52 Acetylcholinesterase of erythrocytes (AChE)
Erythrocyte acetylcholinesterase (AChE) is the same enzyme that breaks down acetylcholine at nerve synapses, but located on the membrane of red blood cells. Its function there is not fully understood; it is considered a marker of the integrity of the red cell membrane, and its activity changes as red cells age. Clinically it is most important as a marker of exposure to cholinesterase inhibitors: organophosphate and carbamate pesticides and nerve agents inhibit AChE in synapses and on red cells in parallel, so red cell AChE reflects the degree of inhibition in the nervous system better than plasma cholinesterase.
Interpretation
Because normal activity varies widely between people and methods, results are best compared with the person's own baseline value (for example in agricultural workers before the spraying season) or with the laboratory range. Red cell AChE recovers slowly, at the rate of new red cell production (about 1% per day), so it also reflects past exposure, whereas plasma butyrylcholinesterase recovers faster.
Clinical significance
Low activity
Organophosphate or carbamate poisoning, chronic occupational exposure to pesticides, nerve agents; also reported in some haematological conditions (for example paroxysmal nocturnal haemoglobinuria) and conditions with membrane damage.
High activity
Young red cell population (reticulocytosis after bleeding or haemolysis); changes have also been described in several inflammatory, metabolic and neurological diseases.
Acute organophosphate poisoning causes excess acetylcholine: small pupils, salivation, sweating, vomiting, diarrhoea, slow pulse, bronchial secretions, muscle twitching and weakness, and respiratory failure. It is an emergency treated with atropine, oxygen and supportive care.
after contact with or swallowing pesticides, especially with small pupils, heavy sweating and salivation, vomiting, muscle twitching, breathing difficulty or drowsiness.
References
- Eddleston M, Buckley NA, Eyer P, Dawson AH. Management of acute organophosphorus pesticide poisoning. Lancet. 2008;371(9612):597–607. doi:10.1016/S0140-6736(07)61202-1
- Saldanha C. Human erythrocyte acetylcholinesterase in health and disease. Molecules. 2017;22(9):1499. doi:10.3390/molecules22091499
This article is for general information and does not replace a consultation with a doctor. Laboratory results must be interpreted by a physician together with symptoms and other tests.
Published on 29 April 2024