The long-term use or abuse of acetaminophen can cause irreparable kidney damage. Individuals who regularly use acetaminophen for pain relief as directed are not considered at risk for kidney damage. Those who misuse the over-the-counter (OTC) analgesic medication are considered at greatest risk for acetaminophen toxicity, which is an accumulation of the drug within the body that occurs when the kidneys become unable to effectively expel the substance at the rate at which it is taken in.
Acetaminophen is a painkiller that is available over the counter. When taken as directed, the drug poses no risk to renal, or kidney, function. Under normal circumstances, the drug functions to alleviate pain and is then filtered through the kidneys and expelled as waste. In cases where the drug is misused or abused, it accumulates in the body. Over time, the kidneys are unable to expel the drug at a rate sufficient to compensate for its intake. As a result, toxic levels of acetaminophen and kidneys' ability to function causes damage that can quickly become permanent.
Individuals with acetaminophen toxicity can remain asymptomatic for several hours. Signs and symptoms of overdose can include nausea, loss of appetite and a general feeling of malaise. It is not uncommon for some people to experience significant abdominal discomfort, jaundice and vomiting. Once kidney function becomes impaired, additional signs can include dehydration, decreased urination and swelling resulting from a buildup of fluid in the body. In some cases, the individual may lose consciousness, which is a medical emergency requiring immediate treatment.
Several factors influence the absorption rate of acetaminophen and kidneys' function and the subsequent damage that may result. Individuals of advanced age and those with existing medical conditions, including kidney disease, are considered at greatest risk for acetaminophen toxicity and kidney damage. Since acetaminophen is broken down in the liver, those with impaired liver function or disease are also at risk for complication. Acetaminophen toxicity primarily affects the kidneys in one of two ways.
If the kidneys suddenly stop functioning normally, acute kidney failure has occurred. Acute kidney failure can develop in as little as a few hours and contribute to irreversible kidney damage. Those who regularly use acetaminophen over the long term, for instance several months or years, are at greatest risk for a condition known as analgesic nephropathy. A form of chronic kidney disease, analgesic nephropathy necessitates permanent reliance on dialysis. Toxic levels of acetaminophen and kidneys' dysfunction can require a kidney transplant if extensive, irreparable damage has occurred.
When acetaminophen toxicity is suspected, a battery of tests is usually ordered. Following a physical examination, blood and urine analysis are performed to check for signs of acetaminophen toxicity. Some imaging tests may be performed to evaluate kidney function and determine the extent of any damage the kidneys may have sustained.
The primary goal of treatment for toxic levels of acetaminophen and kidneys that are at risk for damage is to flush the toxin from the body. All use of acetaminophen must be halted to avoid further toxicity. If recent acetaminophen use has occurred, activated charcoal may be given to clear any remaining acetaminophen from the digestive tract. An antidote, called N-acetylcysteine (NAC), is given either orally or intravenously to counteract the effects of acetaminophen toxicity. If damage to the kidneys is not too significant, it may be reversed with antidotal treatment.
When irreparable kidney damage is sustained, long-term management of the condition is necessary to prevent further organ deterioration. Common approaches include dietary supplements, diuretics and, in some cases, dialysis. Medications designed to maintain proper potassium and calcium levels in the blood are also given to avoid further complications associated with acetaminophen and kidneys.