American Society for Clinical Pathology (ASCP) Histotechnician Certification Practice Exam

When is the trough value of a drug typically collected?

1. After the patient receives the drug

2. Before the patient receives the drug

3. During the peak effect of the drug

4. At random intervals throughout the day

The correct answer is: Before the patient receives the drug

The trough value of a drug is typically collected before the patient receives the drug. This timing is crucial because the trough level represents the lowest concentration of the drug in the patient's bloodstream, which occurs just before the next dose is administered. Measuring the trough allows healthcare providers to assess whether the drug is being maintained within the therapeutic range without risking toxicity or under-dosing. Collecting the trough value before administration ensures an accurate assessment of how much of the drug is present in the body at its lowest concentration. This information is vital for adjusting dosages if necessary and for monitoring the effectiveness of the treatment. In contrast, measuring at peak effects or random intervals may not provide a clear assessment of the drug concentration needed for effective therapeutic outcomes.