Acute Kidney Injury (AKI) Diagnosis, Treatment & Cost

✅Acute Kidney Injury Diagnostic Tests

Based on the clinical presentation and initial evaluation, a physician recommends tests to confirm the presence of acute kidney injury, determine its severity, identify the underlying cause, and assess for associated complications.

The following are the diagnostic tests for acute kidney injury that may be suggested for the diagnosis:

• Confirm AKI using laboratory criteria 
• Serum creatinine
• Urine output
• Laboratory investigations
• Blood tests
• Blood urea nitrogen (BUN)
• Estimated glomerular filtration rate (eGFR)
• Comprehensive metabolic panel
• Serum electrolyte
• Acid–base balance
• Urine examination
• Urine electrolytes 
• Urine studies
• Urine microscopy
• Protein/ creatinine ratio
• Advanced labs (selected patients)
• Serum & urine protein electrophoresis (especially in older adults)
• Novel biomarkers 
• Imaging studies
• Renal ultrasound
• Computed tomography (CT scan)
• Invasive studies (rare)
• Kidney biopsy

Confirm AKI using laboratory criteria 

Acute kidney injury is confirmed using the Kidney Disease: Improving Global Outcomes (KDIGO) criteria, which are based on changes in serum creatinine and urine output. According to KDIGO, AKI is diagnosed if there is:

• Serum creatinine: When kidney function suddenly declines, the kidneys cannot clear creatinine efficiently, causing its level in the blood to rise. A rapid increase in serum creatinine, therefore, indicates a reduction in glomerular filtration rate (GFR), which is a key feature of AKI. 
• An increase in serum creatinine ≥0.3 mg/dL (26.5 µmol/L) within 48 hours, or 
• An elevation in serum creatinine to ≥1.5 times baseline within 7 days.
• Urine output: In AKI, reduced kidney perfusion or intrinsic damage can lead to oliguria (low urine output). Measuring urine volume over time helps detect early kidney dysfunction.
• Urine output <0.5 mL/kg/hour for at least 6 hours.

Laboratory investigations

This is important for diagnosing acute kidney injury because they assess how well the kidneys are filtering waste, maintaining electrolyte balance, and regulating acid–base status. Lab tests include:

• Blood tests: These tests are the first step in evaluating suspected AKI. They measure waste products and electrolytes in the blood, helping detect sudden deterioration in kidney function. A rapid change from previous values supports an acute process rather than a chronic disease.
• Blood urea nitrogen (BUN): This measures the amount of urea, a waste product formed from protein metabolism. Normally, the kidneys eliminate urea effectively. Reduced filtration in AKI causes BUN levels to rise. A high BUN, especially when combined with increased serum creatinine, indicates compromised renal function. The BUN-to-creatinine ratio can also be used to distinguish between pre-renal causes (which are frequently increased) and intrinsic renal causes.
• Estimated glomerular filtration rate (eGFR): This test reflects how well the kidneys are filtering blood. In AKI, as creatinine levels rises, eGFR decreases, which indicates decreased filtration capacity of the kidneys. Although eGFR is more commonly used in chronic kidney disease, a sudden drop supports acute kidney dysfunction.
• Comprehensive metabolic panel (CMP): It measures creatinine, BUN, glucose, and electrolytes levels. This panel gives a complete assessment of kidney function and metabolic state. Abnormalities observed in a CMP, including increased creatinine and electrolyte imbalances, may indicate AKI.
• Serum electrolytes: Electrolytes such as sodium, potassium, chloride, and bicarbonate remain abnormal in AKI because the kidneys regulate electrolyte balance. Hyperkalemia (high potassium) is particularly important, as it can cause life-threatening cardiac arrhythmias. Hyponatremia or hypernatremia may reflect a fluid imbalance.
• Acid–base balance: It is assessed by measuring bicarbonate levels or arterial blood gases. In AKI, impaired acid excretion can lead to metabolic acidosis, indicated by low bicarbonate levels and decreased blood pH.

