The incidence of COVID-19 AKI varies widely, and the exact mechanisms of how the virus damages the kidney are still unknown. For this reason, the purpose of this review was to assess current findings on the pathogenesis, clinical features, therapy, and mortality of COVID-19 AKI.

Desfechos de lesão renal aguda em pacientes com covid-19: revisão sistemática e metanálise

Resumo Antecedentes: Lesão renal aguda (LRA) é uma complicação frequente da doença do coronavírus-19 (COVID-19). Desta forma, decidimos realizar uma revisão sistemática e uma metanálise com dados da literatura para relacionar o desenvolvimento de LRA associada à COVID-19 com comorbidades, medicamentos e o impacto da ventilação mecânica. Métodos: Realizamos uma revisão sistemática usando a escala de Newcastle-Ottawa e uma metanálise utilizando o programa R. Estudos relevantes foram pesquisados nos bancos de dados eletrônicos PubMed, Medline e SciELO. Foram utilizados filtros de pesquisa para incluir relatos após 2020 e estudos de coorte. Resultados: No total, foram identificados 1166 artigos, e foram incluídos 55 artigos escritos em língua inglesa com base no risco de viés. De todos os pacientes hospitalizados por COVID-19 apresentando LRA (n = 18029) classificados como Kidney Disease Improving Global Outcomes estágios 1 a 3, aproximadamente 18% necessitaram de ventilação mecânica e 39,2% foram a óbito. Cerca de 11,3% dos pacientes necessitaram de terapia renal substitutiva (TRS) e destes, 1093 foram a óbito e 321 necessitaram de TRS contínua. O óbito é mais frequente em indivíduos com LRA [OR 6,03; IC95%: 5,73-6,74; p<0,01]. Por fim, a ventilação mecânica é um fator agravante nas condições clínicas estudadas [OR 11,01; IC95%: 10,29-11,77; p<0,01]. Conclusão: A literatura atual indica a LRA como uma complicação importante na COVID-19. Neste contexto, observamos que comorbidades, como doença renal crônica e insuficiência cardíaca, estiveram mais relacionadas ao desenvolvimento de LRA. Além disso, a ventilação mecânica foi vista como um fator agravante neste cenário.

1H NMR Signals from Urine Excreted Protein Are a Source of Bias in Probabilistic Quotient Normalization

Normalization to account for variation in urinary dilution is crucial for interpretation of urine metabolic profiles. Probabilistic quotient normalization (PQN) is used routinely in metabolomics but is sensitive to systematic variation shared across a large proportion of the spectral profile (>50%). Where ¹H nuclear magnetic resonance (NMR) spectroscopy is employed, the presence of urinary protein can elevate the spectral baseline and substantially impact the resulting profile. Using ¹H NMR profile measurements of spot urine samples collected from hospitalized COVID-19 patients in the ISARIC 4C study, we determined that PQN coefficients are significantly correlated with observed protein levels (r² = 0.423, p < 2.2 × 10^-16). This correlation was significantly reduced (r² = 0.163, p < 2.2 × 10^-16) when using a computational method for suppression of macromolecular signals known as small molecule enhancement spectroscopy (SMolESY) for proteinic baseline removal prior to PQN. These results highlight proteinuria as a common yet overlooked source of bias in ¹H NMR metabolic profiling studies which can be effectively mitigated using SMolESY or other macromolecular signal suppression methods before estimation of normalization coefficients.

COVID-19 Survival and its impact on chronic kidney disease

Up to 87% of patients hospitalized with coronavirus disease 2019 (COVID-19) experience chronic sequelae following infection. The long-term impact of COVID-19 infection on kidney function is largely unknown at this point in the COVID-19 pandemic. In this review, we highlight the current understanding of the pathophysiology of COVID-19-associated kidney injury and the impact COVID-19 may have on long-term kidney function. COVID-19-induced acute kidney injury may lead to tubular injury, endothelial injury, and glomerular injury. We highlight histopathologic correlates from large kidney biopsy and autopsy series. By conducting a comprehensive review of published literature to date, we summarize the rates of recovery from COVID-19-associated-AKI. Finally, we discuss how certain genetic differences, including APOL1 risk alleles (a risk factor for collapsing glomerulopathy), coupled with systemic healthcare disparities, may lead to a disproportionate burden of post-COVID-19-kidney function decline among racial and ethnic minority groups. We highlight the need for prospective studies to determine the true incidence of chronic kidney disease burden after COVID-19.

