Acute kidney injury (AKI) is a sudden drop in kidney function that develops over hours to days, leading to a build‑up of waste products, fluid, and electrolytes in the body. It can occur in hospitalised patients after surgery or infections, but also in the community after dehydration, uncontrolled medicines, or poisoning. Early recognition and prompt treatment can make the difference between complete recovery and lifelong kidney damage.

This blog explains what AKI is, why it happens, how to spot symptoms, how doctors diagnose and treat it, and what recovery usually looks like.

What Is Acute Kidney Injury?

AKI is defined as a sudden decline in kidney function over hours to a few days, usually detected by

• A rapid rise in serum creatinine (waste marker in blood).
  
• A fall in urine output (oliguria) or complete stoppage (anuria).
  

Unlike chronic kidney disease (CKD), which develops slowly, AKI is abrupt and potentially reversible if managed quickly.

 

Major Causes of AKI

Doctors often group causes into three broad categories:

1) Pre‑renal (reduced blood flow to kidneys)

Anything that drastically lowers blood flow or blood volume can trigger AKI:

• Severe dehydration from vomiting, diarrhoea, or poor intake.
  
• Heavy blood loss, shock, or severe infections (sepsis).
  
• Heart failure or very low blood pressure.
  

If corrected early, pre‑renal AKI often reverses without permanent damage.

2) Intrinsic (damage inside the kidneys)

Here, the kidney tissues themselves are injured:

• Acute tubular necrosis from prolonged low blood flow or toxins.
  
• Glomerulonephritis (immune‑mediated inflammation of filters).
  
• Acute interstitial nephritis from allergic reactions to medicines.
  
• Direct toxic injury from certain drugs, contrast dyes, or poisons.
  

3) Post‑renal (blocked urine outflow)

Obstruction anywhere in the urinary tract:

• Enlarged prostate, kidney stones, tumours, or strictures blocking both kidneys or the bladder outlet.
  
• Prolonged obstruction increases back pressure and damages kidneys.
  

In India, common triggers include infections, dehydration from diarrhoeal illness, uncontrolled use of painkillers or indigenous remedies, sepsis, and obstructive uropathy in older men.

 

Risk Factors: Who Is More Vulnerable?

• Older age.

• Diabetes, hypertension, or known CKD.

• Heart failure, liver disease.

• Major surgery, especially cardiac or abdominal.

• Use of nephrotoxic drugs (NSAIDs, some antibiotics, contrast dyes) without proper monitoring.

These patients need extra care with hydration and medication choices.

Symptoms and Warning Signs

AKI can be silent—sometimes only blood tests reveal it. When present, symptoms include:

• Reduced urine output – passing much less urine than usual or almost none.
  
• Swelling (edema) – especially in legs, ankles, feet, or around eyes due to fluid retention.
  
• Shortness of breath – from fluid in lungs or severe anaemia.
  
• Fatigue and weakness – as toxins build up.
  
• Confusion or drowsiness – due to electrolyte imbalance or uraemia.
  
• Nausea, loss of appetite, or vomiting.
  
• Chest pain or pressure in severe cases.
  
• High blood pressure or, occasionally, low blood pressure.
  
• Pain in the flank (side of back) if obstruction or infection is present.
  

Severe AKI can lead to seizures, coma, or life‑threatening arrhythmias.

Any sudden drop in urine plus swelling or breathlessness needs immediate evaluation.

 

How Is AKI Diagnosed?

Doctors combine clinical assessment with investigations:

• History and examination – recent illnesses, fluid losses, drugs taken, urinary symptoms, prostate issues.
  
• Blood tests – serum creatinine, urea, electrolytes (especially potassium), complete blood count.
  
• Urine tests – dipstick, microscopy, sometimes protein and sediment analysis.
  
• Ultrasound – to check kidney size and rule out obstruction.
  
• Special tests (autoimmune markers, biopsy) in selected intrinsic disease.
  

AKI staging (based on creatinine rise and urine output) helps predict severity and guide management.

