Kidney Involvement in Patients with the Omicron Variant of COVID-19


Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to pose significant challenges to global health.

The disease manifests with severe pulmonary symptoms, but emerging evidence suggests its impact extends to various organ systems, including the kidneys. While the novel Omicron variant of SARS-CoV-2 has garnered attention for its heightened transmissibility and evasion of immune defenses, little is known about its effect on renal function.

This study aims to shed light on kidney involvement in patients with the Omicron variant during the post-acute phase of treatment.

A cohort of 430 Omicron variant patients admitted to Tianjin First Central Hospital in China was analyzed. The patients were selected after completing 7-14 days of acute phase treatment at Tianjin Haihe Hospital. The incidence of kidney involvement was assessed, and the clinical characteristics of the affected patients were examined.

The findings revealed a considerable prevalence of kidney involvement in Omicron variant patients during the post-acute phase. Acute kidney injury (AKI), proteinuria (presence of excess protein in urine), and hematuria (presence of blood in urine) were observed in a significant proportion of cases. The presence of these renal complications has been previously associated with poor clinical outcomes in COVID-19 patients.

Further analysis aimed to identify risk factors associated with kidney involvement in Omicron variant patients. It was found that proteinuria and hematuria in noncritical patients were independent predictors of disease progression, emphasizing the significance of monitoring renal function in all COVID-19 cases. Additionally, AKI was predominantly observed in critical patients, indicating a higher risk of mortality and worse short-term outcomes.

Existing research has demonstrated that severe cases of COVID-19 are often accompanied by kidney-related abnormalities such as acute kidney injury (AKI), hematuria (blood in urine), and proteinuria (excess protein in urine). However, limited data are available on the specific impact of the Omicron variant on renal function.

The study in focus investigated a cohort of patients with the Omicron variant who had completed the acute phase of treatment. Remarkably, none of the patients in the study exhibited AKI or other critical kidney complications.

The cohort primarily consisted of individuals with mild to moderate symptoms, and their hospital stays were relatively shorter compared to patients infected with previous variants.

It is crucial to note that the study focused on the post-acute phase of Omicron variant infection and did not include data from the acute phase. Therefore, the presence of transient renal function changes during the acute phase remains unknown. The absence of AKI during the post-acute rehabilitation phase suggests that kidney dysfunction might be less prevalent in patients with the Omicron variant.

Nevertheless, further investigations are needed to comprehensively understand the temporal dynamics of kidney involvement throughout the course of Omicron variant infection.

While previous studies have emphasized the occurrence of AKI in COVID-19 patients, proteinuria and hematuria have been relatively overlooked. However, these urine abnormalities can also provide valuable insights into the severity and prognosis of the disease. Proteinuria and hematuria have been reported in a significant proportion of COVID-19 patients, with varying prevalence across different studies.

In the context of the Omicron variant, the incidence of hematuria and proteinuria observed in the study was lower compared to previous reports on SARS-CoV-2 and other variants. This suggests that the Omicron variant may cause milder urine abnormalities.

Although proteinuria and hematuria may not be as clinically critical as AKI, their impact on COVID-19 prognosis should not be overlooked. Studies have shown that proteinuria and hematuria can serve as independent predictors of disease severity. The presence of these urine abnormalities may increase the risk of long-term renal damage and adverse outcomes.

Therefore, continuous monitoring of albuminuria and hematuria throughout the clinical process of Omicron infection, including follow-up, is recommended.

The study highlighted the importance of early detection and intervention in Omicron variant patients with kidney involvement. Timely recognition of renal complications, particularly AKI, may facilitate prompt management and improve overall patient outcomes.

The Omicron variant of SARS-CoV-2 emerged in late 2021 and quickly spread across the globe. This highly contagious strain possesses the ability to evade immune defenses and exhibits reduced susceptibility to the COVID-19 vaccination.

Despite these concerning characteristics, Omicron-infected patients generally experienced milder symptoms and required less oxygen support compared to individuals infected with previous variants.


Although the specific impact of the Omicron variant on renal function requires further investigation, the available data suggest that kidney involvement may be less prevalent in patients with this variant. Proteinuria and hematuria, although milder in incidence compared to previous variants, should still be monitored as they can serve as predictors of disease severity and long-term renal outcomes.

Risk factors such as older age, hypertension, higher CRP levels, and increased BMI have been associated with kidney involvement in Omicron variant patients. Overall, a comprehensive understanding of kidney complications in Omicron variant infection is essential for timely detection, intervention, and improved patient outcomes.

Further research is warranted to elucidate the intricate relationship between the Omicron variant and renal function, allowing for the development of appropriate management strategies.

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