Acute Kidney Injury – Causes, Treatment, and Prevention

Overview

Acute Kidney Injury is a condition in which kidney function has failed. The condition can lead to various complications as waste products start building up in the blood, along with excess fluid. As a cascade effect, it leads to damage to the heart, lungs and brain. If left untreated, or in severe cases, Acute Kidney Injury can be fatal. In this article, we will learn about various aspects of the condition.

Introduction

Acute Kidney Injury (AKI), also called Acute Renal Failure (ARF) or Acute Kidney Failure (AKF) is a condition in which the kidney function stops altogether. This situation develops over a few days generally, or in a few hours, in some cases. As a result, waste products which would have otherwise been filtered out by the kidneys now start accumulating in the blood. The fluid and chemical-levels reach abnormal or dangerous levels. In some cases, AKI can be fatal. However, if the person’s general health is good and proper treatment is given on time, AKI can be reversed. The kidney function can be regained partly or completely.

The word injury in AKI can be misleading. It has nothing to do with trauma or physical injury caused by say, a motor-vehicle accident. Here, injury refers to damage caused to nephrons, blood-vessels, glomeruli and other microscopic components of the kidney’s anatomy which achieve the kidney function.

Signs and Symptoms

In very rare cases, AKI does not show any symptoms and it can only be detected after a laboratory examination for some other reason. However, in most people, AKI shows immediate and prominent symptoms that cannot be missed by either patient or the family.

• The first and immediately noticeable change is the decreased urine output, although in some people, urine output remains normal but other symptoms are visible
• Due to electrolyte imbalance, there is fluid retention which causes edema or swelling in the hands, legs, ankles and feet.
• Dyspnoea or shortness of breath due to lungs being affected
• Fatigue and Weakness
• Brain fog or confusion which is a sign that the brain is affected
• Nausea and Vomiting
• Arrhythmias or irregular heartbeat
• Tightness, pain or pressure in the chest which indicates the heart is affected
• Seizure, fainting, or coma in severe cases

Causes

There are 3 categories of causes, depending on how they affect the kidney:

1. There is a condition that slows down blood-flow to the kidneys
2. There is direct damage experienced by the kidneys
3. There is some blockage in the kidneys, because of which urine can’t leave the body properly

1. Conditions that slow down blood-flow to the kidneys

• Severe dehydration
• Liver failure
• Blood-loss or fluid-loss
• BP medication
• Reckless or frequent use of over-the-counter drugs such as aspirin, ibuprofen (Advil, Motrin IB, etc) and naproxen sodium (Aleve, etc)
• Heart disease
• Infections of certain kinds
• Heart attack
• Certain classes of drugs
• Anaphylaxis or severe allergic reactions
• Severe burns

2. Direct damage experienced by the kidneys caused by:

• Cholesterol deposits that block blood-flow in the kidneys, similar to what happens in the heart
• Blood clots in blood-vessels in and around the kidneys
• Glomerulonephritis: Glomeruli are tiny filters in the kidney and these can get inflamed
• Lupus, an autoimmune system disorder that causes glomerulonephritis
• Infections of certain kinds, example – Covid-19 infection
• Haemolytic uremic syndrome, a condition in which red-blood-cells don’t live long and get destroyed prematurely
• Certain medications such as antibiotics, dyes used during imaging tests and chemotherapy drugs
• Scleroderma, an assortment of conditions that affect the connective tissues and skin
• Toxic substances such as industrial-grade alcohol, cocaine that comes from drug abuse and heavy metals used in certain industries
• Thrombotic thrombocytopenic purpura, a rare blood disorder
• Rhabdomyolysis is a condition in which muscle-tissue starts breaking down. This creates toxic wastes that damage the kidney
• Tumour lysis syndrome is a condition in which tumour cells are broken down. This leads to toxic wastes that can damage the kidney

3. Urinary obstructions or urine blockage in the kidneys caused by

• Cancers of the bladder, prostate, colon or cervix
• Kidney stones
• Blood clots that clog up the urinary tract
• Enlarged prostate that puts pressure on the urethra and affects urine flow
• Damage to nerves that control the bladder