Urine examination 

It helps to determine the cause and type of kidney damage, whether pre-renal, intrinsic, or post-renal.

• Urine electrolytes: This test aids in assessing perfusion and tubular function. Pre-renal AKI causes the kidneys to store salt and water, resulting in low urine sodium levels (<20 mEq/L). Because the injured tubules cannot reabsorb sodium correctly in intrinsic renal injury, urine sodium levels are elevated (>40 mEq/L). These values can also be used to calculate the fractional excretion of sodium (FENa), which helps differentiate pre-renal from intrinsic causes.
  
• Urine studies: This study measures urine osmolality and specific gravity. In pre-renal AKI, the kidneys concentrate urine to conserve fluid, so urine osmolality is high. In intrinsic renal damage, the kidneys lose concentrating ability, leading to more dilute urine with lower osmolality. These findings support the underlying mechanism of kidney injury.
  
• Urine microscopy: This involves examining urine under a microscope. This can reveal characteristic findings:
• Muddy brown granular casts: suggest acute tubular necrosis
• Red blood cell casts: indicate glomerulonephritis
• White blood cell casts: suggest interstitial nephritis or infection
• Crystals: may suggest obstruction or toxin-related injury
  
• Protein/creatinine ratio: It measures the amount of protein excreted in urine relative to creatinine. In intrinsic kidney diseases, like in glomerular disorders, protein leakage increases due to damage to the filtration barrier. A high protein/creatinine ratio supports intrinsic renal causes rather than pre-renal causes.

Advanced labs (selected patients)

In certain patients, especially when the cause of AKI is unclear or when specific underlying diseases are suspected, advanced laboratory tests may be recommended.
These specialised tests include:

• Serum and urine protein electrophoresis (for elderly adults): These tests can reveal aberrant proteins in situations like multiple myeloma. These aberrant proteins can build up in the kidneys and harm the tissues, resulting in acute kidney injury. Identifying these proteins allows doctors to assess whether a plasma cell disease is the underlying cause of kidney damage.
• Novel biomarkers: When kidney cells are injured, they emit novel biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and interleukin-18 (IL-18). Measuring these markers in blood or urine detects acute kidney injury earlier than traditional methods.

Imaging studies

Imaging studies are important in evaluating acute kidney injury (AKI), especially to identify structural abnormalities and obstructive causes.

• Renal ultrasound 
• It is the first-line imaging test in suspected AKI. It helps assess kidney size, structure, and the presence of obstruction. In post-renal AKI, ultrasound may show hydronephrosis (dilation of the renal pelvis and calyces) due to blockage from kidney stones, tumors, or an enlarged prostate. 
• It can also detect bladder distension, suggesting urinary retention. Additionally, kidney size can help differentiate acute from chronic kidney disease—normal or enlarged kidneys are more typical in AKI, while small shrunken kidneys suggest chronic disease.
• Computed tomography (CT scan) 
• It provides more detailed imaging and is useful when ultrasound findings are unclear or when obstruction, stones, trauma, or tumors are strongly suspected. A non-contrast CT scan is helpful in detecting kidney stones causing obstruction. 
• CT imaging can also identify masses, abscesses, or structural abnormalities that may impair kidney function. However, contrast-enhanced CT scans are used cautiously in AKI because contrast agents can worsen kidney injury.

Invasive investigation 

It is rarely required AKI diagnosis, but it can be very important when the cause is unclear or when intrinsic renal disease is strongly suspected. 

• Kidney biopsy: Biopsy is particularly useful when patients have unexplained AKI, significant proteinuria, hematuria with red blood cell casts, or when autoimmune disease is suspected. By identifying the exact cause, a kidney biopsy guides targeted treatment decisions, such as the use of corticosteroids or immunosuppressive therapy.
  

✅Acute Kidney Injury Stages

✅Acute Kidney Injury Differential Diagnosis

✅Acute Kidney Injury Treatment Goals

Get Medical Second Opinion for Acute kidney injury (AKI) Treatment for Better Clarification

At PACE Hospitals, we are committed to providing our patients with the best possible care, and that includes offering second medical opinions with super specialists for treatment or surgery. We recommend everyone to get an expert advance medical second opinion, before taking decision for your treatment or surgery.

