Published: 18 Jun 2025

ICD9: 584.5      ICD10: N17.0      ICD11: GB60.Z

Acute tubular necrosis (ATN), also known as renal tubular necrosis, is a kidney disorder involving damage to the tubular cells of the kidneys.
These cells are crucial for reabsorbing essential substances and excreting waste products from the blood to form urine. When these cells are injured or destroyed, the kidneys can't function properly, leading to a buildup of waste products and imbalances in electrolytes and fluids.

Here's a breakdown:

Acute: Meaning it develops suddenly and rapidly (over hours to days).
Tubular: Referring to the renal tubules, the small tubes in the kidneys responsible for reabsorbing water, electrolytes, and other substances back into the bloodstream and for excreting waste products.
Necrosis: Meaning cell death.

Causes of ATN:

ATN has several potential causes, but the most common are:

1. Ischemia (Lack of Blood Flow):
This is the most frequent cause. It happens when the kidneys don't receive enough blood supply. This can be due to:
Severe dehydration
Shock (septic, hypovolemic, cardiogenic)
Surgery (especially heart surgery)
Blood loss
Blockage of blood vessels supplying the kidneys (renal artery stenosis or thrombosis)

2. Nephrotoxic Substances (Toxins):
Certain substances can directly damage the kidney tubules. These include:
Medications:
* Aminoglycoside antibiotics (e.g., gentamicin, tobramycin)
* Amphotericin B (antifungal)
* Nonsteroidal anti-inflammatory drugs (NSAIDs) in susceptible individuals
* ACE inhibitors and ARBs in certain situations (e.g., with renal artery stenosis)
* Chemotherapy drugs (e.g., cisplatin)
* Radiocontrast dyes (used in imaging procedures)
Poisons:
* Heavy metals (e.g., mercury, lead)
* Ethylene glycol (antifreeze)
* Certain plant toxins

3. Sepsis:
Severe infection leading to systemic inflammation.

4. Rhabdomyolysis:
Breakdown of muscle tissue releases myoglobin, which can damage the kidneys.

5. Tumor Lysis Syndrome:
The breakdown of cancer cells releases intracellular contents, which can overwhelm the kidneys.

Symptoms of ATN:

The symptoms of ATN vary depending on the severity of the condition, but may include:

Decreased urine output (oliguria) or no urine output (anuria): This is a hallmark symptom.
Fluid retention: Leading to swelling (edema) in the legs, ankles, or feet.
Elevated blood pressure: Due to fluid overload.
Fatigue and weakness: From the buildup of waste products.
Nausea and vomiting: Also from waste buildup.
Confusion or altered mental status: In severe cases.
Electrolyte imbalances: Such as high potassium (hyperkalemia) or low sodium (hyponatremia), which can cause heart problems or seizures.
Shortness of breath: Due to fluid in the lungs (pulmonary edema).
Dark urine: If caused by rhabdomyolysis.

Diagnosis of ATN:

Diagnosis typically involves:

Medical history and physical exam: To identify risk factors and symptoms.
Blood tests: To assess kidney function (BUN, creatinine), electrolyte levels, and complete blood count.
Urine tests: To analyze urine volume, specific gravity, and presence of protein, blood, or cellular casts (evidence of tubular damage). Fractional excretion of sodium (FENa) is often helpful.
Kidney ultrasound: To rule out obstruction of the urinary tract.
Kidney biopsy: In some cases, to confirm the diagnosis and determine the cause.

Treatment of ATN:

Treatment focuses on:

Addressing the underlying cause: Treating sepsis, stopping nephrotoxic medications, restoring blood flow.
Supportive care:
Fluid management: Careful monitoring of fluid intake and output to prevent fluid overload or dehydration.
Electrolyte balance: Managing electrolyte imbalances with medications or dialysis. Hyperkalemia is a critical concern.
Dialysis: If kidney function is severely impaired, dialysis may be needed to remove waste products and excess fluid from the blood.
Nutritional support: Providing adequate nutrition.

Prognosis of ATN:

The prognosis of ATN depends on the underlying cause, the severity of kidney damage, and the patient's overall health.

Recovery is possible: With prompt and appropriate treatment, kidney function can often recover, although it may take weeks or months.
Chronic kidney disease (CKD): In some cases, ATN can lead to permanent kidney damage and CKD.
Death: Severe ATN can be life-threatening, especially in critically ill patients.

In Summary:

Acute tubular necrosis is a serious condition where the kidney's filtering units are damaged. Early diagnosis and treatment are crucial to improve the chances of recovery and prevent long-term complications. The focus is on addressing the cause, providing supportive care, and preventing further kidney damage.