Sepsis is a life-threatening medical emergency that occurs when the body’s response to an infection becomes dysregulated, leading to widespread inflammation. This uncontrolled immune reaction can cause damage to various organs throughout the body. A common complication of sepsis is acute kidney injury (AKI), which can progress to kidney failure. Sepsis is a leading cause of AKI, accounting for an estimated 32% to 48% of cases.
The Body’s Systemic Response to Sepsis
During sepsis, the body’s immune system, as it fights infection, releases a flood of inflammatory chemicals into the bloodstream. These chemicals, known as cytokines, normally help fight infection, but their excessive release can have harmful widespread effects. This systemic inflammatory response can cause blood vessels to widen and become leaky, leading to a drop in blood pressure.
This widespread inflammation and low blood pressure can reduce blood flow to various organs, including the kidneys. When organs do not receive enough blood, they are deprived of the oxygen and nutrients needed to function properly. This can initiate organ dysfunction, with the kidneys often being among the first organs affected.
How Sepsis Directly Damages Kidneys
Sepsis directly harms the kidneys through several complex mechanisms, extending beyond low blood pressure. Low blood pressure, known as hypoperfusion, reduces blood flow to the kidneys, depriving them of oxygen and nutrients. This can injure kidney cells, particularly in the tubules, which filter waste.
Beyond hypoperfusion, systemic inflammation can directly injure kidney cells. Inflammatory mediators and oxidative stress can damage delicate structures within the kidneys. Sepsis can also activate the coagulation cascade, leading to tiny blood clots within the small blood vessels of the kidneys, a condition called disseminated intravascular coagulation (DIC). These micro-clots further impede blood flow and oxygen delivery, contributing to kidney damage and dysfunction.
Recognizing Kidney Damage During Sepsis
When sepsis affects the kidneys, several signs and symptoms may become apparent. A decrease in urine output (oliguria), or even a complete lack of urine production (anuria), can indicate impaired kidney function. Fluid retention may also occur, leading to swelling (edema) in areas such as the legs, ankles, or around the eyes.
The accumulation of waste products in the blood can affect the brain, leading to changes in mental status like confusion or drowsiness. To confirm kidney damage, healthcare providers rely on diagnostic tests. Elevated levels of blood creatinine (a muscle waste product) and blood urea nitrogen (BUN), indicating urea buildup, are indicators of impaired kidney filtration.
Medical Interventions for Sepsis-Related Kidney Issues
Treating sepsis and its impact on the kidneys requires immediate medical intervention, often in an intensive care unit. A primary step involves administering broad-spectrum antibiotics promptly to combat the infection. Delaying antibiotic treatment can worsen outcomes, with each hour of delay potentially increasing the risk of death in patients with sepsis and acute kidney failure.
Intravenous fluids help maintain adequate blood pressure and ensure sufficient blood flow to organs. If fluids alone are not enough to stabilize blood pressure, vasopressors may be used to constrict blood vessels and raise blood pressure. When kidney function is compromised and waste products accumulate, dialysis (hemodialysis or peritoneal dialysis) may be initiated. This artificial filtration temporarily removes waste and excess fluid from the blood, supporting the body while medical teams address the underlying sepsis and work towards kidney recovery.
Long-Term Kidney Health After Sepsis
The long-term impact of sepsis on kidney health varies. Some people who experience sepsis-induced acute kidney injury may achieve full recovery of their kidney function. However, many survivors do not return to their baseline kidney function by the time they are discharged from the hospital.
For others, kidney damage can lead to chronic kidney disease (CKD), a long-term condition of declining kidney function. In severe instances, patients may develop end-stage renal disease (ESRD), which necessitates permanent dialysis or a kidney transplant. Regular follow-up and monitoring of kidney function are important to detect and manage ongoing problems.