Acute kidney injury (AKI) is treated by addressing the underlying cause, managing fluid balance, stopping medications that harm the kidneys, and supporting the body while kidney function recovers. There is no single drug that reverses AKI. Treatment is about removing what’s damaging the kidneys, keeping the body’s chemistry stable, and giving the kidneys the conditions they need to heal.
AKI ranges from mild to severe, staged 1 through 3 based on how much kidney function has dropped. Stage 1 involves a modest rise in creatinine (a waste product the kidneys normally filter). Stage 3 means creatinine has tripled or the kidneys have nearly stopped producing urine. The stage determines how aggressively treatment needs to be managed and whether dialysis becomes necessary.
Finding and Fixing the Cause
The first priority is identifying why the kidneys are failing, because treatment depends entirely on the cause. AKI falls into three broad categories: not enough blood reaching the kidneys (prerenal), direct damage to kidney tissue (intrinsic), and a blockage preventing urine from draining (postrenal). Each requires a different approach.
Prerenal AKI is the most common type. It happens when blood flow to the kidneys drops, often from dehydration, severe blood loss, heart failure, or a dangerous drop in blood pressure. The fix here is restoring blood volume and circulation. Intrinsic AKI involves damage to the kidney cells themselves, caused by toxins, certain medications, infections, or inflammation. Treatment focuses on removing the offending agent and supporting the kidneys through recovery. Postrenal AKI results from something physically blocking urine flow, like kidney stones, an enlarged prostate, or a tumor pressing on the urinary tract.
Treating a Urinary Blockage
When AKI is caused by an obstruction, the priority is draining urine as quickly as possible. A blocked kidney that’s also infected is a medical emergency requiring immediate drainage. Even without infection, prompt intervention is needed when kidney function is declining or pain is uncontrollable.
For lower blockages (near the bladder or urethra), a catheter inserted through the urethra is usually the first step. This provides fast, complete bladder decompression. For blockages higher up, such as a stone lodged in the ureter, a stent can be placed inside the ureter to hold it open. When a stent can’t be placed, a percutaneous nephrostomy may be needed, where a small tube is inserted through the back directly into the kidney to drain urine. Once the blockage is relieved, kidney function often begins recovering within hours to days.
Restoring Fluid Balance
Fluid management is one of the trickiest parts of AKI treatment. Many patients arrive dehydrated or with low blood pressure, and they need IV fluids to restore blood flow to the kidneys. But too much fluid is dangerous: fluid overload in AKI patients is associated with increased mortality.
When fluids are needed, balanced crystalloid solutions (like lactated Ringer’s) are preferred over normal saline. Normal saline contains high levels of chloride, which can worsen kidney function and disrupt the body’s acid-base balance. Clinical trials have shown that using balanced fluids instead of normal saline improves kidney outcomes in both critically ill and non-critically ill patients, though the individual benefit is small. Doctors monitor fluid status closely throughout treatment, adjusting based on blood pressure, urine output, and signs of swelling or fluid accumulation in the lungs.
Stopping Harmful Medications
One of the most impactful steps in treating AKI is reviewing every medication a patient takes and pausing anything that could be making things worse. Several common drug classes are routinely held during an AKI episode:
- Anti-inflammatory painkillers (NSAIDs) like ibuprofen and naproxen reduce blood flow to the kidneys and are stopped immediately.
- Blood pressure medications that act on the renin-angiotensin system (ACE inhibitors and ARBs) alter pressure inside the kidney’s filtering units. These are typically paused and replaced with alternative blood pressure drugs if needed.
- Diuretics (water pills) can worsen dehydration and are usually held, especially potassium-sparing types.
- Metformin, a common diabetes medication, is stopped because it can accumulate to dangerous levels when kidney filtration drops.
- Certain antibiotics, particularly aminoglycosides, are avoided or dose-adjusted because they’re directly toxic to kidney cells.
- Lithium and trimethoprim are also held or reduced when possible.
