Cholinesterase

Cholinesterase (ChE) refers mainly to serum pseudocholinesterase (butyrylcholinesterase), which is synthesized in the liver and circulates in plasma.

There are two types:

• True cholinesterase (Acetylcholinesterase) – found in RBCs and nerve tissue
• Pseudocholinesterase (Butyrylcholinesterase) – found in serum (clinically important)

1️⃣ Indicator of Liver Function

Since pseudocholinesterase is synthesized in the liver:

↓ Levels Seen In:

• Acute hepatitis
• Chronic liver disease
• Cirrhosis
• Liver failure

Metastatic liver disease

🔎 It reflects liver synthetic capacity, similar to albumin.

2️⃣ Organophosphate Poisoning (Very Important)

Organophosphate insecticides inhibit cholinesterase.

Markedly Decreased Levels In:

• Organophosphate poisoning
• Carbamate poisoning
• Clinical features:
• Excess acetylcholine
• Salivation
• Sweating
• Muscle twitching
• Respiratory distress

👉 Serum cholinesterase level helps:

• Diagnose poisoning
• Assess severity
• Monitor treatment response

3️⃣ Prolonged Apnea After Succinylcholine

Some individuals have atypical pseudocholinesterase.

• Cannot metabolize succinylcholine properly
• Leads to prolonged muscle paralysis after anesthesia

Test used:

Dibucaine inhibition test

4️⃣ Conditions with Increased Levels

May be increased in:

• Nephrotic syndrome
• Obesity
• Diabetes mellitus
• Hyperthyroidism

Clinical importance of increase is less significant than decrease.

Normal Reference Range :

Approximately 5,000 – 12,000 IU/L
(Varies with laboratory and method)