sudden kidney

Overview

Acute kidney injury (AKI) is a sudden episode of kidney failure or kidney damage that happens within a few hours or days. The kidneys stop filtering waste from the blood properly, which can cause dangerous levels of waste to build up.

AKI is fairly common, especially among people who are already in the hospital or have serious health conditions.

Anyone can get AKI, but it is more common in older adults, people with chronic kidney disease, diabetes, high blood pressure, heart failure, or liver disease. It also affects people who are very dehydrated or have a severe infection.

Symptoms

Common symptoms

• Decreased urine output (less than normal or none at all)
• Swelling in the legs, ankles, or feet (fluid buildup)
• Feeling very tired or weak
• Confusion or trouble thinking clearly
• Nausea and vomiting
• Shortness of breath
• Chest pain or pressure

Symptoms in children

• Less wet diapers than normal (decreased urination)
• Irritability or crying more than usual
• Poor feeding or vomiting
• Swelling in the face, hands, or feet

Symptoms in older adults

• Confusion or drowsiness
• Loss of appetite
• Swelling in the lower legs or feet
• Less frequent urination

Causes

Main causes

• Severe dehydration (losing too much fluid from vomiting, diarrhea, sweating, or not drinking enough)
• Serious infections like sepsis
• Very low blood pressure (shock)
• Certain medications (like some painkillers, blood pressure pills, or antibiotics)
• Blockage in the urinary tract (such as an enlarged prostate, kidney stones, or tumor)
• Damage to the kidney from toxins, contrast dye used in scans, or severe muscle injury

Risk factors

• Age 65 or older
• Chronic kidney disease or diabetes
• High blood pressure or heart failure
• Liver disease or lung disease
• Recent surgery (especially heart surgery)
• Taking medications that affect the kidneys, such as nonsteroidal anti-inflammatory drugs (NSAIDs)

When to see a doctor

See a doctor urgently if:

• Any sudden decrease in how much you urinate
• Severe swelling in your legs or face
• Confusion or trouble breathing
• You feel like you might pass out

Book a routine appointment if:

• If you have risk factors and notice any changes in urination or swelling
• Before starting a new medication that might affect your kidneys
• If you have a chronic condition (like diabetes or high blood pressure) and your urine output has changed slightly

Diagnosis

Doctors diagnose acute kidney injury by reviewing your symptoms, medical history, and running tests to check how well your kidneys are working.

Tests that may be done

• Blood tests to measure creatinine and blood urea nitrogen (BUN) – these show waste buildup
• Urine tests to look for signs of kidney damage or infection
• Kidney ultrasound to check for blockages or structural problems
• Sometimes a kidney biopsy (taking a small sample of kidney tissue) to find the exact cause

What to expect at your appointment

You will likely need to stay in the hospital for monitoring and treatment. Doctors will check your kidney function daily and may adjust your fluids and medicines. The good news is that with prompt care, most people see improvement within days to weeks.

Treatment

Treatment for AKI focuses on fixing the underlying cause and supporting your kidneys while they heal. This is usually done in the hospital, but milder cases may be managed at home.

Self-care at home

• Follow your doctor’s advice about how much fluid to drink – sometimes you need more, sometimes you need less
• Avoid medicines that can harm kidneys, such as ibuprofen, naproxen, or other nonsteroidal anti-inflammatory drugs (NSAIDs) unless your doctor says it is safe
• Eat a low-salt diet to help control swelling and blood pressure
• Stay hydrated if you have been dehydrated, but only as directed by your healthcare team

Medical treatments

Treatment may include intravenous (IV) fluids to correct dehydration, medications to control blood pressure or treat infection, and diuretics (water pills) to remove extra fluid. In severe cases, dialysis (a machine that filters your blood) may be used temporarily until your kidneys recover.

When is surgery considered?

If a blockage in the urinary tract (such as a kidney stone or an enlarged prostate) is causing AKI, you may need a procedure to remove the blockage. This could be done with a stent, a tube inserted through the skin, or surgery to remove the obstruction.

Living with this condition

After AKI, you will need regular follow-up appointments to check your kidney function. Your doctor may recommend a low-salt diet and careful monitoring of your fluid intake. Most people can return to normal activities within a few weeks to months, but it depends on how severe the injury was.

Lifestyle tips

• Drink enough fluids to stay well-hydrated (ask your doctor how much is right for you)
• Avoid taking NSAIDs and other kidney-harming medicines
• Keep your blood pressure and diabetes under control
• Exercise regularly (walking, swimming, or other gentle activities) to support overall health
• Do not smoke – smoking damages blood vessels and can worsen kidney problems

Diet and exercise

Eat a balanced diet that is low in salt and processed foods. Focus on fruits, vegetables, whole grains, and lean proteins. Work with your doctor or a dietitian to get a plan that fits your needs. Gentle exercise like walking or yoga can help you feel better and manage weight, but check with your doctor before starting a new routine.

Mental health and emotional wellbeing

Going through AKI can be stressful and frightening. You may feel anxious about your health or about the future. It is normal to have these feelings. Talk to your doctor or a counsellor if you need support. Many people recover fully and return to a normal quality of life.

Prevention

Many cases of AKI can be prevented by staying well-hydrated, avoiding overuse of NSAIDs, managing chronic conditions like diabetes and high blood pressure, and getting prompt treatment for infections.

Vaccines

Getting recommended vaccines (like the flu vaccine and COVID-19 vaccine) can help prevent infections that might lead to AKI.

Screening programmes

If you have risk factors such as diabetes, high blood pressure, or chronic kidney disease, have your kidney function checked regularly as part of your routine health checks.

Complications

If left untreated

• Permanent kidney damage that may lead to chronic kidney disease or end-stage kidney failure
• High potassium levels (hyperkalemia) that can cause dangerous heart rhythms
• Fluid buildup in the lungs (pulmonary edema) leading to breathing trouble
• Increased risk of heart attack or other heart problems
• Weakened immune system, making you more prone to infections

Long-term outlook

With prompt treatment, the outlook for acute kidney injury is generally good. Most people recover kidney function within days to weeks. Even if you need temporary dialysis, many people get better and can stop it. The key is to get care quickly and follow your healthcare team's advice.

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