specimen requirements and normal levels

• Specimen for urea: serum, plasma, or urine; does not need to be fasting 
• Specimen for urea: If using plasma, cannot use sodium citrate or sodium fluoride; will probably be heparinized plasma
• specimen for urea: Should be analyzed within 2-3 hours of collection or refrigerated 
• urea on body fluids: no established values
• • Normal ranges of urea: adult serum or plasma is 6-20 mg/dL; 24 hour urine - 12-20 grams per day