Based on the clinical presentation and laboratory evaluation, treatment of acute kidney injury focuses on identifying and managing the underlying cause, supporting kidney function, correcting fluid and electrolyte imbalances, and preventing complications.
Below are the acute kidney injury treatment options: 

Immediate assessment and stabilization

• Assess airways, breathing and circulation
• Hemodynamic optimisation (vasopressors for shock)
• Monitoring (e.g., serum creatinine, urine output staging)
• 
  

Non-pharmacological management

• Identify & treat the cause
• Fluid management
• Electrolyte and metabolic monitoring
• Dietary management
• Avoiding nephrotoxic drugs

Pharmacological management

• Management of hyperkalemia (Emergency if K⁺ >6.5 mmol/L)
• IV Calcium gluconate
• Shift potassium into cells
• Remove potassium through loop diuretics and dialysis
• Fluid overload
• IV loop diuretics
• Metabolic Acidosis
• IV sodium bicarbonate (if severe, pH <7.1)
• Specific Cause-Based Treatment
• Glomerulonephritis → Steroids / Immunosuppressants
• Rhabdomyolysis → Aggressive IV fluids
• Sepsis → IV antibiotics + supportive care
• Hypertension → Calcium channel blockers and beta blockers (dose-adjusted)

Procedural Management

• Renal Replacement Therapy (RRT)
• Hemodialysis
• Continuous Renal Replacement Therapy (CRRT)
• Urinary Catheterization

Surgical Management

• Relief of obstruction
• Ureteric stenting
• Percutaneous nephrostomy
• Surgery for underlying causes:
• Prostatic enlargement
• Tumors
• Renal stones causing obstruction

Immediate Assessment and Stabilization

Assessment of airway, breathing, and circulation (ABC)

In acute kidney injury, immediate assessment starts with checking the airway, breathing, and circulation (ABC) to ensure the patient is stable and adequately perfused. 

Hemodynamic optimization

This includes the use of intravenous(IV) fluids and vasopressors in cases of shock, which helps to restore and maintain adequate renal perfusion pressure. In conditions such as sepsis or severe dehydration, low blood pressure may reduce blood flow to the kidneys, resulting in pre-renal AKI or acute tubular necrosis. Vasopressors help to increase systemic blood pressure and improve organ perfusion, which supports kidney function and prevents further injury.

Monitoring 

It includes serial measurements of serum creatinine and close observation of urine output, allowing early detection of worsening kidney function and helping stage the severity of AKI.

Non-pharmacological Management

This plays a central role because it focuses on correcting the underlying problem, preventing further kidney damage, and allowing the kidneys time to recover.

Identify & treat the cause

The first and most important step is identifying and treating the underlying cause. AKI may result from dehydration, blood loss, infection, urinary obstruction, or reduced blood flow to the kidneys. Correcting these issues—by restoring circulation, relieving obstruction, or treating infection—removes the stress on the kidneys and helps prevent continued injury.

Fluid management

In cases of dehydration or low blood pressure, carefully administered intravenous fluids help restore kidney perfusion and improve filtration. However, in patients with fluid overload due to reduced urine output, excess fluid can cause complications such as pulmonary edema and hypertension. Therefore, close monitoring of input and output, body weight, and signs of fluid retention ensures optimal fluid balance and reduces strain on the kidneys.

Electrolyte and metabolic monitoring

This is significant because damaged kidneys cannot control electrolytes or keep acid-base balance. For example, elevated potassium levels (hyperkalemia) can cause life-threatening ventricular rhythms. Regular blood tests enable the early discovery and repair of these anomalies, avoiding difficulties while kidney function recovers.

Dietary management

In acute kidney injury, waste products build-up in the blood. Moderating protein intake can reduce urea production while still providing adequate nutrition. Controlling intake of sodium, potassium and phosphate helps to prevent dangerous electrolyte imbalances. Adequate caloric intake is important to prevent muscle breakdown, which would otherwise increase metabolic waste and burden the kidneys further.