Short- and Long-Term Recovery after Moderate/Severe AKI in Patients with and without COVID-19

Background

Severe AKI is strongly associated with poor outcomes in coronavirus disease 2019 (COVID-19), but data on renal recovery are lacking.

Methods

We retrospectively analyzed these associations in 3299 hospitalized patients (1338 with COVID-19 and 1961 with acute respiratory illness but who tested negative for COVID-19). Uni- and multivariable analyses were used to study mortality and recovery after Kidney Disease Improving Global Outcomes Stages 2 and 3 AKI (AKI-2/3), and Machine Learning was used to predict AKI and recovery using admission data. Long-term renal function and other outcomes were studied in a subgroup of AKI-2/3 survivors.

Results

Among the 172 COVID-19-negative patients with AKI-2/3, 74% had partial and 44% complete renal recovery, whereas 12% died. Among 255 COVID-19 positive patients with AKI-2/3, lower recovery and higher mortality were noted (51% partial renal recovery, 25% complete renal recovery, 24% died). On multivariable analysis, intensive care unit admission and acute respiratory distress syndrome were associated with nonrecovery, and recovery was significantly associated with survival in COVID-19-positive patients. With Machine Learning, we were able to predict recovery from COVID-19-associated AKI-2/3 with an average precision of 0.62, and the strongest predictors of recovery were initial arterial partial pressure of oxygen and carbon dioxide, serum creatinine, potassium, lymphocyte count, and creatine phosphokinase. At 12-month follow-up, among 52 survivors with AKI-2/3, 26% COVID-19-positive and 24% COVID-19-negative patients had incident or progressive CKD.

Conclusions

Recovery from COVID-19-associated moderate/severe AKI can be predicted using admission data and is associated with severity of respiratory disease and in-hospital death. The risk of CKD might be similar between COVID-19-positive and -negative patients.

Kidney Injury in COVID-19: Epidemiology, Molecular Mechanisms and Potential Therapeutic Targets

As of December 2021, SARS-CoV-2 had caused over 250 million infections and 5 million deaths worldwide. Furthermore, despite the development of highly effective vaccines, novel variants of SARS-CoV-2 continue to sustain the pandemic, and the search for effective therapies for COVID-19 remains as urgent as ever. Though the primary manifestation of COVID-19 is pneumonia, the disease can affect multiple organs, including the kidneys, with acute kidney injury (AKI) being among the most common extrapulmonary manifestations of severe COVID-19. In this article, we start by reflecting on the epidemiology of kidney disease in COVID-19, which overwhelmingly demonstrates that AKI is common in COVID-19 and is strongly associated with poor outcomes. We also present emerging data showing that COVID-19 may result in long-term renal impairment and delve into the ongoing debate about whether AKI in COVID-19 is mediated by direct viral injury. Next, we focus on the molecular pathogenesis of SARS-CoV-2 infection by both reviewing previously published data and presenting some novel data on the mechanisms of cellular viral entry. Finally, we relate these molecular mechanisms to a series of therapies currently under investigation and propose additional novel therapeutic targets for COVID-19.

Using dipstick urinalysis to predict development of acute kidney injury in patients with COVID-19

BACKGROUND

Acute kidney injury (AKI) is a common complication in patients hospitalized with COVID-19 and may require renal replacement therapy (RRT). Dipstick urinalysis is frequently obtained, but data regarding the prognostic value of hematuria and proteinuria for kidney outcomes is scarce.