 

Treatment: Addressing the Cause and Supporting the Kidneys

Management focuses on treating the underlying cause, preventing further injury, and supporting the body while kidneys recover.​

1) Stabilisation and Removing Triggers

• Restore blood volume and blood pressure with IV fluids and, if needed, medications to support circulation.​
• Stop or adjust nephrotoxic drugs (NSAIDs, some antibiotics, contrast, certain herbal/indigenous remedies).​
• Treat underlying problems like sepsis, heart failure, or obstruction.

2) Treating the Specific Cause

• Pre‑renal AKI: Fluids, blood transfusion (if major blood loss), treatment of infection or shock.
• Intrinsic AKI: Manage glomerulonephritis or interstitial nephritis with steroids or immunosuppressants where indicated; avoid further toxins.​
• Post‑renal AKI: Relieve blockage by catheter insertion, stenting, or surgery (e.g., for enlarged prostate or stones).​

3) Dialysis (Renal Replacement Therapy)

Dialysis may be needed temporarily if:​

• Potassium is dangerously high (hyperkalaemia).
• There is severe fluid overload causing breathlessness.
• Waste products are extremely high with symptoms (nausea, confusion, pericarditis).
• Certain drug poisonings are present.

Many AKI patients come off dialysis once kidneys recover sufficiently; only a minority remain dialysis‑dependent long term.​

 

Recovery After Acute Kidney Injury

Recovery can follow different patterns:​

• Full recovery: Creatinine returns close to baseline and urine output normalises within days to weeks.
• Partial recovery: Kidney function improves but remains mildly reduced, sometimes progressing to chronic kidney disease (CKD).
• No recovery: In some severe cases, especially with extensive damage or multiple comorbidities, kidneys do not regain function and the person transitions to chronic dialysis or transplant evaluation.

Key findings from studies:

• A significant proportion of patients who required dialysis for AKI recover enough to stop it within 90 days, but risk of future CKD and cardiovascular disease remains higher than in those without AKI.​
• Risk of non‑recovery is higher in older adults, those with pre‑existing CKD, severe sepsis, or prolonged hypotension.​

Follow‑up with nephrology after discharge is crucial, even if creatinine appears “normal” again.

 

Can AKI Be Prevented?

Not all AKI is preventable, but risk can be reduced by:​

• Staying well hydrated during illness, heat, and heavy exercise.
• Avoiding unnecessary over‑the‑counter painkillers (especially NSAIDs) and unregulated herbal remedies in at‑risk individuals.
• Informing doctors about existing kidney issues before contrast scans or surgeries.
• Controlling diabetes, blood pressure, and heart disease.
• Seeking prompt care for infections, diarrhoea, vomiting, or urinary blockage.

Hospitals can reduce AKI by monitoring creatinine and urine output closely in high‑risk patients and adjusting drugs early.

 

FAQs

1) If my creatinine returns to normal after AKI, am I completely out of danger?
Improvement to near‑baseline creatinine is an excellent sign, but research shows that people who have had any episode of AKI remain at higher long‑term risk of CKD and cardiovascular disease than those who never had AKI. Regular follow‑up (blood pressure, creatinine, urine albumin) and healthy lifestyle measures are recommended even after apparent full recovery.​

2) Does needing dialysis during AKI mean I will need it for life?
Not necessarily. A substantial proportion of patients who require dialysis for AKI recover enough kidney function to stop dialysis within weeks to months. The likelihood of coming off dialysis depends on age, baseline kidney function, cause and severity of AKI, and other illnesses. Nephrologists typically reassess kidney recovery over the first 60–90 days after AKI before labelling someone as having end‑stage kidney disease.​

3) Can I prevent AKI if I already have chronic kidney disease or diabetes?
While risk cannot be eliminated, it can be significantly reduced by strict control of blood sugar and blood pressure, avoiding nephrotoxic medicines, staying hydrated during illness, and informing every treating doctor about your kidney condition. Early recognition of warning signs—falling urine output, leg swelling, breathlessness, or sudden creatinine rise—allows timely interventions that may prevent progression to severe AKI.​