Avoiding nephrotoxic drugs

This is essential to prevent additional kidney injury. Certain medications (such as NSAIDs, some antibiotics, and contrast agents used in imaging) and toxins can worsen kidney damage. Stopping or adjusting the dose of these drugs can protect kidney function and support recovery.

Pharmacological Management

Pharmacological treatment in acute kidney injury is mainly supportive and aimed at managing complications. Acute kidney injury medications are:

Management of hyperkalemia

In acute kidney injury, impaired potassium excretion can lead to dangerous hyperkalemia. Intravenous calcium gluconate protects the heart by stabilising cardiac membranes, while insulin (± beta-agonists) shifts potassium into cells to temporarily lower serum levels. Loop diuretics or dialysis help to remove excess potassium from the body. Together, these measures prevent life-threatening cardiac complications.

Fluid overload:  Reduced urine output can cause fluid accumulation and pulmonary edema. Intravenous loop diuretics can increase sodium and water excretion, hence help to reduce excess fluid and relieve respiratory and cardiovascular strain, thereby stabilizing the patient.

Metabolic acidosis:  When kidney function declines, acid accumulates in the body. Intravenous sodium bicarbonate helps to buffer excess hydrogen ions in severe acidosis, increasing blood pH and promoting cardiovascular stability until renal function recovers or dialysis is started.

Specific cause-based treatment

• Glomerulonephritis: If AKI is caused by immune-related glomerular inflammation, steroids or other immunosuppressants can lower immune activity and kidney inflammation. This helps prevent more damage and supports the kidneys in recovering their filtering ability.
• Rhabdomyolysis: In rhabdomyolysis, muscle breakdown produces a substance called myoglobin, which can harm renal tubules. Aggressive intravenous fluid therapy dilutes nephrotoxic chemicals and maintains renal perfusion, minimising tubular blockage and preventing increasing kidney injury.
• Sepsis: Sepsis can lead to AKI by causing widespread inflammation and lowering blood flow to the kidneys. Administering IV broad-spectrum antibiotics helps to treat the infection, and supportive care helps restore circulation to prevent kidney damage.
• Hypertension: Uncontrolled hypertension can worsen kidney injury by increasing intraglomerular pressure. Carefully dose-adjusted calcium channel blockers or beta blockers help control blood pressure, reducing additional stress on the kidneys during recovery.

Procedural Management

Procedural management focuses on monitoring and supportive interventions. This includes: 

Renal Replacement Therapy (RRT)

This is used in severe acute kidney injury when the kidneys cannot adequately remove waste products, excess fluid, or correct electrolyte and acid–base imbalances. It does not cure AKI but temporarily replaces kidney function while recovery occurs. This includes:

• Hemodialysis: This removes waste products, excess potassium, and excess fluid directly from the blood through a dialysis machine. It is especially useful in life-threatening complications such as severe hyperkalemia, metabolic acidosis, fluid overload, or uremic symptoms.
• Continuous Renal Replacement Therapy (CRRT): This is a slower, continuous form of dialysis generally used in critically ill or hemodynamically unstable patients. It removes fluid and toxins over 24 hours, which minimises sudden blood pressure changes and maintains stable circulation.

Urinary Catheterization

This helps to relieve bladder outlet obstruction, which may be a cause of post-renal AKI. By allowing urine to drain freely, it reduces back pressure on the kidneys and helps restore kidney function. Also, it enables accurate monitoring of urine output, which is important for assessing kidney function and guiding fluid management.

Surgical Management

Surgical management is required mainly in post-renal AKI, where there is urinary tract obstruction. Surgeries are:

Relief of obstruction
Post-renal acute kidney injury occurs when urine flow is blocked, causing back pressure that reduces glomerular filtration and damages kidney tissue. Surgical procedures like:

• Ureteric stenting: A ureteric stent is inserted into the ureter to bypass an obstruction (such as a stone or tumor) and allow urine to flow from the kidney to the bladder. By relieving the blockage, it decreases back pressure on the kidney, improves filtration, and prevents further damage.
• Percutaneous nephrostomy: A catheter is inserted directly into the renal pelvis through the skin to drain urine externally. It is often used when ureteric stenting is not possible. By immediately decompressing the kidney reduces pressure buildup and helps restore renal function.