METHODS

Patients with positive severe acute respiratory syndrome-coronavirus 2 (SARS-CoV2) PCR, who had a urinalysis obtained on admission to one of 20 hospitals, were included. Nested models with degree of hematuria and proteinuria were used to predict AKI and RRT during admission. Presence of Chronic Kidney Disease (CKD) and baseline serum creatinine were added to test improvement in model fit.

RESULTS

Of 5,980 individuals, 829 (13.9%) developed an AKI during admission, and 149 (18.0%) of those with AKI received RRT. Proteinuria and hematuria degrees significantly increased with AKI severity (P < 0.001 for both). Any degree of proteinuria and hematuria was associated with an increased risk of AKI and RRT. In predictive models for AKI, presence of CKD improved the area under the curve (AUC) (95% confidence interval) to 0.73 (0.71, 0.75), P < 0.001, and adding baseline creatinine improved the AUC to 0.85 (0.83, 0.86), P < 0.001, when compared to the base model AUC using only proteinuria and hematuria, AUC = 0.64 (0.62, 0.67). In RRT models, CKD status improved the AUC to 0.78 (0.75, 0.82), P < 0.001, and baseline creatinine improved the AUC to 0.84 (0.80, 0.88), P < 0.001, compared to the base model, AUC = 0.72 (0.68, 0.76). There was no significant improvement in model discrimination when both CKD and baseline serum creatinine were included.

CONCLUSIONS

Proteinuria and hematuria values on dipstick urinalysis can be utilized to predict AKI and RRT in hospitalized patients with COVID-19. We derived formulas using these two readily available values to help prognosticate kidney outcomes in these patients. Furthermore, the incorporation of CKD or baseline creatinine increases the accuracy of these formulas.

Can microalbuminuria be an ındicator of renal ınvolvement in pediatric Covid 19 patients?

Background

Proteinuria (both tubular and glomerular in origin) and its implications are well-known features of adult patients with COVID19. However currently studies addressing proteinuria and its role in the outcome of kidney and patients of pediatric COVID 19 is scarce. We aimed to evaluate the presence of microalbuminuria in order to detect early renal involvement in pediatric COVID 19 patients.

Methods

We prospectively evaluated 100 pediatric patients hospitalized with COVID 19 between April and July 2020. Clinical presentations, laboratory findings and outcomes were investigated. Microalbuminuria was compared with the age, gender, disease severity, and hemoglobin, platelet, leukocyte count and serum CRP levels of the patients.

Results

Twenty seven out of 100 patients had microalbuminuria. Fourteen patients had mild and fourteen had moderate disease. There was not any significant relation according to age and gender. Microalbuminuria was not related to the severity of the disease. Also the mean microalbuminuria level did not differ according to the disease course. Hemoglobin, platelet, leukocyte counts and serum CRP levels were also were not correlated with microalbuminuria levels.

Conclusion

Although there was no difference between the groups with different disease course; microalbuminuria is detected in an important ratio of pediatric patients with COVID 19 in this study. In the highlight of our findings we suggest that urinary findings of pediatric COVID patients should be carefully evaluated.

Recent Advances in Kidney Bioengineering

Kidney disease is an epidemic that affects more than 600 million people worldwide. The socioeconomic impacts of the disease disproportionately affect Hispanic and non-Hispanic Black Americans, making the disease an issue of social inequality. The urgency of this situation has only become worse during the COVID-19 pandemic, as those who are hospitalized for COVID-19 have an increased risk of kidney failure. For researchers, the kidney is a complex organ that is difficult to accurately model and understand. Traditional cell culture models are not adequate for studying the functional intricacies of the kidney, but recent experiments have offered improvements for understanding these systems. Recent progress includes organoid modeling, 3D bioprinting, decellularization, and microfluidics. Here, we offer a review of the most recent advances in kidney bioengineering.

