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

What is a fasting urine specimen?

1. The first voided urine specimen of the day

2. The second voided urine specimen of the day

3. A 24-hour collected urine specimen

4. A specimen collected after a full meal

The correct answer is: The second voided urine specimen of the day

A fasting urine specimen is the urine collected after a period of fasting, which means no food has been consumed, typically for at least eight hours. The key aspect of a fasting urine specimen is that it often refers to the first voided urine of the day after this fasting period. This is significant because it tends to provide a more concentrated sample that can yield more accurate results for certain analyses, particularly those measuring substances that fluctuate based on diet or metabolism. In laboratory practice, the first morning urine is preferred because it reflects the body’s state after fasting overnight and can provide insights into hydration levels, renal function, and metabolic processes. A fasting urine specimen may help in assessing conditions like diabetes mellitus or evaluating kidney function, where concentrated substances are critical for diagnosis. Knowing that the first voided urine after fasting provides a clearer picture helps in understanding why this particular specimen type is essential in clinical testing.