specimen requirements, interferences, normal values

• specimen requirements for ammonia: must be plasma (either heparin or EDTA)
• plasma for ammonia must be placed on ice immediately after drawing, as amino acids will spontaneously deaminate in vitro, keeping it cool slows down deamination
• plasma for ammonia should be spun within 20 minutes of drawing
• hemolysis for ammonia specimens should be avoided, as RBCs have 2-3x levels of ammonia than plasma
• for ammonia, lab should be sequestered or protected from environmental factors - tobacco smoke, detergents (anything that has ammonia in cleanser), certain drugs (see increase with barbituates, diuretics, ethanol, and narcotic analgesics)
• ammonia levels will be decreased with certain antibiotics, levodopa, diphahydramine, and lactobacillus acidophilius 
• reference levels

  A) 19-60 micrograms/dL