Acute Kidney Injury and Renal Replacement Therapy in COVID-19 Versus Other Respiratory Viruses: A Systematic Review and Meta-Analysis

BACKGROUND

Acute kidney injury (AKI) is a potentially fatal complication of Coronavirus Disease-2019 (COVID-19). Binding of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19, to its viral receptor, angiotensin converting enzyme 2 (ACE2), results in viral entry and may cause AKI.

OBJECTIVES

We performed a systematic review and meta-analysis of the frequencies of AKI and renal replacement therapy (RRT) in critically ill COVID-19 patients and compared those frequencies with patients who were infected by respiratory viruses that bind or downregulate ACE2 (ACE2-associated viruses) and viruses that do not bind nor downregulate ACE2 (non-ACE2-associated viruses).

DESIGN

Systematic review and meta-analysis.

SETTING

Observational studies on COVID-19 and other respiratory viral infections reporting AKI and RRT were included. The exclusion criteria were non-English articles, non-peer-reviewed articles, review articles, studies that included patients under the age of 18, studies including fewer than 10 patients, and studies not reporting AKI and RRT rates.

PATIENTS

Adult COVID-19, Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS), and influenza patients.

MEASUREMENTS

We extracted the following data from the included studies: author, year, study location, age, sex, race, diabetes mellitus, hypertension, chronic kidney disease, shock, vasopressor use, mortality, intensive care unit (ICU) admission, ICU mortality, AKI, and RRT.

METHODS

We systematically searched PubMed and EMBASE for articles reporting AKI or RRT. AKI was defined by authors of included studies. Critical illness was defined by ICU admission. We performed a random effects meta-analysis to calculate pooled estimates for the AKI and RRT rate within each virus group using a random intercept logistic regression model.

RESULTS

Of 23 655 hospitalized, critically ill COVID-19 patients, AKI frequencies were not significantly different between COVID-19 patients (51%, 95% confidence interval [CI]: 44%-57%) and critically ill patients infected with ACE2-associated (56%, 95% CI: 37%-74%, P = .610) or non-ACE2-associated viruses (63%, 95% CI: 43%-79%, P = .255). Pooled RRT rates were also not significantly different between critically ill, hospitalized patients with COVID-19 (20%, 95% CI: 16%-24%) and ACE2-associated viruses (18%, 95% CI: 8%-33%, P = .747). RRT rates for both COVID-19 and ACE2-associated viruses were significantly different (P < .001 for both) from non-ACE2-associated viruses (49%, 95% CI: 44%-54%). After adjusting for shock or vasopressor use, AKI and RRT rates were not significantly different between groups.

LIMITATIONS

Limitations of this study include the heterogeneity of definitions of AKI that were used across different virus studies. We could not match severity of infection or do propensity matching across studies. Most of the included studies were conducted in retrospective fashion. Last, we did not include non-English publications.

CONCLUSIONS

Our findings suggest that viral ACE2 association does not significantly alter the rates of AKI and RRT among critically ill patients admitted to the ICU. However, the rate of RRT is lower in patients with COVID-19 or ACE2-associated viruses when compared with patients infected with non-ACE2-binding viruses, which might partly be due to the lower frequencies of shock and use of vasopressors in these two virus groups. Prospective studies are necessary to demonstrate whether modulation of the ACE2 axis with Renin-Angiotensin System inhibitors impacts the rates of AKI and whether they are beneficial or harmful in COVID-19 patients.

Frequency and factors associated with proteinuria in COVID-19 patients: a cross-sectional study

