Health Encyclopedia
Analgesic nephropathy
Definition
Analgesic nephropathy involves damage to one or both kidneys caused by overexposure to mixtures of medications, especially over-the-counter pain remedies (analgesics).
Alternative Names
Phenacetin nephritis; Nephropathy - analgesicCauses
Analgesic nephropathy involves damage within the internal structures of the kidney. It is caused by long-term use of analgesics, especially over-the-counter (OTC) medications that contain phenacetin or acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin or ibuprofen.
The excessive use may equal about three pills per day for 6 years. This frequently occurs as a result of self-medicating, often for some type of chronic pain.
Analgesic nephropathy occurs in about 4 out of 100,000 people, mostly women over 30. The rate has decreased significantly since phenacetin is no longer widely available in OTC preparations.
Risk factors include:
- Use of OTC analgesics containing more than one active ingredient
- Chronic headache
- Chronic backache or musculoskeletal pain
- Emotional or behavioral changes
- History of dependent behaviors including smoking, alcoholism, and excessive use of tranquilizers
- Pain with menstrual periods
Persons with this condition may also have a history of the following conditions:
- Urinary tract infections (see acute UTI)
- Interstitial nephritis
- Renal calculi
- Prerenal azotemia
- Congestive heart failure
- Blood volume depletion (such as dehydration)
Symptoms
- Weakness
- Fatigue
- Increased urinary frequency or urgency
- Blood in the urine
- Flank pain or back pain, renal colic (occasional)
- Decreased urine output
- Decreased alertness
- Decreased sensation, numbness (especially of extremities)
- Nausea, vomiting
- Easy bruising or bleeding
- Swelling, generalized
Exams and Tests
A physical examination may show signs of interstitial nephritis or kidney failure.
Blood pressure may be high. The doctor may hear abnormal heart or lung sounds when listening to the chest with a stethoscope. There may be signs of premature skin aging.
Lab tests may show blood and pus in the urine, with or without signs of infection. There may be mild or no loss of protein in the urine.
Tests that may be done include:
- Complete blood count
- Examination of sediment or tissue passed in the urine
- Intravenous pyelogram (IVP)
- Toxicology screen
- Urinalysis
Treatment
The primary goals of treatment are to prevent further damage and to treat any existing kidney failure. The health care provider may tell you to stop taking all suspect painkillers, particularly OTC medications.
Signs of kidney failure should be treated as appropriate. This may include diet changes, fluid restriction, dialysis or kidney transplant, or other treatments.
Counseling, behavioral modification, or similar interventions may help you develop alternative methods of controlling chronic pain.
Outlook (Prognosis)
The damage to the kidney may be acute and temporary, or chronic and long term.
Possible Complications
- Acute renal failure
- Chronic renal failure
- Interstitial nephritis
- Renal papillary necrosis (tissue death)
- Urinary tract infections, chronic or recurrent
- Hypertension
- Transitional cell carcinoma of the kidney or ureter
When to Contact a Medical Professional
Call your health care provider if you have signs of this condition, especially if there has been a history of use of painkillers.
Call your health care provider if blood or solid material is present in the urine, or if your urine output decreases.
Prevention
Follow the directions of the health care provider when using medications, including OTC medications. Do not exceed the recommended dose of medications without the supervision of the health care provider.
Reviewed By: Charles Silberberg, DO, Private Practice specializing in Nephrology, Affiliated with New York Medical College, Division of Nephrology, Valhalla, NY. Review provided by VeriMed Healthcare Network.
