Kidney failure is a disease affecting the kidneys, which compromises their functionality.
The main function of the kidneys is to filter the blood and promote the expulsion of excess fluids and metabolic waste products through urine.
When both kidneys fail, we speak of renal failure, which can vary in severity: mild, moderate, or severe. This leads to the accumulation of harmful substances and fluids that disrupt the body’s homeostasis/balance. When the kidneys aren’t working properly, the accumulation of waste products in the blood and fluid imbalances affect the entire body.
A distinction is made between acute renal failure , which is almost always reversible – when the loss of kidney function occurs rapidly (days or weeks), and chronic renal failure, which progresses more slowly (months and years) and causes permanent damage (chronic).
What are the symptoms of acute kidney failure and what are its causes? We discuss this with Dr. Adriana Aroldi , nephrologist at Humanitas Medical Care .
What is acute kidney failure?
Acute kidney failure occurs when the kidneys suddenly stop working properly , within hours or a few days.
The kidneys are responsible for maintaining fluid balance, regulating electrolyte levels, and removing waste products through urine production. When this function fails, toxins accumulate in the blood and damage organs and tissues. Acute kidney failure differs from chronic kidney failure in its rapid onset and the possibility, in many, but not all, cases, of complete recovery of kidney function.
What types of acute kidney failure are there?
The causes of acute kidney failure are classified into three main categories:
Pre-renal causes , the most common, are those due to a reduction in blood flow to the kidneys:
- fluid loss, the most common: severe bleeding, prolonged vomiting , massive diarrhea , persistent hyperglycemia, extensive burns, prolonged high fever without adequate hydration;
- reduction in cardiac output: heart failure/insufficiency, heart attack;
- causes related to an alteration of renal perfusion: liver failure with ascites, anaphylactic shock, sepsis;
- taking certain drugs/substances that can become nephrotoxic: NSAIDs, other drugs if used incorrectly, such as iodinated contrast media (especially in patients at risk or in the presence of other predisposing conditions), some antibiotics, lithium, venoms (that of some vipers, others such as methanol, ethylene glycol), some mushrooms (such as Amanita phalloides) and finally substances such as heroin, cocaine, amphetamines.
Renal causes , which cause direct damage to the kidneys. Examples include:
- pyelonephritis (kidney inflammation/infection)
- primary glomerulonephritis (Berger, membranous, membranoproliferative)
- systemic diseases that also affect the kidneys and cause glomerulonephritis (systemic lupus erythematosus, vasculitis, scleroderma, rheumatoid arthritis , Sjögren’s and Goodpasture’s syndrome, cryoglobulinemia, Henoch-Schönlein purpura, hemolytic-uremic syndrome, multiple myeloma)
- severe infections
- significant cholesterol deposits in the renal arteries with reduced blood flow in the arteries themselves.
Post-renal causes , the least frequent, which determine an impediment to the physiological urinary flow:
- some tumors located in the pelvis (prostate, uterus, lymph node metastases)
- kidney stones obstructing both ureters
- some neurological disorders (neurological bladder, multiple sclerosis and advanced Parkinson’s disease).
Kidney failure: symptoms
Symptoms of acute kidney failure appear rapidly due to the accumulation of fluids, electrolytes, and waste products in the blood, but in some cases the disease may be asymptomatic in the early stages.
Symptoms include:
Urinary symptoms
- decrease in urine production
- presence of blood in the urine or red or brown urine.
Accumulation of fluids
- swelling (edema), especially in the feet and legs, weight gain, eyelid edema (swollen eyes)
- hypertension.
Accumulation of toxins
- nausea, loss of appetite, vomiting, “urine” breath
- shortness of breath, tiredness , daytime sleepiness, up to a state of confusion
- itching, dry skin
- chest pain, tightness in the chest.
Related Disorders
- high potassium: tingling, muscle weakness, cardiac arrhythmias
- low calcium: cramps to the point of tetany.
Acute renal failure: diagnostic tests
The diagnosis of acute renal failure is made with a blood test that measures:
- Creatinine and urea: assess renal function impairment
- Uric acid: high levels may be a sign of kidney failure
- electrolytes such as potassium, calcium, sodium
- urine test: to evaluate the presence of blood or proteins.
Following the diagnosis of acute renal failure, the nephrologist must begin further investigations to evaluate the condition of the kidneys and urinary tract, such as ultrasound, CT scan , MRI and possible renal biopsy if a primary disease affecting only the kidneys is suspected.
How to treat acute kidney failure?
Treatment of acute kidney injury varies depending on the underlying cause and severity of the impairment . The primary goal is to correct the underlying factor that triggered the renal dysfunction and restore fluid and electrolyte balance. In cases of dehydration, intravenous fluid administration can restore renal perfusion. In the presence of electrolyte imbalances, careful monitoring and possible pharmacological intervention are necessary.
Treatment may require discontinuing medications that are potentially toxic to the kidneys or using specific therapies for urinary infections or obstructions. In more severe cases , especially when complications such as fluid retention, significant electrolyte abnormalities, or waste accumulation uncontrollable with medical therapy, temporary dialysis may be necessary to remove accumulated waste and support kidney function until urine output resumes.
Complete recovery is possible, especially if diagnosis is rapid and treatment is started immediately. Follow -up care will allow for monitoring the progression and preventing or early identifying any long-term complications.