Proteinuria is a marker of severity and poor outcome of patients in intensive care unit (ICU). The objective of this study was to determine the frequency of proteinuria and the risk factors associated with proteinuria in Congolese COVID-19 patients. The present cross sectional study of proteinuria status is a post hoc analysis of data from 80 COVID-19 patients admitted at Kinshasa Medical Center (KMC) from March 10th to July 10th, 2020. The population under study came from all adult inpatients (≥18 years old) with a laboratory diagnosis by polymerase chain reaction (PCR) of COVID-19 were selected and divided into two groups (positive proteinuria and negative proteinuria group). Logistic regression models helped to identify the factors associated with proteinuria. The P value significance level was 0.05. Among 80 patients who tested positive for SARS-CoV-2 RT-PCR, 55% had proteinuria. The mean age was 55.2 ± 12.8 years. Fourty-seven patients (58.8%) had history of hypertension and 26 patients (32.5%) diabetes. Multivariable analysis showed age ≥ 65 years (aOR 5,04; 95% CI: 1.51-16.78), diabetes (aOR 3,15; 95% CI: 1.14-8.72), ASAT >40 UI/L (aOR 7,08; 95% CI: 2.40-20.87), ferritin >300 (aOR 13,47; 95% CI: 1.56-26.25) as factors independently associated with proteinuria in COVID-19 patients. Proteinuria is common in Congolese COVID-19 patients and is associated with age, diabetes, ferritin and aspartate aminotransferase (ASAT).

Association of AKI-D with Urinary Findings and Baseline eGFR in Hospitalized COVID-19 Patients

Background

AKI is common in patients hospitalized with coronavirus disease 2019 (COVID-19). Risk factors for AKI requiring dialysis (AKI-D) are not fully understood. We aimed to identify risk factors associated with AKI-D and AKI not requiring dialysis (AKI-ND).

Methods

We reviewed electronic health records of 3186 patients aged ≥18 years old who were hospitalized with COVID-19 across six hospitals. Patient characteristics, urinalysis findings, and inflammatory markers were analyzed for association with in-hospital AKI status (AKI-D, AKI-ND, or no AKI), and we subsequently evaluated mortality.

Results

After adjustment for multiple covariates, higher baseline eGFR was associated with 30% lower odds of AKI-D and 11% lower odds of AKI-ND (for AKI-D, OR, 0.70; 95% CI, 0.64 to 0.77; for AKI-ND, OR, 0.89; 95% CI, 0.85 to 0.92). Patients with obesity and those who were Latino had increased odds of AKI-D, whereas patients with congestive heart failure or diabetes with complications had increased odds of AKI-ND. Females had lower odds of in-hospital AKI (for AKI-D, OR, 0.28; 95% CI, 0.17 to 0.46; for AKI-ND, OR, 0.83; 95% CI, 0.70 to 0.99). After adjustment for covariates and baseline eGFR, 1-4+ protein on initial urinalysis was associated with a nine-fold increase in odds of AKI-D (OR, 9.00; 95% CI, 2.16 to 37.38) and more than two-fold higher odds of AKI-ND (OR, 2.28; 95% CI, 1.66 to 3.13). Findings of 1-3+ blood and trace glucose on initial urinalysis were also associated with increased odds of both AKI-D and AKI-ND. AKI-D and AKI-ND were associated with in-hospital death (for AKI-D, OR, 2.64; 95% CI, 1.13 to 6.17; for AKI-ND, OR, 2.44; 95% CI, 1.77 to 3.35).

Conclusions

Active urine sediments, even after adjustment for baseline kidney function, and reduced baseline eGFR are significantly associated with increased odds of AKI-D and AKI-ND. In-hospital AKI was associated with in-hospital death. These findings may help prognosticate patients hospitalized with COVID-19.

Angiotensin-Converting Enzyme 2 in the Pathogenesis of Renal Abnormalities Observed in COVID-19 Patients

