About Acute Kidney Injury

Overview

Acute Kidney Injury (AKI) is a sudden drop in how well the kidneys work. This condition used to be called "acute kidney failure." AKI usually happens over a short time, from a few hours to a few days, and it can often be treated so that the kidneys return to normal function. It doesn't happen because of a physical injury to the kidneys, but rather due to issues in the tiny structures inside the kidneys, like blood vessels. Doctors use something called the KDIGO classification (Kidney Disease Improving Global Outcomes) to diagnose AKI. This classification looks at certain signs in the body. These include:

• A rise in blood creatinine levels by at least 0.3 milligrams per deciliter within 48 hours.
• An increase in blood creatinine to 1.5 times the usual level within the past 7 days.
• Producing less than 0.5 milliliters of urine per kilogram of body weight each hour for 6 hours.

When AKI happens, waste products can build up in the blood, and the kidneys can struggle to keep the body’s fluid levels balanced. Fast treatment is critical to avoid lasting kidney damage, and treating AKI early can often bring kidney function back to normal or close to normal.

Causes and Risk Factors

Acute Kidney Injury (AKI) can happen for several reasons, including:

• Reduced blood flow to the kidneys from things like dehydration, low blood pressure, or heart failure.
• Direct kidney damage due to infections, certain medications, or toxins.
• Blocked urine flow, like from kidney stones or an enlarged prostate.

Some factors that raise the risk of AKI can't be changed, called non-modifiable risk factors:

• Age: Older adults are more likely to develop AKI.
• Diabetes: People with diabetes have a higher risk of AKI.
• High blood pressure: This is a major risk factor for AKI.

Other factors can be managed or adjusted, called modifiable risk factors:

• Medications: Some drugs, such as NSAIDs (like ibuprofen) and certain antibiotics, can increase AKI risk. Always follow medication instructions and talk to a healthcare provider if you're unsure.
• Dehydration: Not drinking enough water or losing too much fluid can lead to AKI. It’s important to stay hydrated, especially if you're sick or very active.
• Infections: Infections in the urinary tract or bloodstream can cause AKI. Practicing good hygiene and getting prompt treatment for infections can help lower the risk.

Risk factors can vary for each person, so it’s always best to talk with a healthcare provider for advice specific to you.

Symptoms

The most common early symptoms of AKI may include:

• Swollen face
• Swollen hands or feet
• Foamy urine
• More frequent urination
• Fatigue
• High blood pressure
• High cholesterol
• Breathing difficulties

As AKI progresses or reaches a higher severity, additional symptoms may occur, such as:

• Confusion
• Decreased urine output
• Difficulty concentrating
• Itching
• Muscle twitches and cramping
• Metallic taste in the mouth
• Nausea and vomiting
• Loss of appetite
• Seizures
• Swelling in the body (edema), starting in the ankles and legs (peripheral edema)
• Shortness of breath due to fluid buildup in the lungs

It's important to note that symptoms can vary between individuals and may not always be present. If you experience any of these symptoms or suspect AKI, it's crucial to seek medical attention for proper diagnosis and management.

Diagnosis

To diagnose AKI, healthcare professionals commonly perform the following examinations, tests, and procedures:

• Measuring urine output: Doctors measure how much urine a person produces in a day, which helps them see how well the kidneys are working.
• Urine tests: These tests check for protein in the urine, which can be a sign of kidney damage.
• eGFR test: This blood test estimates the glomerular filtration rate (eGFR), which shows how well the kidneys are filtering waste. It helps determine how severe the AKI is.
• Blood tests: These tests look at levels of creatinine (a waste product that shows kidney function), as well as phosphorus and potassium, which can be affected by AKI.
• Imaging tests: Ultrasounds are used to find any blockages or other issues in the kidneys that might be causing AKI.

To figure out the stage or severity of AKI, doctors may also consider:

• Clinical criteria: The RIFLE and AKIN criteria are systems doctors use to stage AKI by looking at creatinine levels and urine output over time.
• Biomarkers: Substances like Cystatin C and neutrophil gelatinase-associated lipocalin are newer indicators that can help assess how serious the AKI is and predict possible outcomes.

Seeing a healthcare provider is essential for a correct diagnosis and understanding of AKI. They will decide which tests and procedures are needed based on each person’s situation.

Treatment Options

The goals of treatment for AKI are to restore normal kidney function, manage symptoms, and prevent complications. Here are the different types of treatments and how they work to achieve these goals:

• Medications: Medications prescribed for AKI aim to control blood glucose, lower blood pressure, and lower cholesterol levels. These medications help manage the root causes of AKI and prevent further kidney damage.
• Therapies: Therapies like continuous veno-venous hemofiltration (CVVH) and goal-directed therapy (GDT) can help clean the blood by removing waste, inflammatory chemicals, and broken-down blood cells. These treatments support the immune system to work better and help the kidneys recover and function more normally.
• Therapeutic procedures: In severe cases of AKI, renal replacement therapy (RRT) may be needed. This includes treatments like continuous hemodiafiltration and intermittent hemodialysis (IHD). RRT helps fix imbalances in the body's metabolism, electrolytes (minerals that affect heart and muscle function), and acid levels. It also helps control fluid levels and gives the kidneys time to heal.
• Lifestyle changes: Making lifestyle modifications can also play a role in AKI treatment. Quitting smoking, reducing salt intake, limiting alcohol consumption, eating a healthy diet, and engaging in regular physical exercise can help improve symptoms and prevent the condition from becoming severe.

It's important to note that treatment plans may vary depending on the severity and underlying causes of AKI. Always consult with a healthcare professional for personalized advice. Medication dosing may be affected by many factors. Check with your health care professional about dosing for your individual situation. Other side effects can occur. Check with your health care professional or read the information provided with your medication for additional side effect information.