Acute kidney injury

Also called AKI, Acute renal failure

Kidneys failing over hours or days, usually because of dehydration, infection or medication. Often preventable, and the prevention is water and stopping tablets.

What it is

A sudden fall in kidney function, over hours to days. It is common, it affects around one in five emergency hospital admissions, and a significant proportion of it is avoidable.

The causes are usually mundane rather than exotic: not enough fluid reaching the kidneys, from dehydration, diarrhoea and vomiting, bleeding, sepsis or heart failure; a blockage to the flow of urine, often an enlarged prostate; and medicines.

Medicines deserve their own sentence because this is where families and care staff can genuinely prevent harm. Anti-inflammatory painkillers, ACE inhibitors and ARBs for blood pressure, and diuretics are all fine day to day and all dangerous in someone who has stopped drinking or has a vomiting illness. The rule of thumb taught to clinicians is to hold them during acute illness, and it is rarely explained to anybody at home.

Older people, people with chronic kidney disease, diabetes or heart failure, and anybody frail are most at risk.

Most people recover, but AKI leaves lasting damage: it raises the future risk of chronic kidney disease substantially, so it deserves follow-up rather than being treated as an episode that ended.

Signs you might notice

Passing much less urine than usual, or none.

Nausea, vomiting, loss of appetite.

Tiredness, drowsiness, confusion. In an older person new delirium may be the first sign.

Swelling of the ankles, legs or around the eyes.

Breathlessness.

Often it is silent and only shows on a blood test, which is why it is looked for during any acute illness.

Same-day assessment: passing little or no urine, vomiting and unable to keep fluids down, new confusion, or becoming rapidly less well during any illness.

999: severe breathlessness, chest pain, drowsiness, or a seizure.

How it can affect day-to-day life

The classic sequence in a care setting is a chest or urine infection, then reduced drinking, then a fall, then AKI, with each step recorded separately and nobody joining them up. Fluid charts exist for exactly this and are notoriously badly kept.

Somebody with dementia or dysphagia can become dehydrated in a day and cannot say so. Hot weather does the same thing quietly.

The word injury frightens families, who hear permanent damage. Most recovers, and saying so helps, alongside the honest point that it raises future risk.

Discharge is where this falls down. Medicines held in hospital should be restarted deliberately, with a plan and a blood test, and are frequently either never restarted or restarted with no check.

Supporting someone well

Keep fluids going during any illness. This is the single most effective prevention.

Learn the sick day rules for medicines. When somebody has vomiting, diarrhoea, fever or sweats and is not drinking, several common tablets should usually be paused. Ask the GP or pharmacist to write down which ones for this person, before it happens.

Do not give anti-inflammatory painkillers such as ibuprofen to an unwell, dehydrated or older person without checking.

Watch urine output. Fewer or lighter wet pads, or a much drier day than usual, is information.

Treat infection promptly and think of AKI whenever somebody becomes confused during an illness.

At discharge, ask which medicines were stopped, when they restart, and when the next blood test is.

Ask for a kidney function check some weeks after recovery, and for AKI to be recorded on the GP record.

Where to get help

A GP practice or NHS 111 the same day for reduced urine, vomiting or new confusion during illness.

999 for severe breathlessness, drowsiness or seizure.

Kidney Care UK run a helpline and have clear information on sick day rules.

Kidney Research UK for background on kidney disease.