Hospitalized patients especially in the ICU or post-operative and older adults are most susceptible to acute kidney injury (AKI), which develops within a few hours or a few days.
Most AKI cases are reversible. However, it’s important to treat AKI as early as possible to avoid its progression to chronic kidney disease or kidney failure.
What is AKI?
AKI is a sudden, reversible decline in the kidney’s glomerular filtration rate (GFR); in other words, its ability to filter metabolic waste. This kidney damage causes an elevation of serum urea and creatinine, which affects the body’s ability to function properly.
What causes AKI?
AKI causes can be divided into three categories:
Prerenal AKI: Prerenal conditions typically don’t cause permanent damage unless hypoperfusion (decreased blood flow through the kidneys) is severe enough to cause tubular ischemia. Hypoperfusion leads to increased reabsorption of sodium and water, which then leads to low urine output with high urine osmolality and low urine sodium.
Prerenal AKI causes include:
- Low blood pressure or shock.
- Low blood volume after severe bleeding, severe diarrhea or excessive vomiting.
- Heart failure.
- Liver failure.
- Analgesic (acetaminophen, aspirin, codeine) and NSAID (ibuprofen, ketoprofen, naproxen) overuse, which is known to cause analgesic nephropathy.
- Severe allergic reactions.
- Post-major surgeries.
Renal AKI involves kidney disease or direct kidney damage. Common causes include:
- Multiple Myeloma.
- Interstitial nephritis, a condition caused by medication reaction, kidney infections and certain immune disorders.
- A group of diseases called scleroderma that affect the connective tissue that supports internal organs.
- Conditions that cause inflammation or damage to the kidney tubules, to the small blood vessels in the kidneys, or to the filtering units in the kidneys. Examples include tubular necrosis, glomerulonephritis, vasculitis or thrombotic microangiopathy.
Renal AKI is an obstruction in the voiding and collecting parts of the urinary system. Obstruction may also occur at the microscopic level. Causes include:
- Bilateral kidney stone.
- Enlarged prostate.
- Cervical cancer.
- Blood clots in the urinary tract.
- Nervous system conditions that affect the bladder and urination.
What are the symptoms of AKI?
AKI Symptoms differ depending on the cause. Predominant symptoms relate to the underlying cause or the surgical complication that affects the kidneys. General symptoms include:
- Oliguria: Decreased urine output.
- Shortness of breath.
- Swelling in the ankles, legs and around the eyes.
- Chest pain or pressure.
- Seizures or coma in severe cases.
How do doctors diagnose AKI?
A doctor will run different tests depending on the cause. A few of these include:
- Review of prescription and over-the-counter drug use and exposure to iodinated IV contrast.
- Blood tests: complete blood picture, serum creatinine, urea nitrogen, phosphorus and potassium.
- Urinary sediment.
- Urinary diagnostic indices.
- Urinalysis and assessment of urine protein.
- Postvoid residual bladder volume if postrenal cause suspected.
- eGFR (estimated glomerular filtration rate) to estimate the decrease in kidney function.
- Ultrasound or CT imaging.
- Kidney biopsy.
Acute kidney injury is suspected when urine output falls or serum BUN and creatinine levels rise.
Is AKI a rare disease?
AKI stems from other conditions, diseases or infections. Rare kidney diseases such as C3G and FSGS progress straight to end-stage renal disease if left untreated. There’s little chance of an AKI diagnosis in these cases.
In my next article, I’ll discuss treatment options and AKI clinical trials in details.
In the meantime, if you have a nephrology study that needs managed or rescued, speak with one of Biorasi’s medical experts: 786-388-0700 or email@example.com.