What are the acute signs and symptoms of acute kidney injury (AKI)?

From the Guidelines

Acute kidney injury (AKI) is characterized by an abrupt decrease in kidney function over hours to days, with signs and symptoms including decreased urine output, fluid retention, shortness of breath, fatigue, confusion, nausea, vomiting, and loss of appetite, as well as laboratory findings such as elevated serum creatinine and blood urea nitrogen levels 1.

Clinical Presentation

The clinical presentation of AKI can vary, but common signs and symptoms include:

• Decreased urine output (oliguria) of less than 0.5 ml/kg/h
• Fluid retention leading to swelling (edema) in the legs, ankles, and around the eyes
• Shortness of breath due to fluid buildup in the lungs or acidosis
• Fatigue, confusion, nausea, vomiting, and loss of appetite
• Laboratory findings such as elevated serum creatinine levels, with an increase of 0.3 mg/dl within 48 hours, or an increase to 1.5 times baseline within 7 days 1

Diagnosis and Classification

AKI is classified into three stages based on the KDIGO guidelines, which consider the increase in serum creatinine levels and urine output 1. The diagnosis of AKI is based on the following criteria:

• Increase in serum creatinine by 0.3 mg/dl within 48 hours
• Increase in serum creatinine to 1.5 times baseline within 7 days
• Urine output less than 0.5 ml/kg/h

Importance of Early Recognition

Early recognition of AKI is crucial to prevent further kidney damage and improve patient outcomes. Prompt diagnosis and treatment of AKI can help reduce morbidity, mortality, and improve quality of life 1.

From the Research

Definition and Classification of Acute Kidney Injury (AKI)

• Acute kidney injury (AKI) is characterized by an abrupt decrease in renal function or the onset of frank renal failure 2.
• AKI is defined as an increase in the serum creatinine (SCr) level of 0.3 mg/dL or more within 48 hours, an SCr level increase of 1.5 times or more of the baseline level within 7 days, or a decrease in urine output to less than 0.5 mL/kg/hour for 6 hours 2.
• The etiology of AKI is conceptually classified into three general categories: prerenal, intrarenal, and postrenal 3, 4, 5.

Acute Signs and Symptoms of AKI

• AKI is characterized by a sudden decline in or loss of kidney function, leading to accumulation of urea and other chemicals in the blood 6, 3.
• The spectrum of injury ranges from mild to advanced, sometimes requiring renal replacement therapy 5.
• Clinical assessment of a patient with AKI involves a medical record review, thorough history and physical examination, urinary and blood tests, renal imaging, and, in some instances, renal biopsy 4, 5.

Diagnosis and Management of AKI

• The diagnostic evaluation can be used to classify acute kidney injury as prerenal, intrinsic renal, or postrenal 5.
• Management of AKI involves fluid resuscitation, avoidance of nephrotoxic medications and contrast media exposure, and correction of electrolyte imbalances 5.
• Renal replacement therapy (dialysis) is indicated for refractory hyperkalemia; volume overload; intractable acidosis; uremic encephalopathy, pericarditis, or pleuritis; and removal of certain toxins 5.