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Most patients with COVID-19 have mild symptoms, but about 5% develop severe symptoms, which can include acute respiratory distress syndrome, septic shock, and multiple organ failure. Among the main organs that can become injured or fail, the kidneys have proved to be commonly impacted.


Kidney involvement in COVID-19 is frequent, and up to half of all hospitalized COVID-19 patients develop acute kidney injury (AKI). AKI is a sudden episode of kidney failure or kidney damage that happens within a few hours or a few days. Clinical presentation of kidney involvement from COVID-19 can range from mild proteinuria to progressive AKI, requiring renal replacement therapy (RRT). Proteinuria is a condition that results from too much protein being present in urine—a sign of kidney damage. RRT replaces kidney function and includes multiple kinds of dialysis.

A recent study found that of 3,993 hospitalized patients with COVID-19 , AKI occurred in 1,835 (46%) patients. Among patients with AKI, 19% required dialysis, and half of them died in the hospital. By the time of discharge , only 30% of patients survived with recovery of kidney function. Healthcare facilities may not be prepared for the increased workload to treat survivors of COVID-19-associated AKI who do not fully recover their kidney function. Authors of the article hope that these findings may help these facilities with resource planning.

Additional studies have reported similar findings and conclusions. A Lancet article found that kidney involvement is frequent in COVID-19, with greater than 40% of cases having abnormal proteinuria at hospital admission. The article suggested that AKI affects approximately 20–40% of COVID-19 patients admitted to intensive care in Europe and the USA. It also concluded that AKI “is considered a marker of disease severity and a negative prognostic factor for survival.”

Researchers have not identified a single, exact cause of AKI in patients with COVID-19. Writing in the Lancet, researchers state that, “The cause of kidney involvement in COVID-19 is likely to be multifactorial, with cardiovascular comorbidity and predisposing factors (e.g., sepsis, hypovolemia, and nephrotoxins) as important contributors.” Cardiorenal syndrome, which includes a range of disorders of the heart or kidney where dysfunction in one organ may induce dysfunction in the other, could impact the relationship between COVID-19 and AKI. However, it is still just one factor among many that may cause AKI in COVID-19 patients.

Because no specific treatment options exist for AKI secondary to COVID-19, intensive care is primarily supportive. Current approaches for the prevention and management of AKI are based mainly on clinical experience. AKI treatment strategies are being adapted empirically to treat COVID-19 patients who present the signs and symptoms of kidney damage.

Among patients hospitalized with COVID-19, AKI is common and is associated with high mortality. Because of the significant likelihood of the development of AKI in patients with severe COVID-19 and limited prospects for full recovery, further research is needed to improve the understanding of AKI secondary to COVID-19. A better understanding may allow us to predict the risk of AKI, identify the exact mechanisms of renal injury in COVID-19 patients, and suggest targeted interventions.


Opinions expressed in this article are not necessarily those of bioMérieux.


  • Acute Care