OVERVIEW

What is Analgesic Nephropathy?

Analgesic nephropathy is a chronic kidney disease caused by long-term excessive use of analgesics, including combination analgesics (such as various compound preparations containing caffeine or codeine), acetaminophen, and nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin.

The most prominent features of analgesic nephropathy are renal papillary necrosis and chronic interstitial nephritis. The clinical manifestations of analgesic nephropathy are nonspecific, but patients often have a history of pain.

Once diagnosed with analgesic nephropathy, the use of analgesics must be discontinued immediately. Without this measure, the patient's kidney function will continue to deteriorate, potentially leading to urinary tract malignancies and atherosclerotic diseases.

Is Analgesic Nephropathy Common?

Analgesic nephropathy primarily affects women over 45 years of age with a history of long-term analgesic use. It was once a relatively common cause of chronic kidney disease, but its incidence has significantly declined due to restrictions on phenacetin and combination analgesics.

SYMPTOMS

What are the common manifestations of analgesic nephropathy?

The clinical manifestations of analgesic nephropathy are nonspecific, meaning the symptoms are also common in other diseases. Possible symptoms include:

• Laboratory findings: Elevated creatinine or abnormal urinalysis results.
• Back pain, headache.
• Hematuria.
• Recurrent urinary tract infections.
• Gastrointestinal symptoms, peptic ulcers.
• Hypertension.
• Fatigue.

What are the manifestations of mid-to-late-stage analgesic nephropathy patients?

Hypertension and anemia are common in mid-to-late-stage analgesic nephropathy patients.

Does taking phenacetin or its compound preparations always cause kidney damage?

Not necessarily.

If taken occasionally, these drugs do not accumulate in the body and will not have adverse effects.

However, with long-term use, regular blood and urine tests, as well as blood biochemistry tests, are necessary to assess whether kidney function has been impaired. If issues arise, prompt symptomatic treatment should be pursued.

Can analgesic nephropathy develop into cancer?

It is possible. Approximately 8%–10% of analgesic nephropathy patients may develop urinary tract malignancies, which typically become apparent after 15–25 years of analgesic abuse.

Analgesic nephropathy is the most common cause of bladder cancer in women under 50.

However, the use of nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin is not associated with urinary tract malignancies.

What diseases might analgesic nephropathy cause?

Besides progressive kidney damage, the main complications of analgesic nephropathy include two other conditions: urinary tract malignancies and atherosclerotic diseases.

How do analgesic nephropathy patients present with atherosclerotic diseases?

Patients with analgesic nephropathy are more likely to experience premature aging, early graying of hair, and atherosclerotic vascular diseases (including myocardial ischemia and thrombotic stroke).

CAUSES

What causes analgesic nephropathy?

The occurrence of analgesic nephropathy is related to the dosage and duration of analgesic use. Studies show that cumulative use of single or combined analgesics exceeding 3.0 kg, or daily intake of 1.0 g for more than 3 years, increases the risk of developing analgesic nephropathy.

These analgesics include compound analgesics, acetaminophen, and nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin.

Who is at higher risk of analgesic nephropathy?

Risk factors for analgesic nephropathy include children, the elderly, pre-existing kidney disease or renal insufficiency (such as chronic interstitial tubular disease, renal arteriosclerosis, diabetic nephropathy, and nephrotic syndrome), hypovolemia, heart failure, hypertension, cirrhosis with ascites, and infections.

Is analgesic nephropathy hereditary?

No.

DIAGNOSIS

How to Diagnose Analgesic Nephropathy?

When diagnosing analgesic nephropathy, doctors primarily rely on medical history and urinalysis results. This includes a history of long-term, heavy use of analgesic medications and abnormal urinalysis findings.

What Tests Are Needed for Analgesic Nephropathy?

A non-contrast CT scan is usually required. The CT diagnostic criteria for analgesic nephropathy include bilateral kidney shrinkage, irregular renal contours, and renal papillary calcification.

However, due to the current rarity of phenacetin use, the sensitivity of non-contrast CT scans is relatively low.

What Symptoms in Analgesic Nephropathy Patients Should Raise Suspicion of Urinary Tract Tumors?

Patients with analgesic nephropathy should be alert to the possibility of urinary tract tumors if they experience gross hematuria. They should seek medical evaluation, including urine cytology, cystoscopy, and non-contrast CT and/or MRI scans.

Which Diseases Are Easily Confused with Analgesic Nephropathy?

• Analgesic nephropathy can be easily confused with sickle cell disease, chronic pyelonephritis, and diabetes, but these can be differentiated through medical history.

• Analgesic nephropathy may also be mistaken for renal tuberculosis, which can be distinguished through urine culture.

TREATMENT

Can Analgesic Nephropathy Heal on Its Own?

If the use of analgesics is not discontinued, such as compound analgesics, acetaminophen, and non-steroidal anti-inflammatory drugs like aspirin, kidney function will continue to decline, and the condition will gradually worsen.

How Is Analgesic Nephropathy Treated?

There is currently no targeted treatment for analgesic nephropathy. The primary treatment method is to discontinue the use of analgesic drugs, such as compound analgesics, acetaminophen, and non-steroidal anti-inflammatory drugs like aspirin.

Can Analgesic Nephropathy Be Cured?

• Whether analgesic nephropathy can be alleviated or cured depends on the severity of kidney damage and whether analgesic drug use is stopped.
• After stopping analgesics, most patients with mild conditions can maintain stable or slightly improved kidney function.
• In advanced stages of kidney disease, the condition may continue to worsen even after stopping analgesics. Long-term use of analgesics may also lead to urinary tract malignancies and atherosclerotic diseases.

DIET & LIFESTYLE

What should patients with analgesic nephropathy pay attention to in their diet?

• Maintain a low-salt and low-fat diet, with a daily sodium chloride intake of 2-3g, and control the intake of potassium, phosphorus, sodium, etc.

• For protein intake, if the patient's kidney function is normal, no special adjustment is needed. If kidney dysfunction is present, it is recommended to consume high-quality protein, such as fish, eggs, dairy, and soy protein.

• Eat more fruits and vegetables, consume low-calorie and high-fiber foods, and drink plenty of water.

Does analgesic nephropathy require follow-up examinations? How is it monitored?

Follow-up examinations are necessary. The doctor will arrange the frequency based on the clinical situation, primarily monitoring the glomerular filtration rate and checking for the occurrence of hematuria in patients with analgesic nephropathy.

PREVENTION

Can Analgesic Nephropathy Be Prevented? How to Prevent Analgesic Nephropathy?

Based on the causes of analgesic nephropathy, the following measures can be taken to prevent it:

• Use nonsteroidal anti-inflammatory drugs (NSAIDs) at therapeutic doses for short-term periods.

• Avoid compound analgesics containing caffeine or codeine.

• Avoid NSAIDs if risk factors are present.

How Can Patients with Analgesic Nephropathy Prevent Other Diseases?

Patients with analgesic nephropathy should discontinue analgesic drugs as much as possible under medical supervision and undergo regular follow-ups and continuous monitoring to help prevent complications. Specific measures include:

• If analgesics are discontinued, perform urine cytology once a year for the first few years after stopping.

• If analgesics are continued, perform annual checkups indefinitely.