From the Guidelines
The primary difference between acute and subacute kidney injury lies in their management and treatment approaches, with acute kidney injury requiring immediate intervention and subacute kidney injury allowing for a more measured approach. The management of acute kidney injury (AKI) and subacute kidney injury differs significantly in terms of urgency and strategy. AKI, as defined by the KDIGO guideline, is an abrupt decrease in kidney function occurring over 7 days or less 1, and its management involves immediate intervention with fluid resuscitation, correction of electrolyte imbalances, and prompt discontinuation of nephrotoxic medications, as outlined in the KDIGO AKI guideline recommendations 1. In contrast, subacute kidney injury, which develops over days to weeks, allows for a more gradual approach with fluid optimization, careful medication adjustment, and time for diagnostic workup before considering renal replacement therapy.
Some key considerations for managing AKI and subacute kidney injury include:
- Discontinuing all nephrotoxic agents when possible, which is moderately relevant to subacute kidney disease (AKD) with or without AKI 1
- Ensuring volume status and perfusion pressure, which is moderately relevant, especially in cases like cardiorenal syndrome 1
- Monitoring serum creatinine and urine output, although the relevance of urine output monitoring is mixed 1
- Considering alternatives to radiocontrast, which is moderately relevant 1
- Checking for changes in drug dosing, which is highly relevant 1
The distinction between AKI and subacute kidney injury is crucial because the rapid deterioration in AKI can be life-threatening within hours, requiring emergency protocols, while subacute injury provides a window for more comprehensive evaluation and targeted interventions before irreversible damage occurs. According to the Acute Disease Quality Initiative (ADQI) consensus statement, AKI is associated with significant morbidity and mortality, and survivors are at increased risk of developing chronic kidney disease (CKD) and end-stage renal disease (ESRD) 1. Therefore, identifying and treating the underlying causes of both AKI and subacute kidney injury, while preventing immediate harm in AKI and progression to CKD in subacute cases, is essential for improving patient outcomes.
From the Research
Definition and Classification of Acute Kidney Injury
- Acute kidney injury (AKI) is characterized by a sudden loss of excretory kidney function, manifested by an increase in serum creatinine level with or without reduced urine output 2, 3.
- The spectrum of injury ranges from mild to advanced, sometimes requiring renal replacement therapy 2.
- AKI is classified according to urine output and elevations in creatinine level, with etiologies categorized as prerenal, intrinsic renal, and postrenal 3, 4.
Management and Treatment of Acute Kidney Injury
- Management of AKI involves fluid resuscitation, avoidance of nephrotoxic medications and contrast media exposure, and correction of electrolyte imbalances 2, 4.
- General management principles include determination of volume status, fluid resuscitation with isotonic crystalloid, treatment of volume overload with diuretics, and adjustment of prescribed drugs according to renal function 3.
- Renal replacement therapy (dialysis) is indicated for refractory hyperkalemia, volume overload, intractable acidosis, and uremic encephalopathy, pericarditis, or pleuritis 2, 5.
Subacute Kidney Injury
- There is limited information available on subacute kidney injury, and it is not clearly defined in the provided studies.
- However, it is mentioned that acute kidney disease and disorders (AKD) can lead to chronic kidney disease (CKD), and that slow deterioration of kidney function or persistent kidney dysfunction is associated with an irreversible loss of kidney cells and nephrons 6.
Comparison of Acute and Subacute Kidney Injury
- Acute kidney injury is a clinical syndrome characterized by a rapid decline in glomerular filtration rate, whereas subacute kidney injury is not clearly defined 3, 6.
- Management and treatment of AKI focus on addressing the underlying causes, limiting damage, and preventing progression, whereas the management of subacute kidney injury is not specified in the provided studies 2, 4.