Abstract
Long coronavirus disease (Long COVID, post-acute sequelae of SARS-CoV-2 infection [PASC]) has emerged as a major chronic health challenge affecting multiple organ systems. Although pulmonary, cardiovascular, and neurologic manifestations have received substantial attention, increasing evidence indicates that the kidney represents an important target of both acute and chronic SARS-CoV-2-mediated injury. Renal sequelae may occur following severe acute kidney injury (AKI) during acute infection, but kidney dysfunction has also been documented following apparently mild disease. Persistent reductions in estimated glomerular filtration rate (eGFR), proteinuria, glomerular disease, endothelial dysfunction, microvascular injury, and progressive chronic kidney disease (CKD) have been reported among survivors.
Current evidence suggests that renal Long COVID arises from a multifactorial interaction involving viral persistence, immune dysregulation, endothelial injury, complement activation, mitochondrial dysfunction, thromboinflammation, maladaptive repair pathways, and host genetic susceptibility. Genomic investigations have identified potential contributions from interferon signaling pathways, HLA-associated immune regulation, APOL1 risk variants, and inflammatory transcriptomic signatures. Patients with pre-existing CKD appear particularly vulnerable to Long COVID, whereas COVID vaccination appears associated with a reduced risk of severe disease and Long COVID development. Rare reports of vaccine-associated glomerular disease have been described, although causality remains uncertain.
This review summarizes current understanding of the etiology, pathology, genomics, physiology, clinical presentation, management considerations, and long-term implications of renal Long COVID.
Introduction
More than six years after the emergence of SARS-CoV-2, attention has increasingly shifted from acute infection toward the chronic consequences of COVID-19. Long COVID is generally defined as symptoms and pathophysiologic abnormalities persisting for at least three months following acute infection and not explained by alternative diagnoses. The syndrome affects multiple organ systems and exhibits remarkable heterogeneity. Increasing evidence demonstrates that renal involvement represents a significant component of Long COVID.
Kidney injury during acute COVID-19 was recognized early in the pandemic. Hospitalized patients frequently developed AKI, proteinuria, hematuria, and electrolyte disturbances. Subsequent longitudinal studies revealed that kidney dysfunction may persist long after apparent recovery from acute infection. Even individuals who never required hospitalization can exhibit accelerated declines in renal function months or years later.
The public health implications are substantial. CKD already affects hundreds of millions of individuals worldwide. Even modest increases in CKD incidence attributable to Long COVID could translate into a major future burden of dialysis dependence, cardiovascular disease, and premature mortality.
Etiology of Renal Long COVID
The pathogenesis of renal Long COVID appears multifactorial.
Viral Persistence
One leading hypothesis proposes persistence of viral antigens or viral reservoirs in tissues following acute infection.
SARS-CoV-2 demonstrates tropism for renal tissues because ACE2 receptors are highly expressed on:
- Proximal tubular epithelial cells
- Podocytes
- Renal endothelial cells
- Collecting duct epithelium
Persistent viral antigens may maintain chronic inflammatory signaling and promote ongoing tissue injury. Evidence of viral RNA and protein persistence in various tissues months after infection supports this hypothesis, although definitive demonstration within kidneys remains an area of active investigation.
Endothelial Dysfunction
Endothelial injury appears central to Long COVID pathophysiology.
SARS-CoV-2 infection produces:
- Endothelial activation
- Loss of glycocalyx integrity
- Increased vascular permeability
- Platelet activation
- Microvascular thrombosis
The renal microcirculation is particularly vulnerable because of its extensive capillary network and high blood flow requirements.
Persistent endothelial dysfunction may lead to:
- Chronic hypoperfusion
- Tubulointerstitial fibrosis
- Progressive nephron loss
- Accelerated CKD progression
Immune Dysregulation
Long COVID is characterized by persistent immune activation.
Observed abnormalities include:
- Elevated inflammatory cytokines
- Dysregulated T-cell responses
- B-cell abnormalities
- Autoantibody formation
- Complement activation
These immune abnormalities may contribute directly to glomerular injury and chronic inflammation.
