Serum Cholinesterase test is a test conducted to determine the levels of acetylcholinesterase and pseudocholinesterase in the blood. These two substances are responsible to help the nervous system work efficiently. They are also referred as neurotransmitters. These elements help nerves to send signals. For instance, when a muscle contraction is triggered by acetylcholinesterase at a neuromuscular junction, a cholinesterase is released to break down the former into choline and acetic acid so that the contracted muscle can be relaxed, rather than remaining the tensed state. Acetylcholinesterase is found in the nerve tissue and red blood corpuscles while the pseudocholinesterase element if primarily found in the liver.