Understanding and Causes of Acute Kidney Injury (AKI)

The knowledge and understanding and causes of acute kidney injury has evolved over the years. Its names and definitions changed as knowledge and understanding of the disease continued growing. Acute Kidney Injury (AKI), which is the term that has replaced the name acute renal failure (ARF), is a common problem among hospitalized patients. It is particularly greater among the elderly population whose numbers are increasing as people live longer.

World Health Organization (WHO) on The Global Burden of Kidney Disease and The Sustainable Development Goals, stated that Kidney disease has an indirect impact on global morbidity and mortality by increasing the risks associated with at least 5 major killers. They are:

To better understand acute kidney injury, here’s a little information on the anatomy and physiology of the human Kidney.

Brief Anatomy and Physiology of the Kidney

The Kidneys are also called renes, which is a Latin word from which we have the derivative renal. The kidneys are a pair of bean-shaped organs whose function is for excretion. They are situated on the posterior abdominal wall, one on each side of the vertebral column. The kidneys are well positioned in the lumbar region of the abdomen at the level of the 12th thoracic vertebrae extending to the level of the 3rd lumbar vertebrae. This is why the disease is associated with pain on the back.

Your kidneys are overly popular for one important function; which is getting rid of body waste through urine that are either ingested or produced by the body. But the Kidney has a wide array of functions it plays for the body. Another vital function of the kidney is its ability to control the volume and electrolyte composition of the body’s fluids. This regulatory function of the Kidney lets it maintain a stable internal environment in the body which is necessary for variety of cells to perform various activities. The Kidney does this by filtering the blood.

A few functions of the Kidney are listed below:

  • Removal of metabolic waste products and foreign chemicals from the body.
  • Regulation of water and electrolytes (sodium, potassium, calcium, hydrogen, calcium, magnesium and phosphate ions) balances in the body.
  • Regulate arterial pressure of the body.
  • Regulation of acid-base balance in the body.
  • Regulate red blood cells production in the body especially in times of great need.
  • Secretion, metabolism and excretion of hormones.
  • Glucose production which is used as energy by the body, from non-carbohydrate sources (gluconeogenesis).

So then, What is Acute Kidney Injury?

Acute kidney injury (AKI) is when there is impairment of kidney filtration and excretory functions over days to weeks. This often results in the retention of nitrogenous and other waste products in the body which would have normally been cleared out by the kidneys through urine. Doctors actually describe acute kidney injury as a syndrome. That means, it is not a single disease, but rather a group of conditions that share common diagnostic features.


Doctors have traditionally divided AKI into three broad types:

  1. Prerenal azotemia (from azo meaning nitrogen and -emia meaning in the blood): it is the most common form of AKI. This type refers to a rise in the levels of creatinine and Blood Urea Nitrogen (BUN) due to a decrease in blood circulation to the Kidneys.
  2. The Intrinsic acute kidney injury: Intrinsic renal diseases that result in acute kidney injury can be due to injury at certain sites: Kidney tubules, interstitium, the vessels that supply the Kidney or glomerulus (a part of the kidney).
  3. Postrenal acute kidney injury: This occurs when the normally unidirectional flow of urine is acutely blocked either partially or totally. The blockage usually leads to an increase in retrograde pressure, and this interferes with the filtration process of the kidney. 

Causes of Acute Kidney Injury

Doctors categorize the causes of acute kidney injury based on their types. Generally, one can have acute kidney injury if there is:

  • Inadequate renal plasma flow.
  • Decreased cardiac output.
  • When the liquid portion of your blood is too low due to dehydration, vomiting, diarrhea etc.
  • Infections to the Kidney (sepsis).
  • Reduced blood flow and oxygen to the Kidney (ischemia).
  • Toxins which are constantly in circulation and has to be filtered by the Kidney, leaving the Kidney to toxic injury.
  • Many drugs like antibiotics and painkillers are also known to be causes of acute kidney injury.
  • When flow of urine is blocked either partially or totally.

Symptoms of Acute Kidney Injury

Although AKI is often asymptomatic (showing no symptoms), sometimes it might show subtle symptoms. Your doctor can accidentally identify AKI at the hospital when you’re there for a different purpose.

Some of the symptoms include:

If you experience any of these symptoms, seek your physician immediately for proper assessment and diagnosis. Your doctor will ask you to do several tests and scans to check your kidney health and function. The doctor will also conduct a Giordano’s test to check for pain in the back. Your doctor can carry out this diagnostic test for AKI in his consulting room.

What Are The Complications?

Complications of acute kidney injury depends on the severity of the disease. These complications are:

  • Buildup of nitrogenous waste products.
  • Expansion of extracellular fluid volume.
  • Low blood level of sodium electrolyte (hyponatremia).
  • High level of electrolyte potassium in the blood (hyperkalemia).
  • Buildup of acid in the blood due to bad regulation of acid-base balance.
  • Infections.
  • Heart dysfunctions.
  • Reduced red blood cell
  • And bleeding.

Acute Kidney Injury Treatment and Prevention

Acute kidney injury is not a self-treatable disease and one should always consult a physician when they have symptoms. AKI significantly increases the risk of in-hospital and long term mortality. However, patients with AKI can recover even after severe dialysis; and return to normal or nearly normal Kidney function. Don’t forget to always consult your physician if you are experiencing any of the above symptoms.

As scary as it is, AKI can be treated when you visit the hospital. It has a wide range of treatment which include:

  • Replacement of fluids lost.
  • Drugs as prescribed by the physician.
  • Dialysis (which balances your body fluids by removing excess water, electrolytes and toxins) is indicated when medical management fails. Hemodialysis is a type of dialysis.

In order to prevent acute kidney injury, take the following steps:


  • Clinically Oriented Anatomy, keith moore
  • B.D. Chaurasia’s Human Anatomy volume 2, B.D. chaurasia
  • Guyton and Hall textbook of Medical Physiology thirteenth edition, John E. Hall
  • The New England Journal of Medicine, Acute renal failure, Ravi Thadhani M.D., Manuel Pascual M.D., Joseph V. Boneventre M.D., PH.D.
  • Harrison’s Principles of Internal Medicine, by Jameson, Fauci, Kasper, Hauser, Longo, Loscalzo.
  • NCBI – Acute Kidney Injury 

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