Persistent elevations in:
- IL-6
- TNF-α
- IFN-γ
have been implicated in ongoing tissue damage.
Thromboinflammatory Mechanisms
COVID-19 produces profound disturbances of coagulation.
Mechanisms include:
- Platelet hyperactivation
- Complement-mediated thrombosis
- Fibrin amyloid microclot formation
- Endothelial injury
Microvascular obstruction may contribute to chronic renal ischemia and nephron loss.
Persistent thromboinflammatory pathways remain a major area of Long COVID research.
Renal Pathology
Acute Tubular Injury
The most common renal lesion during acute infection is acute tubular injury.
Histopathologic findings include:
- Tubular epithelial degeneration
- Loss of brush borders
- Tubular dilation
- Cast formation
- Interstitial inflammation
Incomplete repair may result in chronic fibrosis and nephron loss.
COVID-Associated Nephropathy (COVAN)
One of the most distinctive renal pathologies linked to COVID is COVID-associated nephropathy.
Features include:
- Collapsing focal segmental glomerulosclerosis
- Podocyte injury
- Severe proteinuria
- Rapid loss of renal function
COVAN occurs predominantly among individuals carrying high-risk APOL1 variants and demonstrates striking genetic susceptibility.
Glomerular Disease
Reported glomerular disorders include:
- Minimal change disease
- IgA nephropathy
- Membranous nephropathy
- ANCA-associated vasculitis
- FSGS
The precise relationship between Long COVID and these disorders remains under investigation.
Fibrosis
Progressive fibrosis appears to be a final common pathway.
Persistent injury activates:
- TGF-β
- Fibroblast proliferation
- Extracellular matrix deposition
Resulting changes include:
- Interstitial fibrosis
- Tubular atrophy
- Permanent nephron loss
Genomics
APOL1 Risk Variants
APOL1 high-risk genotypes are strongly associated with COVID-associated nephropathy.
Individuals carrying:
- G1 allele
- G2 allele
appear disproportionately susceptible to collapsing glomerulopathy.
This observation represents one of the strongest genetic associations identified in COVID-related kidney disease.
Interferon Signaling
Transcriptomic studies demonstrate persistent activation of interferon pathways.
Genes involved include:
- IFITM family
- OAS family
- STAT signaling components
Chronic activation may contribute to ongoing inflammation and tissue injury.
HLA Associations
Emerging evidence suggests certain HLA haplotypes may influence:
- Long COVID susceptibility
- Autoimmune responses
- Vaccine responses
- Renal manifestations
Further research remains necessary.
Mitochondrial Genomics
Mitochondrial dysfunction is increasingly recognized in Long COVID.
Observed abnormalities include:
- Reduced ATP generation
- Oxidative stress
- Altered metabolic signaling
These changes may contribute to both systemic symptoms and renal dysfunction.
Physiology
Renin-Angiotensin System Dysregulation
ACE2 serves as the cellular receptor for SARS-CoV-2.
ACE2 normally counterbalances:
- Angiotensin II
- Vasoconstriction
- Fibrosis
- Inflammation
Disruption of ACE2 signaling may promote:
- Renal vasoconstriction
- Hypertension
- Fibrosis
Microvascular Dysfunction
Persistent endothelial injury contributes to:
- Impaired autoregulation
- Reduced perfusion
- Tissue hypoxia
The kidney’s dependence on precise microvascular regulation makes it particularly susceptible.
Mitochondrial Dysfunction
Renal tubular cells possess high energy requirements.
Mitochondrial injury can produce:
- ATP depletion
- Oxidative stress
- Tubular dysfunction
These mechanisms may contribute to persistent reductions in renal reserve.
Clinical Manifestations
Reported renal manifestations include:
Proteinuria
Often the earliest sign.
Hematuria
May indicate glomerular involvement.
Reduced eGFR
Persistent declines in renal filtration have been documented months after infection.
Chronic Kidney Disease
Progressive CKD appears to represent one of the most important long-term outcomes.
