Sudden drop in urine output? It could be acute kidney failure

Acute kidney failure is an unpredictable condition that should be suspected when there is a sudden decrease in urine output.

Kim Jin-guk, a professor of nephrology at Soonchunhyang University Bucheon Hospital, warns that even healthy individuals can develop acute kidney failure within hours or days due to various causes.

There are three main causes of acute kidney failure: pre-renal, renal (intrinsic), and post-renal. Pre-renal failure is caused by a reduction in blood supply to the kidneys. Severe dehydration due to vomiting, diarrhea, or fever is a common cause, along with bleeding, heart failure, cirrhosis, and sepsis.

Renal acute kidney failure results from issues within the kidney itself, such as glomerular, tubular, or vascular diseases. Post-renal acute kidney failure occurs when urinary stones or tumors obstruct the flow of urine.

Risk factors for acute kidney failure include low blood pressure, congestive heart failure, sepsis, diabetes, rhabdomyolysis, nephrotoxic drugs or contrast media, severe dehydration, shock, and burns. The risk increases further for individuals with chronic kidney, heart, liver, or lung diseases, those who have undergone heart surgery, and older adults.

In acute kidney failure, the kidneys lose their ability to filter nitrogenous waste effectively, leading to hypernitrogenemia. Symptoms can include decreased urine output (oliguria), nausea, vomiting, loss of appetite, edema, high blood pressure, and shortness of breath. In severe cases, it can progress to coma.

A hallmark symptom is a sudden decrease in urine output. About 50 percent of acute kidney failure cases present with oliguria, defined as urine output of less than 400 mL per day. However, some patients may not experience this symptom and instead have non-oliguric acute kidney failure, where urine output is partially maintained.

Diagnosis typically involves blood tests to measure creatinine and urea nitrogen. Acute kidney failure is diagnosed if serum creatinine increases by 50% or more within seven days, by 0.3 mg/dL or more within 48 hours, or if urine output drops below 0.5 mL/kg/h for more than six hours.

Additional diagnostic tools include blood and urine tests, ultrasound, and kidney biopsy if necessary. Treatment focuses on addressing the underlying cause and preventing further kidney damage.

Symptom management includes fluid control, electrolyte and acid-base balance, and proper nutrition. In severe cases of uremia, hyperkalemia, metabolic acidosis, or fluid overload (e.g., pulmonary edema), hemodialysis may be required. During recovery, patients may experience increased urine output and diuresis, making dehydration prevention crucial.

Preventive strategies include drinking enough fluids (if there is no edema), consuming moderate amounts of salt and protein, avoiding processed foods, and steering clear of medications or supplements that strain the kidneys. Regular exercise also helps reduce risk.

"If you experience symptoms of acute kidney failure, such as decreased urine output, it’s important to visit a healthcare provider as soon as possible," said Professor Kim. "Early detection can lead to recovery without dialysis and prevent complications. However, if left untreated, it can progress to chronic kidney failure or result in serious conditions like pulmonary edema and heart failure."

"Maintaining kidney health is essential for overall health," he added. "Although acute kidney failure is unpredictable, proper lifestyle habits and regular checkups can reduce the risk and prevent kidney disease."