Coronavirus disease 2019 (COVID-19) was first reported in late December 2019 in Wuhan, China. The etiological agent of this disease is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the high transmissibility of the virus led to its rapid global spread and a major pandemic (ongoing at the time of writing this review). The clinical manifestations of COVID-19 can vary widely from non-evident or minor symptoms to severe acute respiratory syndrome and multi-organ damage, causing death. Acute kidney injury (AKI) has been recognized as a common complication of COVID-19 and in many cases, kidney replacement therapy (KRT) is required. The presence of kidney abnormalities on hospital admission and the development of AKI are related to a more severe presentation of COVID-19 with higher mortality rate. The high transmissibility and the broad spectrum of clinical manifestations of COVID-19 are in part due to the high affinity of SARS-CoV-2 for its receptor, angiotensin (Ang)-converting enzyme 2 (ACE2), which is widely expressed in human organs and is especially abundant in the kidneys. A debate on the role of ACE2 in the infectivity and pathogenesis of COVID-19 has emerged: Does the high expression of ACE2 promotes higher infectivity and more severe clinical manifestations or does the interaction of SARS-CoV-2 with ACE2 reduce the bioavailability of the enzyme, depleting its biological activity, which is closely related to two important physiological systems, the renin-angiotensin system (RAS) and the kallikrein-kinin system (KKS), thereby further contributing to pathogenesis. In this review, we discuss the dual role of ACE2 in the infectivity and pathogenesis of COVID-19, highlighting the effects of COVID-19-induced ACE2 depletion in the renal physiology and how it may lead to kidney injury. The ACE2 downstream regulation of KKS, that usually receives less attention, is discussed. Also, a detailed discussion on how the triad of symptoms (respiratory, inflammatory, and coagulation symptoms) of COVID-19 can indirectly promote renal injury is primary aborded.

The Risk Factors and Clinical Outcomes Associated with Acute Kidney Injury in Patients with COVID-19: Data from a Large Cohort in Iran

INTRODUCTION

Kidney involvement, ranging from mild hematuria and proteinuria to acute kidney injury (AKI) in patients with coronavirus disease-2019 (COVID-19), is a recent finding with various incidence rates reported among hospitalized patients with COVID-19. Given the various AKI rates and their associated risk factors, lack of AKI recovery in the majority of patients hospitalized with COVID-19, and limited data regarding AKI in patients with COVID-19 in Iran, we aim to investigate the potential risk factors for AKI development and its incidence in patients hospitalized with COVID-19.

METHODS

In this retrospective cohort study, we enrolled adult patients referred to the Sina Hospital, Iran, from February 20 to May 14, 2020, with either a positive PCR test or a highly susceptible chest computed tomography features consistent with COVID-19 diagnosis. AKI was defined according to the kidney disease improving global outcomes criteria, and patients were stratified based on their AKI staging. We evaluated the risk indicators associated with AKI during hospitalization besides in-hospital outcomes and recovery rate at the time of discharge.

RESULTS

We evaluated 516 patients with a mean age of 57.6 ± 16.1 years and a male-to-female ratio of 1.69 who were admitted with the COVID-19 diagnosis. AKI development was observed among 194 (37.6%) patients, comprising 61.9% patients in stage 1, 18.0% in stage 2, and 20.1% in stage 3. Out of all patients, AKI occurred in 58 (11.2%) patients during the hospital course, and 136 (26.3%) patients arrived with AKI upon admission. AKI development was positively associated with all of the in-hospital outcomes, including intensive care unit admissions, need for invasive ventilation, acute respiratory distress syndrome (ARDS), acute cardiac injury, acute liver injury, multiorgan damage, and mortality. Patients with stage 3 AKI showed a significantly higher mortality rate, ARDS, and need for invasive ventilation than other stages. After multivariable analysis, male sex (odds ratio [OR]: 11.27), chronic kidney disease (CKD) (OR: 6.89), history of hypertension (OR: 1.69), disease severity (OR: 2.27), and high urea levels (OR: 1.04) on admission were independent risk indicators of AKI development. Among 117 (28.1%) patients who experienced AKI and survived, only 33 (28.2%) patients made a recovery from the AKI, and 84 (71.8%) patients did not exhibit full recovery at the time of discharge.

DISCUSSION/CONCLUSION

We found that male sex, history of CKD, hypertension, disease severity, and high serum urea were independent risk factors associated with AKI in patients with COVID-19. Also, higher stages of AKI were associated with increased risk of mortality and in-hospital complications. Our results indicate a necessity for more precise care and monitoring for AKI during hospitalization in patients with COVID-19, and lack of AKI recovery at the time of discharge is a common complication in such patients.

