Drug overdose and poisoning

What is being analysed?

Drug overdose and poisoning are analysed to detect, quantify, and occasionally, monitor drugs that cause acute overdose symptoms. The results of emergency and overdose tests are mainly used for therapeutic purposes. In the case that the results are required for legal reasons, other specific legal procedures are performed (forensic), which are usually accompanied by specific maneuvers for obtaining, storing, and analyzing the sample.

A person can become intoxicated with a variety of drugs (sold with or without a prescription), drugs, and household products. Some common examples are:

Acetaminophen (paracetamol): ingredient in many over-the-counter drugs; can cause liver injury when taken in doses higher than recommended. Acetylsalicylic acid or salicylate (Aspirin®): at high doses can cause acid-base balance disorders. Drug monitoring: these are drugs used in the treatment of various diseases, such as heart disease or epilepsy.

Why is this analysis carried out?

The analysis is performed to detect, evaluate, and monitor an overdose. The drugs and other substances ingested or absorbed are metabolised in the liver in a characteristic way and, over time, are eliminated from the body, mainly through the urine.

The speed of their elimination depends on a number of factors, including age, sex, and weight; the fact of having ingested some food simultaneously or having an underlying disease can also influence. On the other hand, the development of toxicity depends on the type of substance absorbed or ingested. Some substances cause symptoms only if they are present at high concentrations or above therapeutic values.

When is this analysis done?

The analysis is performed when symptoms such as delirium, difficulty breathing, nausea, agitation, seizures, changes in heart rhythm, or an increase in temperature suggestive of being associated with a drug are present, at regular intervals to monitor a drug overdose.

What sample is required?

The determination is made from a sample of venous blood; sometimes a urine sample, more rarely exhaled air, very rarely saliva or other body fluid. Is any prior preparation necessary? No special preparation is needed for this test.

How are the results used?

The results of overdose tests are mainly used for therapeutic purposes. In the case that the results are required for legal reasons, other specific legal procedures are performed (forensic), which are usually accompanied by specific maneuvers for obtaining, storing, and analysing the sample.

What are the normal values?

Normal values vary depending on the type of substance analyzed. It is important that the doctor who requests the test interprets the results in the clinical context of the patient.

What does it mean to have altered values?

Although therapeutic and potentially toxic drug values are known, a person may present undesirable effects or have signs of overdosage at concentrations of drugs considered normal.