Surgery for underlying causes

• Prostatic enlargement: An enlarged prostate can obstruct urine flow at the bladder outlet, causing bilateral hydronephrosis(swelling of a kidney) and acute kidney injury. Transurethral prostate excision is a surgical treatment that removes extra prostatic tissue, relieves blockage, and restores normal urine drainage, allowing kidney function to improve.
• Tumors: Tumors in the urinary tract or surrounding structures may compress or invade the ureters, causing obstruction. Surgical removal of the tumour relieves the blockage and restores urine flow.
• Renal stones causing obstruction: Large or impacted stones can block the ureter and cause acute obstructive AKI. Surgical removal, like lithotripsy or ureteroscopy, treats obstruction, relieves back pressure, and enables recovery of renal function.
  

Acute Kidney Injury Prognosis

The prognosis of acute kidney injury varies depending on the underlying cause, severity of kidney damage, patient’s age, comorbid conditions, and how quickly treatment is initiated.

• In many cases, particularly when AKI is mild and caused by reversible factors, kidney function can return completely to baseline within days to weeks after proper treatment.
• In more severe or prolonged cases, particularly when there is intrinsic renal damage, recovery can be incomplete. Some patients regain kidney function but are left with reduced glomerular filtration rate, increasing their likelihood of developing chronic kidney disease (CKD) later on. 
• Severe AKI may lead to permanent nephron loss and progression to CKD or even end-stage renal disease requiring long-term dialysis.
• AKI is also linked to an increase in mortality, particularly in older patients, severely ill people, those with sepsis or multi-organ failure, and patients requiring renal replacement treatment. Continuous oliguria or anuria, delayed treatment, pre-existing kidney disease, and significant comorbidities worsen the prognosis. 
• Even after apparent recovery, patients who have experienced AKI remain at higher risk for recurrent acute kidney injury, hypertension, and long-term kidney dysfunction, which require ongoing follow-up and monitoring of renal function.

The cost of Acute Kidney Injury (AKI) treatment in Hyderabad generally ranges from ₹70,000 to ₹9,00,000 and above (approx. US $845 – US $10,840).

The exact cost of AKI treatment varies depending on the severity of kidney injury, underlying cause (infection, dehydration, sepsis, drug toxicity, or major illness), need for ICU admission, dialysis requirement, and duration of hospital stay. Additional factors such as laboratory monitoring, imaging studies, medications, fluid and electrolyte management, and multi-organ support may also influence the total cost. Availability of cashless treatment options, TPA corporate tie-ups, and insurance assistance wherever applicable may further impact the overall expenses.

Cost Breakdown According to Type of Acute Kidney Injury Treatment

• Mild AKI With Medical Management & Monitoring – ₹70,000 – ₹2,00,000 (US $845 – US $2,410) 
• AKI Requiring Hospital Admission & IV Therapy – ₹1,20,000 – ₹3,50,000 (US $1,445 – US $4,210) 
• AKI With Hemodialysis Support – ₹2,00,000 – ₹6,00,000 (US $2,410 – US $7,230) 
• Severe AKI With ICU Care & CRRT (Continuous Dialysis) – ₹3,50,000 – ₹8,00,000 (US $4,210 – US $9,640) 
• AKI With Multi-Organ Failure & Prolonged ICU Stay – ₹5,00,000 – ₹9,00,000+ (US $6,020 – US $10,840+)

Frequently Asked Questions (FAQs) on Acute Kidney Injury (AKI)

Does kidney size increase in acute kidney injury?

Yes, in some cases of acute kidney injury, the kidneys may become slightly swollen due to inflammation, tissue edema or blockage. This can make them appear a little larger on an ultrasound scan. However, this does not happen in all cases. The change in size is usually mild and temporary. In contrast, in long-term (chronic) kidney disease, the kidneys often become smaller over time.