Hypertension
Commonly accompanies post-COVID renal dysfunction.
Electrolyte Abnormalities
Including disturbances in:
- Sodium
- Potassium
- Acid-base balance
COVID Vaccination and Kidney Injury
The literature concerning vaccine-associated renal disease requires careful interpretation.
Reported Events
Case reports have described:
- IgA nephropathy flares
- Minimal change disease
- Membranous nephropathy
- ANCA vasculitis
- Relapses of pre-existing glomerular disorders
These reports demonstrate temporal associations but do not necessarily establish causation.
Current Evidence
Recent nephrology reviews conclude:
- No proven causal association exists between SARS-CoV-2 vaccination and most glomerular diseases.
- Vaccine-associated renal events appear rare.
- Benefits substantially outweigh risks.
- Vaccination is associated with reduced severe COVID risk and lower Long COVID risk.
Proposed Mechanisms
Hypothesized mechanisms include:
- Immune activation
- Cytokine release
- Molecular mimicry
- Triggering of previously silent autoimmune disease
Evidence remains limited.
Clinical Evaluation
Recommended assessment includes:
Laboratory Testing
- Serum creatinine
- eGFR
- Urinalysis
- Urine albumin-creatinine ratio
- Electrolytes
Imaging
- Renal ultrasound
- CT or MRI when indicated
Biopsy
Appropriate when:
- Nephrotic syndrome develops
- Rapid renal decline occurs
- Glomerular disease is suspected
Management
Currently no therapy is specifically approved for renal Long COVID.
Management focuses on:
Blood Pressure Control
ACE inhibitors or ARBs when indicated.
Proteinuria Reduction
Renoprotective therapies should be optimized.
Cardiovascular Risk Reduction
Aggressive management of:
- Diabetes
- Hypertension
- Hyperlipidemia
CKD Monitoring
Serial measurement of:
- eGFR
- Albuminuria
- Blood pressure
Long-Term Implications
The long-term burden of renal Long COVID remains uncertain but potentially substantial.
Potential consequences include:
Increased CKD Prevalence
Even modest declines in eGFR may have population-level significance.
Greater Dialysis Demand
Progressive nephron loss may increase end-stage kidney disease incidence.
Cardiovascular Disease
CKD remains a powerful cardiovascular risk factor.
Economic Burden
Long-term monitoring, medications, and renal replacement therapy create substantial healthcare costs.
Reduced Quality of Life
Fatigue, cognitive dysfunction, and CKD often coexist in Long COVID patients.
Conclusions
Accumulating evidence indicates that the kidney is an important target organ in Long COVID. Persistent renal dysfunction appears to result from a complex interplay of viral persistence, endothelial injury, thromboinflammation, immune dysregulation, mitochondrial dysfunction, maladaptive repair pathways, and genetic susceptibility. Long-term consequences may include accelerated CKD progression, cardiovascular morbidity, and increased healthcare burden. Current evidence supports vigilant monitoring of renal function following SARS-CoV-2 infection, particularly among individuals with prior AKI, CKD, diabetes, hypertension, or other risk factors. Although rare vaccine-associated renal syndromes have been reported, contemporary nephrology reviews conclude that convincing evidence for widespread vaccine-induced kidney injury is lacking and that vaccination remains protective against severe COVID-19 and Long COVID. Further prospective studies integrating genomics, transcriptomics, proteomics, and renal pathology will be essential to define mechanisms and identify targeted therapies.
Key References
- Ivković V, et al. Long COVID and the kidney. Nature Reviews Nephrology. 2025.
- Frediani MM, et al. Renal Long COVID: A Scoping Review. Kidney Medicine. 2025.
- da Silva M, et al. Advances in Understanding Long COVID: Pathophysiological Mechanisms and the Role of Omics Technologies in Biomarker Identification. 2025.
- Wang D, Zhang F. CKD-related impairment in humoral and cellular immune response and potential correlation with Long COVID-19. Frontiers in Immunology. 2025.