Manifestations of renal system involvement in hospitalized patients with COVID-19 in Saudi Arabia

BACKGROUND

Although COVID-19 is an acute disease that usually resolves rapidly in most cases, the disease can be fatal and has a mortality rate of about 1% to 56%. Alveolar injury and respiratory failure are the main causes of death in patients with COVID 19. In addition, the effect of the disease on other organs is not fully understood. Renal system affection has been reported in patients with COVID 19 and is associated with a higher rate of diverse outcomes, including mortality. Therefore, in the present work, we reported the clinical characteristics and laboratory data of hospitalized patients with COVID-19 and analyzed the manifestations that indicated renal system involvement and their impact on clinical outcomes.

MATERIALS AND METHODS

This was an observational retrospective study conducted at King Fahd Specialist Hospital, Buraydah, Saudi Arabia. All patients with COVID-19 who were admitted to this Hospital from April to December 2020 were included in the study. The patients' findings at presentation were recorded. Demographic data and laboratory results (hematuria, proteinuria, urinary sediment cast and pus cell presence, and kidney function tests) were retrieved from electronic patient records.

RESULTS

One hundred and ninety-three patients with confirmed COVID 19 were included in the study. Dipstick examinations of all urine samples showed proteinuria and hematuria in 53.9% and 22.3% of patients, respectively, whereas microscopic examination revealed the presence of pus and brown muddy granular casts in 33.7% and 12.4% of samples, respectively. Acute kidney injury was reported in 23.3% of patients. A multivariable analysis demonstrated that hematuria was associated with acute kidney injury (AKI) (OR, 2.4; 95% CI, 1.2-4.9; P = 0.001), ICU admission (OR, 3.789; 95% CI, 1.913-7.505; P = 0.003), and mortality (OR, 8.084; 95% CI, 3.756-17.397; P = 0.002). Conversely, proteinuria was less significantly associated with the risk of AKI (OR, 1.56; 95% CI, 1.91-7.50; P = 0.003), ICU admission (OR, 2.493; 95% CI, 1.25-4.72; P = 0.001), and mortality (OR, 2.764; 95% CI, 1.368-5.121; P = 0.003). Patients with AKI had a higher probability for mortality than did those without AKI (OR, 14.208; 95% CI, 6.434-31.375; P = 0.003).

CONCLUSION

The manifestations of the involvement of the renal system are not uncommon in COVID-19. These manifestations included proteinuria, hematuria, and AKI and were usually associated with a poor prognosis, including high incidences of both ICU admission and mortality.

Current Understanding of Clinical Manifestations of COVID-19 in Glomerular Disease

Background

The novel coronavirus disease (COVID-19), also known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an evolving pandemic with significant mortality. Information about the impact of infection on glomerular disease patients in particular has been lacking. Understanding the virus's effect in glomerular disease is constantly changing. This review article summarizes the data published thus far on COVID-19 and its manifestations in pre-existing and de novo glomerular disease.

Summary

While patients with glomerular disease may be at higher risk of severe COVID-19 due to their immunosuppressed status, some data suggest that a low amount of immunosuppression may be helpful in mitigating the systemic inflammatory response which is associated with high mortality rates in COVID-19. There have been a few case reports on COVID-19 causing glomerular disease relapse in patients. Multiple mechanisms have been proposed for kidney injury, proteinuria, and hematuria in the setting of COVID-19. More commonly, these are caused by direct tubular injury due to hemodynamic instability and hypoxic injury. However, the cytokine storm induced by COVID-19 may trigger common post-viral glomerular disease such as IgA nephropathy, anti-GBM, and ANCA vasculitis that have also been described in COVID-19 patients. Collapsing glomerulopathy, a hallmark of HIV-associated nephropathy, is being reported SARS-CoV-2 cases, particularly in patients with high-risk APOL1 alleles. Direct viral invasion of glomerular structures is hypothesized to cause a podocytopathy due to virus's affinity to ACE2, but evidence for this remains under study.

