This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Anaesthesia
The dibucaine number refers to 
Select and explain. 
A. Ach cholinesterase activity derangement, B. Potency of muscle relaxants, C. Potency of general anaesthetics, D. None
A: Ach cholinesterase activity derangement
Answer: A: Ach cholinesterase activity derangement 
Explanation: Dibucaine number: Dibucaine (a local anaesthetic) inhibits 80% of normal pseudocholinesterase and 205 of atypical (non-functional) pseudocholinesterase. Therefore normal dibucaine number is 70-80%. The dibucaine number is used to measure the activity of atypical pseudocholinesterase.(Refer: stoelting's pharmacology and physiology in anaesthetic practice, 5th edition, pg no.290,304)