Acute Kidney Injury – Symptoms and Causes
Overview
Acute kidney injury occurs when the kidneys suddenly lose their ability to filter waste from the blood. This serious condition causes harmful waste buildup and chemical imbalances in the body. The condition was previously known as acute kidney failure.
Hospital patients, particularly those in intensive care units, face the highest risk of developing acute kidney injury. The severity can range from mild to life-threatening, with severe cases potentially becoming fatal if left untreated.
Acute kidney injury can often be reversed. People who are otherwise healthy may regain full or nearly full kidney function with proper treatment. Recovery depends on the underlying cause, severity of the injury, and the person’s overall health status.
Signs You May Notice
People with sudden kidney problems might see several changes in their bodies.
You may urinate less than usual. Your body might hold on to too much fluid, making it hard to breathe or causing swelling in your legs and feet.
You might feel very tired or confused. Some people feel sick to their stomachs or have pain in their abdomen or sides. Weakness is common, and your heart might beat unusually.
Your skin could itch, and you might not feel hungry. Some people have chest pain. In very bad cases, seizures or loss of consciousness can happen.
Sometimes, people with kidney problems don’t notice anything wrong. Doctors might find the problem when doing tests for something else.
When You Should Talk to a Doctor
If you notice any signs of sudden kidney problems, don’t wait. See your doctor right away or go to the emergency room. Getting help quickly can make a big difference in your recovery.
What Causes Acute Kidney Injury
Reduced Kidney Blood Flow
Several conditions can reduce blood flow to the kidneys and trigger acute kidney injury.
Dehydration, which happens when you lose too much body fluid, is a common cause. Serious infections, especially those leading to sepsis, can also restrict blood flow to these vital organs.
Common pain relievers like aspirin, ibuprofen, and naproxen may harm kidney function when taken regularly or in high doses. Significant blood or fluid loss from injuries or surgery can quickly reduce kidney blood flow.
Cardiovascular issues pose significant risks for kidney damage. Heart attacks, heart failure, and other cardiac conditions reduce the blood pumped to the kidneys. Similarly, liver diseases like cirrhosis limit proper blood flow throughout the body, including to the kidneys.
Other causes include:
- Severe allergic reactions (anaphylaxis)
- Extensive burns
- Blood pressure medications causing very low blood pressure
Kidney Tissue Damage
Direct damage to kidney tissue can occur through several mechanisms.
Glomerulonephritis, inflammation of the kidney’s filtering units, can happen suddenly and disrupt normal function.
Medication-related damage is common with:
- Certain antibiotics
- Some chemotherapy drugs
- Contrast dyes used in imaging tests
Toxins that harm kidneys include:
- Alcohol (especially binge drinking)
- Heavy metals
- Recreational drugs like cocaine
Infections can directly damage kidney tissue, including COVID-19 in some cases. Blood conditions that affect kidney vessels, such as blood clots or cholesterol deposits, block normal blood flow and damage tissue.
Other causes of kidney tissue damage include:
- Autoimmune diseases like lupus
- Hemolytic uremic syndrome
- Scleroderma
- Rhabdomyolysis (muscle breakdown releasing harmful proteins)
- Tumor lysis syndrome (when cancer cells break down rapidly)
Urinary Tract Blockages
When urine can’t flow properly from the kidneys, pressure builds up and damages these organs.
Kidney stones are a common cause of blockage, forming when minerals in urine crystallize.
In men, an enlarged prostate often blocks urine flow. Several cancers can obstruct urinary pathways, including:
- Bladder cancer
- Prostate cancer
- Cervical cancer
- Colon cancer that spreads nearby
Blood clots in the urinary tract create sudden blockages. Nerve damage affecting bladder control can prevent normal urine elimination, backing up into the kidneys.
Abnormal growths near the ureters can block urine flow by compressing these tubes that carry urine from the kidneys to the bladder.
Risk Factors
Several factors can raise your chance of developing acute kidney injury.
People with existing kidney disease face a higher risk. Though this condition affects all ages, older adults are more vulnerable.
Being hospitalized for serious illnesses requiring intensive care significantly increases risk. Other medical conditions that make kidney injury more likely include:
- Blood vessel blockages in arms or legs (peripheral artery disease)
- Poorly managed diabetes
- High blood pressure
- Heart failure
- Liver diseases
- Certain types of cancer and cancer treatments
Health issues can impact kidney function by altering blood flow or causing inflammation that harms kidney tissue.
Complications
Acute kidney injury can lead to several serious complications.
Fluid can build up in the lungs, making it difficult to breathe. When the heart’s lining (pericardium) becomes inflamed, patients may experience chest pain.
Muscle weakness commonly occurs when electrolytes and fluids in the blood become unbalanced. This affects muscle function throughout the body.
In severe cases, permanent kidney damage may develop, resulting in end-stage renal disease. People with this condition require ongoing dialysis treatments or a kidney transplant to survive.
The worst complication is death, which can occur if the kidneys fail completely and treatment is not timely or effective.
Common complications include:
- Fluid buildup in lungs
- Chest pain from inflamed heart lining
- Muscle weakness
- Permanent kidney damage
- Life-threatening kidney failure
Prevention
Taking steps to protect your kidneys can lower your risk of acute kidney injury. Here are several approaches to consider:
Address Infections Promptly
Get medical care quickly for serious infections to prevent kidney damage.
Manage Existing Conditions
Work closely with healthcare providers if you have kidney disease, diabetes, or high blood pressure. These conditions increase your risk of kidney injury, so following your treatment plan is essential.
Be Careful with Medications
If you have kidney disease risk factors, ask your healthcare team whether your prescription medications are kidney-safe.
For over-the-counter pain relievers like acetaminophen, ibuprofen, aspirin, and naproxen sodium:
- Always follow dosage instructions
- Avoid exceeding recommended amounts
- Be extra cautious if you have kidney problems, diabetes, or high blood pressure
Adopt Healthy Habits
A kidney-friendly lifestyle includes:
- Regular physical activity
- Balanced, nutritious diet
- Moderate alcohol consumption, if any
These preventive measures can greatly lower your risk of acute kidney injury, especially if you have existing health conditions.
