What is the relationship between snake bites and Acute Kidney Injury (AKI)?

From the Guidelines

Snake bites can cause Acute Kidney Injury (AKI) due to the venom's direct nephrotoxicity, hemolysis, rhabdomyolysis, disseminated intravascular coagulation, and hypotension, and prompt recognition and management are crucial to prevent morbidity and mortality. The relationship between snake bites and AKI is well-established, with certain snake venoms, such as those from vipers and some elapids, containing toxins that can directly damage the kidneys 1.

Pathophysiology and Clinical Presentation

The venom from crotaline snakes, which are responsible for more than 95% of venomous bites in North America, can cause tissue injury, low blood pressure, bleeding, and muscle fasciculations leading to paralysis 1. The clinical presentation of snake bite-induced AKI may include signs and symptoms such as hematuria, proteinuria, and elevated serum creatinine levels.

Management and Treatment

Management of snake bite-induced AKI begins with immediate first aid and rapid transport to a medical facility. Upon arrival, assessment should include vital signs, local wound examination, and laboratory tests including complete blood count, coagulation profile, renal function tests, electrolytes, creatine kinase, and urinalysis. Antivenom administration is the cornerstone of treatment and should be given as soon as possible, typically 4-10 vials initially for most species, with additional doses based on clinical response. Supportive care includes intravenous fluids, maintaining urine output above 0.5-1 ml/kg/hr, and correcting electrolyte imbalances.

Prognosis and Long-term Follow-up

Prognosis depends on the snake species, amount of venom injected, time to antivenom administration, and pre-existing comorbidities. Early intervention significantly improves outcomes, with most patients recovering renal function within weeks if properly managed 1. Long-term follow-up is recommended as some patients may develop chronic kidney disease following severe AKI episodes. Prevention of compartment syndrome through fasciotomy may be required in severe cases with significant local envenomation.

From the Research

Relationship Between Snake Bites and Acute Kidney Injury (AKI)

• Snake bites can cause Acute Kidney Injury (AKI) through multiple mechanisms, including enzymatic toxins in snake venom that result in injuries to all kidney cell types 2.
• The pathogenesis of kidney injury due to snake envenomation includes ischemia, proteolytic degradation of the glomerular basement membrane, deposition of microthrombi, direct cytotoxic action of venom, and systemic myotoxicity 2.
• Clinical features of AKI include fatigue, loss of appetite, headache, nausea, vomiting, oliguria, and anuria, and monitoring of blood pressure, fluid balance, and serum creatinine is useful in managing AKI induced by snake envenomation 2.

Long-Term Renal Outcomes

• Long-term follow-up of patients who developed AKI after snake bites shows that a significant percentage of patients continue to have features of persistent renal damage, with some progressing to end-stage renal disease (ESRD) 3.
• A study found that 41% of patients showed persistent renal involvement, and 5% progressed to ESRD, while 20% had a glomerular filtration rate (GFR) <45 mL/min 3.
• Another study found that 21.2% of patients developed AKI, and on follow-up, 49% of patients had normalized creatinine levels, and only 2 out of 16 patients had an elevated creatinine level 4.

Prognosis and Long-Term Outcomes

• Snakebite-related AKI is associated with considerable risk of mortality, and the greater the AKI stage, the greater the likelihood of mortality 5.
• A study found that 21.5% of patients with haemotoxic envenomation and AKI died, and mechanical ventilation, hypotension, and capillary leak syndrome were independent predictors of mortality 5.
• Long-term follow-up data showed that 28.7% of patients developed adverse renal outcomes, including chronic kidney disease, prehypertension, and hypertension 5.

Mechanisms and Management

• Coagulation abnormalities are usually present and contribute to AKI development, and a better comprehension of AKI pathogenesis may improve patient management 6.
• Early initiation of anti-snake venom and early diagnosis of AKI are desirable, and biomarkers such as urinary clusterin, urinary neutrophil gelatinase-associated lipocalin, and serum cystatin C may play an important clinical role in the future 2.
• Management of AKI induced by snake envenomation includes fluid and electrolyte management, and kidney support, including early and prompt initiation of kidney replacement therapy when indicated 2.