Cholinesterase (ChE) Test Using Ellman’s Photometric Method

Abstract

Cholinesterase (ChE) is a group of enzymes that hydrolyze cholinester. There are two ChE isoenzymes in the blood, namely Acetylcholinesterase (AChE) and Butyrylcholinesterase (BChE). Both ChE isoenzymes are required in the process of sending nerve signals. The activity of these two ChE isoenzymes will be decreased by exposure to toxic chemical agents, insecticides such as organophosphates or carbamates, anesthetic agents, and drug therapy for Alzheimer’s disease (Donepezil or Rivastigmine). Therefore, AChE and BChE are potential biomarkers of suppression and increased activity of the central and peripheral nervous systems. In addition, measurement of serum ChE enzyme activity helps assess liver function, among other parameters. ChE enzyme activity can be measured by decreasing substrate concentration or increasing product concentration. Many methods have been developed to measure the activity of ChE as an enzyme. However, of these methods, the most popular and the gold standard is the photometric method based on increasing the concentration of Thiocholine, which is also known as Ellman’s photometric method. ChE enzyme activity was measured according to the increase in yellow color production using a photometer using endpoint methods at a wavelength (λ) of 412 nm. ChE is slightly increased in diseases: thyrotoxicosis, schizophrenia, hypertension, acute emotional disturbances, and increases 2-3 times the normal value in nephrotic syndrome. Serum ChE is decreased in impaired hepatic synthesis, chronic liver disease, hypoalbumin, and after the use of anticholinesterase drugs. In acute and chronic hepatitis, ChE decreases by about 30%-50%. A decrease in ChE of 50%-70% can be seen in cirrhosis and carcinoma that metastasizes to the liver.