Evaluation of the 13C-methacetin breath test for quantitative liver function testing

Area of Science:

• Hepatology
• Diagnostic Medicine
• Biochemistry

Background:

• Noninvasive 13C-breath tests are crucial for evaluating hepatocellular dysfunction.
• 13C-methacetin undergoes hepatic O-demethylation to produce 13CO2 and acetaminophen, serving as a metabolic marker.
• Assessing liver function quantitatively is vital for managing liver diseases.

Purpose of the Study:

• To evaluate the diagnostic performance of the 13C-methacetin breath test.
• To compare its efficacy against established liver function tests like the Child-Pugh score, MEGX-test, and indocyanine green clearance.
• To determine the test's ability to discriminate between cirrhotic and non-cirrhotic individuals.

Main Methods:

• Oral administration of 2 mg/kg 13C-methacetin to 31 liver cirrhosis patients and 10 healthy volunteers.
• Measurement of exhaled 13CO2 increase over baseline (delta over baseline, DOB) at 20 minutes post-administration.
• Statistical analysis comparing DOB values with Child-Pugh score, MEGX-test, and indocyanine green clearance.

Main Results:

• All breath test parameters effectively discriminated between cirrhotic and non-cirrhotic subjects.
• The 20-minute DOB value demonstrated a superior correlation (r=0.67) with the Child-Pugh score compared to MEGX-test (r=0.39) and indocyanine green clearance (r=0.43).
• A cut-off DOB of <= 25 delta /1000 at 20 minutes yielded 93.5% sensitivity and 95% specificity for detecting cirrhosis.

Conclusions:

• The 13C-methacetin breath test is a safe and precise quantitative liver function test.
• A single breath sample 20 minutes post-administration effectively differentiates cirrhotic from non-cirrhotic patients.
• Further research is needed to establish the prognostic value of this breath test.