This study was performed in five EDs. Three were urban EDs with 30,000 to 45,000 annual visits, and two were suburban EDs with 15,000 to 25,000 annual visits. Each hospital has its own central laboratory which can test the same emergency chemistry tests, including liver panel (alkaline phosphatase, protein, albumin, total bilirubin, direct bilirubin, GOT, and GPT), renal panel (BUN, creatinine, calcium, and phosphorus), pancreas enzymes (amylase, lipase), electrolytes (sodium, potassium, chloride, total CO2), lipid panel (total cholesterol, triglyceride, LDL-cholesterol, HDL-cholesterol), and blood gases (pH, pO2, pCO2, and bicarbonate).