Analgesic nephropathy refers to kidney damage caused by regular, long-term use of pain medicines. Short-term, occasional use of these medicines does not seem to cause kidney damage.
Pain medicines may cause kidney damage when a person takes more than 6 to 8 pills every day for several years. This kind of long-term use of pain relievers can occur in people with chronic headaches, back pain, or other chronic pain syndromes.
These medicines cause kidney damage in two different ways. The first way is called chronic interstitial nephritis. In this disorder, inflammatory cells cause scarring and result in damaged, shrunken kidneys. The second way is called papillary necrosis. In this case, the inner kidney dies and sloughs off, leaving a damaged kidney. The damage due to these pain medicines occurs slowly, over many years. It is usually not diagnosed until severe damage has occurred.
Analgesic nephropathy is caused by long-term, regular use of pain medicines. These medicines include acetaminophen, aspirin, and nonsteroidal anti-inflammatory drugs, or NSAIDs. Ibuprofen and naproxen are examples of NSAIDs. Those with chronic pain are more likely to use these medicines in a way that causes kidney damage. Medicines that combine two or more analgesics together with caffeine or codeine are most likely to cause damage. These medicines are often sold as powders containing acetaminophen and aspirin with caffeine.
Signs and symptoms of analgesic nephropathy usually come on slowly and may include:
Symptoms of kidney failure may include:
Diagnosis of analgesic nephropathy begins with a history and physical exam. Kidney function tests will be ordered. A blood test called CHEM-7 can help diagnose kidney damage or failure. A urinalysis can also help detect problems with kidney function.
Imaging tests, such as an ultrasound or a CT scan, may be ordered. These tests check the size of the kidneys and detect some problems. A biopsy of the kidney may be done as well. This involves inserting a special needle through a person's back and into the kidney. A small piece of the kidney is removed with the needle. This sample is sent to the lab for examination and testing.
Analgesic nephropathy can be prevented by limiting the use of pain medicines.
Kidney function may improve if this condition is caught early and the person stops taking the pain medicines. However, kidney failure is often present by the time the diagnosis is made. This type of kidney damage is not usually reversible.
A person with kidney failure needs dialysis or a kidney transplant to survive. Dialysis is a procedure to filter the blood. It requires a person to be hooked up to a special blood-filtering machine, sometimes as often as three times a week. This continues for life or unless the person gets a kidney transplant.
Analgesic nephropathy is not contagious and poses no risks to others.
A person with analgesic nephropathy is advised to stop using pain medicines. If the condition is caught early, this may be the only treatment that is needed. If kidney failure is present, the person will need either dialysis or a kidney transplant. The person may also need treatment for high blood pressure.
Dialysis has many side effects, including infection, salt imbalances, and even death. Surgery can cause bleeding, infection, or allergic reaction to anesthesia.
After a kidney transplant, a person must take powerful medicines to prevent the body from rejecting the new kidney. These medicines increase the person's risk of infections. They may damage the new kidney and cause other side effects. Blood pressure medicines may cause fatigue, lightheadedness, and erectile dysfunction.
Those with only mild kidney damage who stop using pain medicines may be able to lead a normal life. Those with kidney failure usually need treatment for the rest of their lives.
Kidney function is usually monitored with regular blood and urine tests. Any new or worsening symptoms should be reported to the healthcare provider.
Author:Rajnish K. Dhingra, MD
Editor:Crist, Gayle P., MS, BA
Reviewer:Adam Brochert, MD
Harrison's Principles of Internal Medicine, 1998, Fauci et al.