Analgesic nephropathy is kidney damage which occurs with long-term, daily use of over-the-counter pain medication (also known as pain relievers, painkillers, or analgesics). It can also occur when pain relievers are not used as directed.
Definition & Facts
Analgesic nephropathy refers to kidney damage including renal papillary necrosis and interstitial nephritis that results from the use of analgesics. The former involves the death of cells in the renal papilla which are where the renal ducts open and where urine flows from the kidneys into the ureters. Interstitial nephritis is when the interstitium of the kidney becomes inflamed.
If left untreated, analgesic nephropathy can lead eventually to chronic kidney failure or end-stage renal disease. This condition mostly affects those over the age of 45 and is most often asymptomatic. It is estimated to affect 4 out of every 100,000 people and to be more common among women over the age of 30 than other demographics.
Symptoms & Complaints
High blood pressure (hypertension) and anemia are also common symptoms of this disease. Left untreated and in more advanced cases, end-stage renal disease can occur. Some other symptoms may include the following:
- Confusion and drowsiness
- Numbness in the lower extremities
- Easy bruising
- Swelling throughout the body
The primary cause of analgesic nephropathy is long-term use of over-the-counter pain medication. Taking six pills or more a day for at least three years is considered long-term use according to the National Institutes of Health.
Pain relievers that can cause this disorder include acetaminophen (also known as paracetamol), phenacetin, aspirin, and nonsteroidal anti-inflammatory drugs (NSAID's) which include ibuprofen, ketoprofen, and naproxen. Medications which combine these drugs are also more likely to result in the disease with extended use. This includes medications that combine aspirin, caffeine, and acetaminophen for example.
In addition to long-term use, people with lupus, kidney disease, or alcohol abuse could have a sudden onset of analgesic nephropathy when using painkillers. How this use of pain medication brings about kidney damage is not completely clear. Some analgesics are only metabolized by the kidneys as opposed to being metabolized by the liver.
Diagnosis & Tests
A physical examination will likely be performed as well as an inquiry into the patient's medical history including their long-term or recent over-the-counter painkiller use and their history of diseases like lupus and alcohol abuse.
The doctor may check for high blood pressure, abnormal heart and lung sounds, and swelling in the lower extremities. A complete blood count may be done to check for anemia and other blood abnormalities. A urinalysis may show white blood cells, protein (proteinuria), and possibly blood in the urine.
Urine tests may reveal the presence of painkillers. If the results of these tests are positive, the doctor may order additional tests, including a kidney X-ray to see if there are signs that necrosis or death of the renal papillary has occurred.
A computed tomography (CT) scan may be ordered to confirm a diagnosis. The CT scan may help determine if the kidney has shrunk in size or if there are any abnormalities in the shape of the kidney. It may also confirm the presence of papillary calcification or calcium such as one would find in kidney stones.
Treatment & Therapy
Stopping the use of analgesics is necessary to treat the disease. If the disease hasn’t progressed too far, stopping painkillers can halt the disease and reverse kidney damage. Patients who have issues with pain might also be shown alternative ways to manage their symptoms. Stress reduction, relaxation techniques, yoga, meditation, physical therapy, and exercise all may be suggested as alternatives for pain relief.
If the disease is not addressed, stopped, and reversed, dietary restrictions for those with chronic kidney disease may be recommended. Some of these restrictions include reducing salt, potassium, phosphates and proteins while increasing the amount of vitamin B, vitamin C, and iron in one's diet. Working with a dietician may be helpful to avoid malnutrition. She might recommend having several smaller meals throughout the day.
Depending on the condition's severity, chronic kidney disease may also require dialysis and a possible kidney transplant. It is also necessary to reduce fluid intake as the kidneys are needed to process fluid as excess fluid can lead to high blood pressure and swelling in the legs.
Prevention & Prophylaxis
Various biofeedback and relaxation techniques can be used to help overcome the reliance on pain medications for chronic pain. If a patient does need to use painkillers daily, it is best to have regular testing of the kidney function so that any adverse effects can be monitored.
To the extent that this condition may be brought about by using painkillers in concert with alcohol abuse, people with alcohol use disorder should seek treatment, which could include counseling or group therapy in order to reduce their risk.