Sepsis-associated acute kidney injury

In sepsis the immune system overreacts, and blood vessels widen and become leaky. Blood pressure falls, so less blood reaches organs including the kidneys. Inflammation and tiny clots in small vessels, together with direct injury to the tubular cells that do the filtering, can reduce the kidney's ability to clear waste and balance fluids and salts. Medicines needed for the infection, such as some antibiotics, and contrast dye used for urgent scans, can add further strain, which is why doses and combinations are reviewed daily in hospital.

Sepsis-associated acute kidney injury is common among patients with severe infection. It is not simply caused by low blood pressure: some people develop kidney injury even when their circulation looks adequate, which is one reason research continues into better ways to detect and prevent it.

The NHS lists high-risk features of sepsis in adults including confusion or slurred speech, uncontrollable shivering or muscle pain, breathing difficulty and changes in skin colour, and in children very fast breathing, fits, a non-blanching rash and extreme sleepiness. The UK Sepsis Trust adds that passing no urine in 24 hours, or in children under 5 none in 12 hours, is a warning sign. Early kidney injury is silent; it is found through blood tests, so people with a suspected serious infection will have creatinine, urea, potassium and lactate checked.

• Call 999 or go to A&E if you or someone you care for shows possible signs of sepsis.

• Do not wait for a rash or a high temperature; older people and those with weak immunity may have a low temperature.

• Tell staff about any kidney disease, regular medicines and recent catheter or surgery.

The priority is rapid antibiotics and finding and removing the source of infection, such as draining an abscess or relieving an obstructed kidney. Intravenous fluids and, if blood pressure stays low, medicines that tighten blood vessels support the circulation; the NHS describes oxygen and specialist monitoring units for severe cases. Doctors avoid medicines that stress the kidneys where possible, adjust antibiotic doses to kidney function and monitor urine output, sometimes through a urinary catheter.

Dialysis, also called renal replacement therapy, is used when potassium or acid levels become dangerous, fluid cannot be cleared or toxins build up. In intensive care it is usually a slow continuous form of treatment, designed to be gentle on an unstable circulation. Most people who need it for sepsis come off it as the kidneys recover, though a minority remain dialysis-dependent.

The NHS notes that many people with acute kidney injury recover fully within a few weeks, but severe cases may take months and some go on to chronic kidney disease. After sepsis, survivors can also have post-sepsis syndrome, which the NHS describes as lasting fatigue, cognitive difficulties or organ complications. Before discharge, the hospital should tell you that you had acute kidney injury, so that it is recorded in your GP notes.

A repeat kidney blood test and urine test, usually within about three months, shows whether function has returned to baseline. If it has not, you may be offered monitoring or a referral for chronic kidney disease. It is common advice to avoid anti-inflammatory painkillers where possible and to follow sick-day guidance during future illnesses.

Prompt treatment of urinary and chest infections, staying hydrated during illness, vaccinations offered by the NHS, good control of diabetes and blood pressure and careful use of catheters all reduce the chance of severe infection. Carry a list of your medicines and make sure anyone assessing you knows you have had kidney injury. If you feel much worse quickly, treat it as urgent rather than waiting for a routine appointment.