Risk Factors

AKI rarely occurs in isolation. It invariably occurs due to one or more pre-existing condition. This means, a perfectly healthy person is at low risk of AKI. Conditions that increase risk are:

• Advanced age, and subsequent decline in organ function
• Being hospitalized for a serious condition, especially staying in the ICU
• Peripheral artery disease (PAD) characterised by blockages in blood-vessels of the arms or legs
• Hypertension or high BP
• Diabetes
• Heart failure
• Diseases of the liver
• Diseases of the kidney
• Some cancers, and the treatment involved

Complications

• Dyspnoea: AKI causes fluid to build-up in the lungs leading to shortness of breath
• Muscle weakness/fatigue: The electrolyte and fluid imbalance in the blood affects muscle tissue leading to pain, weakness and fatigue in the muscles
• Pericarditis: The pericardium is a thin lining that covers the heart. When this gets swollen, inflamed, or irritated, there is a sharp pain in the chest
• Permanent kidney failure: Also called End-stage Renal Failure, in which case, the kidney damage is permanent. The patient will require life-long dialysis or kidney transplantation to survive.
• Death: In some cases, complications arising out of AKI can make it fatal

Diagnosis

• Urine output measurement: The patient’s urine output is measured over a 24-hour timeframe to determine if its normal, or a matter of concern
• Urinalysis: A sample of urine is analysed chemically to look for any markers that indicate AKI
• Blood tests: Urea is a chemical waste product caused by ammonia that is produced by the liver. Creatinine is a waste product produced by the normal wear and tear of muscles. Urea and creatinine are effectively filtered out of the body, by the kidneys through the urine. If their levels in the blood are high, it is an indication of AKI.
• Imaging tests: A CT scan or ultrasound of the kidneys help detect any abnormality in the kidney’s anatomy.
• Biopsy: In some cases, the doctors may recommend taking a tiny sample of kidney tissue and analysing it under the microscope.

Treatment

Treating AKI will require hospitalization. Firstly, the doctors will treat the underlying condition or disease that caused AKI and then address complications arisen out of it. This involves a range of medication and procedures.

• Dialysis: In order to stabilize the condition, the doctors may recommend temporary dialysis. This helps remove the toxins, excess fluids and excess potassium from the blood. Dialysis involves pumping the blood out of the body, filtering it in a machine outside the body and restoring the filtered or cleaned-up blood to the body.
• Fluid balancing: In some cases, the AKI may be caused by low fluid content in the body. In such a case, IV fluids are given. When AKI has been caused by excess fluid, then diuretics are given to expel extra fluids through the urine.
• Balancing potassium levels: Excess potassium in the blood can cause arrhythmias or irregular heartbeat that can get fatal, and/or muscle weakness. If the kidneys are not filtering potassium effectively from the blood, the doctor may prescribe medication containing glucose, calcium or sodium-polystyrene-sulfonate to keep potassium levels in check.
• Balancing calcium levels: If calcium levels in the blood drop (hypocalcemia), there are various consequences such as tingling sensation in the body, muscle aches and muscle spasms. The doctors will administer calcium medication.

Prevention

An occurrence of AKI is hard to predict. The risk factors have already been listed earlier. To reduce the risk further, you can:

• Avoid abuse of OTCs: If and when you have been prescribed over-the-counter drugs for different conditions, pay attention to their labels. Medication such as ibuprofen (Advil, Motrin IB, etc), aspirin, naproxen sodium (Aleve, etc) and acetaminophen (Tylenol, etc) come with clear instructions on safe dosage. Follow this strictly. This is all the more necessary if you have pre-existing conditions such as hypertension, diabetes and kidney disease.
• Manage kidney conditions: If you have pre-existing kidney conditions or kidney disease, you must work closely with your doctor to manage the same, else the risk of AKI will increase. This is all the more necessary if you have other conditions such as hypertension and diabetes.
• Healthy lifestyle: A healthy diet rich in fresh fruits and vegetables, lean meat, whole grains and healthy fats, as well as drinking in moderation or quitting alcohol – go a long way in reducing the risk for AKI.

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Reviewed by Dr Suresh S Venkita, Group Medical Director, Kauvery Hospitals

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NOTE: Take medications only when prescribed by your doctors, self-medication must be avoided under any circumstances.

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Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai, Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.

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