Key Messages

Infection with SARS-CoV-2 may cause glomerular disease in certain patients. The mechanism of de novo glomerular disease in the setting of COVID-19 is under study. The management of patients with existing glomerular disease poses unique challenges, especially with regard to immunosuppression management. Further studies are needed to inform clinician decisions about the management of these patients during the COVID-19 pandemic.

Pathophysiology and Clinical Manifestations of COVID-19-Related Acute Kidney Injury-The Current State of Knowledge and Future Perspectives

The continually evolving severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has resulted in a vast number of either acute or chronic medical impairments of a pathophysiology that is not yet fully understood. SARS-CoV-2 tropism for the organs is associated with bilateral organ cross-talks as well as targeted dysfunctions, among which acute kidney injury (AKI) seems to be highly prevalent in infected patients. The need for efficient management of COVID-related AKI patients is an aspect that is still being investigated by nephrologists; however, another reason for concern is a disturbingly high proportion of various types of kidney dysfunctions in patients who have recovered from COVID-19. Even though the clinical picture of AKI and COVID-related AKI seems to be quite similar, it must be considered that regarding the latter, little is known about both the optimal management and long-term consequences. These discrepancies raise an urgent need for further research aimed at evaluating the molecular mechanisms associated with SARS-CoV-2-induced kidney damage as well as standardized management of COVID-related AKI patients. The following review presents a comprehensive and most-recent insight into the pathophysiology, clinical manifestations, recommended patient management, treatment strategies, and post-mortem findings in patients with COVID-related AKI.

Challenges in defining Long COVID: Striking differences across literature, Electronic Health Records, and patient-reported information

Since late 2019, the novel coronavirus SARS-CoV-2 has introduced a wide array of health challenges globally. In addition to a complex acute presentation that can affect multiple organ systems, increasing evidence points to long-term sequelae being common and impactful. The worldwide scientific community is forging ahead to characterize a wide range of outcomes associated with SARS-CoV-2 infection; however the underlying assumptions in these studies have varied so widely that the resulting data are difficult to compareFormal definitions are needed in order to design robust and consistent studies of Long COVID that consistently capture variation in long-term outcomes. Even the condition itself goes by three terms, most widely "Long COVID", but also "COVID-19 syndrome (PACS)" or, "post-acute sequelae of SARS-CoV-2 infection (PASC)". In the present study, we investigate the definitions used in the literature published to date and compare them against data available from electronic health records and patient-reported information collected via surveys. Long COVID holds the potential to produce a second public health crisis on the heels of the pandemic itself. Proactive efforts to identify the characteristics of this heterogeneous condition are imperative for a rigorous scientific effort to investigate and mitigate this threat.

Proteinuria in COVID-19

Upper respiratory and pulmonary diseases are the primary manifestations of coronavirus disease 2019 (COVID-19). However, kidney involvement has also been recognized and extensively described. A large percentage of affected patients present with acute kidney injury (AKI). However, specific phenotypic aspects of AKI or other renal manifestations of COVID-19 remain sparsely characterized. Many reports indicate that proteinuria can be detected in AKI associated with COVID-19 (CoV-AKI) despite CoV-AKI being largely described as a form of acute tubular injury. On the other hand, individuals of African ancestry with the high-risk APOL1 genotype are uniquely at risk of developing collapsing glomerulopathy when they are infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the entity now known as COVID-19-associated nephropathy (COVAN). Patients with COVAN typically present with nephrotic-range proteinuria. The exact incidence of proteinuria in COVID-19 is unclear due to heterogeneity in the frequency with which proteinuria has been assessed in cases of COVID-19, as well as methodological differences in the way proteinuria is measured and/or reported. In this review we discuss the current evidence of proteinuria as a manifestation of COVID-19 and elaborate on potential pathophysiological mechanisms associated with it.