Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (813 page)

   Other factors that may also increase cholesterol include cigarette smoking, age, hypertension, family history of premature heart disease, preexisting heart disease, and DM.

Suggested Reading

American Heart Association. Cholesterol.
http://www.heart.org/HEARTORG/Conditions/Cholesterol/CholestrolATH_UCM_001089_SubHomePage.jsp
. Accessed November 18, 2010.

CHOLINESTERASE (PSEUDOCHOLINESTERASE) AND DIBUCAINE INHIBITION

   Definition

   Cholinesterase is an enzyme that catalyzes the hydrolysis of the neurotransmitter Ach into choline and acetic acid, a reaction necessary to allow a cholinergic neuron to return to its resting state after activation.

   Serum cholinesterase, often called pseudocholinesterase or PChE, is distinguished from acetylcholinesterase (AChE or “true cholinesterase”) by both location and substrate.

   PChE is found primarily in the liver.

   AChE, also known as RBC cholinesterase, erythrocyte cholinesterase, or Ach acetylhydrolase, is found primarily in the blood and neural synapses.

   The difference between the two types of cholinesterase has to do with their respective preferences for substrates: AChE hydrolyzes Ach more quickly, and PChE hydrolyzes butyrylcholine more quickly.

   Phenotype interpretation is based on the total PChE activity and the percent of inhibition caused by dibucaine. Although there are >25 different phenotypes, most are extremely rare. Patients with unusual phenotypes cannot metabolize succinylcholine or mivacurium in the normal fashion; therefore, these patients can have prolonged paralysis following the use of these drugs.

   Other names: choline esterase II, SChE, Ach acylhydrolase, butyrylcholinesterase (BChE), dibucaine inhibition, and plasma cholinesterase.

   
Normal range:

   Pseudocholinesterase, total: 2,900–7,100 U/L

   Dibucaine inhibition: 70–90% (congenital deficiency 18–20%)