**6. Laboratory**

The laboratory tests are of little importance to diagnose a snakebite, with the exception of the ELISA test, which is available to identify the species involved, based on venom antigens. These studies are expensive and are not fully available and are of no value except for epidemiological studies. In a hospital setting , laboratory studies are important to monitor poisoning victims, as well as when determining stages of treatment.

Changes in the blood include anemia, leukocytosis and thrombocytopenia, the blood smear may show evidence of hemolysis. Also, prolonged clotting times and decreased fibrinogen may be present. Among the metabolic changes we can find hypokalemia and respiratory acidosis if neuroparalysis occurs.

Urinalysis may reveal hematuria, proteinuria and hemoglobinuria. Electrocardiographic changes are usually nonspecific and may include rhythm disturbances, mainly bradycardia, AV block with ST segment elevation or depression. Cholesterol lowering has been documented and can be explained by transcapillary lipoprotein loss. There have been reports of changes in the electroencephalogram in up to 96% of patients with snake bites, but none showed clinical changes or encephalopathy. In 62% of the patients, the electroencephalogram showed grade I changes, 31% showed grade II changes. (Avila-Aguero: ML199).