If a patient was taking cholesterol-lowering medications and the AKI was caused by muscle breakdown (rhabdomyolysis), those are stopped too. Otherwise, statins can generally continue with monitoring. Once kidney function recovers, many of these medications can be carefully restarted.
Managing Dangerous Potassium Levels
When the kidneys stop filtering properly, potassium builds up in the blood. This is one of the most immediately dangerous complications of AKI because high potassium can cause fatal heart rhythm problems. Treatment happens in layers, depending on severity.
If potassium levels are critically high and the heart’s electrical activity is affected, the first step is stabilizing the heart muscle with IV calcium, which acts as a protective buffer within minutes. Next, medications are used to temporarily shift potassium out of the bloodstream and into cells, buying time. Insulin (given with sugar to prevent low blood sugar) and IV bicarbonate both accomplish this shift. These are temporary measures. The potassium is still in the body; it’s just been moved out of the danger zone.
To actually remove excess potassium from the body, the options are limited when the kidneys aren’t working. Oral medications that bind potassium in the gut can help over hours to days, but they’re too slow for emergencies. Dialysis is the definitive treatment when potassium can’t be controlled with medications alone.
When Dialysis Is Needed
Dialysis in AKI is a temporary bridge, not a permanent sentence. It’s used when the kidneys are too damaged to maintain safe body chemistry on their own. The main reasons dialysis gets started include dangerously high potassium that doesn’t respond to medication, severe fluid overload causing breathing difficulty, a buildup of metabolic acids the body can’t correct, or toxic levels of waste products causing confusion or other symptoms.
Stage 3 AKI is where dialysis most commonly enters the picture. Two main approaches exist: standard hemodialysis, which filters the blood in sessions lasting several hours, and continuous dialysis, which runs around the clock at a slower pace and is used for patients who are too unstable to tolerate the rapid fluid shifts of standard sessions. For most patients, dialysis during AKI is temporary. Kidney function often recovers enough over days to weeks that dialysis can be stopped.
Nutritional Support During AKI
AKI dramatically changes what the body needs nutritionally. Patients who aren’t critically ill generally need about 25 to 30 calories per kilogram of body weight per day. For someone weighing 70 kg (about 154 pounds), that’s roughly 1,750 to 2,100 calories daily. Critically ill patients in the ICU are often started at lower calorie targets for the first three days, around 70% of their estimated needs, then gradually increased.
Protein is where things get nuanced. Patients with mild AKI who aren’t on dialysis need about 0.8 to 1.0 grams of protein per kilogram per day. But dialysis strips protein and amino acids from the blood, so patients on dialysis need more: at least 1.1 to 1.2 grams per kilogram, and up to 1.5 or even 1.7 grams in severely catabolic states where the body is breaking down its own muscle tissue. Undereating protein during AKI worsens muscle loss and delays recovery, so the old advice to severely restrict protein in kidney injury has largely been abandoned except in specific situations.
Recovery and Follow-Up
Most people with AKI do recover meaningful kidney function, but the timeline varies widely. Mild cases may resolve within days once the cause is addressed. Severe cases requiring dialysis can take weeks to months, and some patients are left with permanent kidney damage.
After discharge from the hospital, follow-up kidney function testing is recommended within 90 days. Patients with more significant residual damage need closer monitoring: those discharged with substantially reduced kidney function (stage 4 chronic kidney disease) should be seen within 90 days, while those with severe residual impairment (stage 5) or still requiring dialysis at discharge should have a nephrology review within 30 days.
Having even one episode of AKI increases the long-term risk of developing chronic kidney disease, cardiovascular disease, and future AKI episodes. During recovery, avoiding nephrotoxic medications, staying well-hydrated during illness, and keeping blood pressure and blood sugar controlled all help protect remaining kidney function. Medications that were paused during the acute episode are reintroduced one at a time, with kidney function checked after each restart to make sure the kidneys can handle them.