Snake Bite-Induced Acute Renal Failure

Snake bite-induced Acute Renal Failure occurs frequently in tropic areas, such as Saudi Arabia etc. Approximately 5 million cases of snake bite or scorpion sting etc. occurred all around the world; around 100,000 deaths result from animal venom in every single year.
Animal toxin is a complex of protein, peptides, enzyme together with some other chemical substances. Animal toxins cause cell damages through a variety of mechanisms in human body. As a metabolic organ rich in massive blood vessels, Kidneys get involved extremely easy. That's why animal toxins such as snake bite can easily trigger Acute Renal Failure. How does snake toxin work in human body?
▪ Direct toxicity. Enzyme (especially phospholipase A2 and proteases) works on epicyte and cause cell damage. Phospholipase A2 (catalyzed hydrolysis of phosphoric acid glycerides) can be divided into 3 categories according to its chemical structure:
1. Snake venom which is secreted by cobra family or hydrophis.
2. Snake venom which is secreted by viperidae or crotalidae.
3. Present as a form of calcium ion existing in bee venom (bee) or gila toxins (heloderma).
Phospholipase A2 induced cell damages manifest as hemolysis, rhabdomyolysis, endothelial cell necrosis, renal tubular damage and nerve damage.
Phospholipase A2 and proteases have an impact upon various levels of haemagglutination, and have a tendency to bleeding. Metalloproteinases cause cytoskeletal destruction, which leads to cellular damage, apoptosis and disintegration. Rattlesnake venom (trimeresurus) contains metalloproteinase which decreases activities of membrane and vascular endothelial cells, is responsible for cellular apoptosis. Putting Brazilian spearhead-cobra venom which contains metalloproteinase into renal cells of Madin-darby, it decomposes cytoskeleton as well as damages the conglutination between cell-stroma.
▪ Changes in hemodynamics. Hemodynamic changes can be caused by toxin or other factors. Hemodynamic changes become significantly, especially in toxins which are rich in enzyme (such as snake venom or bee venom). Both protease and phospholipase A2 can reduce bloodstream to kidneys. Atractaspis engaddensis contains endothelin receptor agonists; it works as a vasoconstrictor similar with endothelin. Bothrops jararaca lowers the blood pressure through restrain angiotensin-converting enzyme. Temporarily hypertension may occur after biting by poisonous snakes.
Snakes such as cobra and adder as well as colubridae can cause renal damages. A report regarding a group with 400 patients who were bitten by the above-mentioned snakes shows that the incidence of proteinuria reaches 4%. A small number of patients have symptoms of nephrotic syndromes. Gross hematuria and microscopic hematuria occur most common; diuresis becomes another symptom in clinic.
People bite by snakes that release myotoxin and hemolytic toxin often occur Acute Renal Failure. The incidence is 5%-29%. Time of onset can range from several hours to even 96 hours. People who have been bitten by oxyuranus may have hemolytic uremic syndrome. Snake bite-induced Acute Renal Failure normally lasts 2 to 3 weeks. Patients with persistent oliguria may accompany with acute interstitial nephritis, acute tubular necrosis or even acute renal cortical necrosis. Snake bite-induced Acute Renal Failure can usually fully recovered unless renal cortical necrosis occurred.
Old people, renal cortical necrosis or those with serious bleeding complications usually have poor prognosis.
Once Acute Renal Failure occurred, early renal replacement treatment should be taken, especially continuous bedside blood purification is the optimal choice. It’s also feasible to take hemodialysis or peritoneal dialysis for those without qualified conditions. The earlier the treatment is taken, the better the prognosis will be.