How is AKI defined clinically?

Acute kidney injury (AKI) is described as a sudden reduction in kidney function that lasts hours or days. Acute kidney injury (AKI) is diagnosed when blood creatinine levels rise rapidly, urine production decreases, or both. According to commonly used criteria (KDIGO guidelines), AKI is present if there is:

• Serum creatinine increases by 0.3 mg/dL or more within 48 hours, or
• Serum creatinine increases to 1.5 times or more from baseline within 7 days, or
• Urine output is less than 0.5 mL/kg/hour for 6 hours or more.
  

These criteria help doctors stage AKI into mild, moderate, or severe categories.

What laboratory findings suggest AKI?

When is dialysis indicated in acute kidney injury?

Dialysis is indicated in acute kidney injury (AKI) when life-threatening complications develop and do not respond to medical treatment. These indications are summarised by the mnemonic AEIOU: severe metabolic acidosis, dangerous electrolyte imbalance (especially hyperkalemia), certain intoxications, refractory fluid overload, and symptomatic uremia (such as confusion, pericarditis, or bleeding). In AKI, dialysis is usually temporary and supports the patient until kidney function recovers.

What is the role of biomarkers in AKI?

Biomarkers play an important role in the early detection, diagnosis, and prognosis of acute kidney injury. Traditional markers like serum creatinine tend to rise late, often only after significant kidney damage has already occurred. Whereas new biomarkers can detect kidney injury much earlier. These markers aid in the identification of high-risk individuals, allowing for earlier intervention and predicting damage severity, the requirement for dialysis, and overall prognosis. Commonly evaluated biomarkers include neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), cystatin C, and interleukin-18 (IL-18), which indicate tubular injury or reduced kidney function.

What is ICU-associated AKI?

ICU-associated acute kidney injury refers to kidney damage that develops in patients who are critically ill and are admitted to the intensive care unit (ICU). It is very common in ICU patients because they are severely sick with conditions like sepsis (severe infection), shock, major surgery, trauma, or heart failure. Low blood pressure, reduced blood flow to the kidneys, use of strong medications, and multi-organ failure can all contribute to it. ICU-associated AKI is more severe than AKI in general wards and is linked with higher complications and mortality.

How does AKI affect drug dosing?

When someone has AKI, the kidneys cannot remove drugs from the body efficiently. Many medications are cleared (filtered out) by the kidneys. If kidney function drops, these drugs can build up in the blood and cause side effects or toxicity.

Because of this, doctors often:

• Reduce the dose of certain medicines
• Increase the time between doses
• Avoid some drugs completely
• Closely monitor drug levels (for example, antibiotics)

What causes acute kidney injury in pregnancy?

AKI during pregnancy can be caused by severe hemorrhage, preeclampsia, eclampsia, HELLP syndrome, severe sepsis, septic abortion, or considerable dehydration. These disorders can limit blood flow to the kidneys or directly harm renal tissue. Early diagnosis and prompt medical management are crucial to protect both maternal and fetal health.

How is hyperkalemia treated in AKI?

Is Acute Kidney Injury Treatment Covered by Insurance at PACE Hospitals?

Yes, acute kidney injury treatment is generally covered under most health insurance policies at PACE Hospitals, subject to policy terms and approval. Since AKI often requires hospitalisation, dialysis, and ICU care, it is typically included under private insurance and corporate health plans.

At PACE Hospitals, patients can benefit from:

• Cashless hospitalization facilities with empaneled insurance providers
• Assistance from a dedicated insurance and TPA coordination team
• Pre-authorization support and documentation guidance
• Transparent cost estimates before admission
• Support for government health schemes where applicable
  
  

Coverage depends on dialysis coverage clauses, ICU limits, sum insured caps, waiting periods, and policy inclusions. Patients are encouraged to share insurance details in advance so the hospital’s insurance desk can verify eligibility and streamline approvals.