The Paracetamol - Acetaminophen - Serum test measures the level of paracetamol, also known as acetaminophen, in your blood. This test is often used to determine if a person has taken a toxic amount of this common over-the-counter medication, which can be harmful to the liver in high doses. It's typically performed if a paracetamol overdose is suspected, and it can also be helpful in monitoring the effectiveness of treatment for paracetamol toxicity. Overdose of paracetamol can lead to liver damage, and early detection can help prevent serious complications.