Core Laboratory Procedures Flashcards

A laboratory has received a request for a blood ammonia level. To ensure pre-analytical integrity, which of the following handling procedures is required immediately after collection?

Answer: Place the specimen in an ice slurry and transport it to the lab immediately.

Ammonia levels in a blood specimen can increase rapidly at room temperature due to metabolic processes within the red blood cells. Chilling the sample in an ice slurry immediately after collection significantly slows this process, preserving the in-vivo concentration of ammonia until the sample can be centrifuged and analyzed.

An MLA/T is creating an aliquot from a primary serum tube for send-out testing. According to CLSI standards, what is the minimum information that must be included on the label of the new aliquot tube?

Answer: At least two unique patient identifiers (e.g., full name and DOB).

To ensure patient safety and prevent misidentification errors, all specimen containers, including secondary aliquot tubes, must be labeled with at least two unique patient identifiers. Common identifiers include the patient's full name, date of birth (DOB), or a unique medical record number (MRN). This is a critical requirement from accreditation bodies and standards organizations like CLSI.

A quality control check on a patient's hemoglobin result flags a 'delta check' failure, showing a result of 85 g/L today compared to 140 g/L yesterday. Which of the following is the MOST likely pre-analytical cause for this discrepancy?

Answer: The sample was drawn from an arm with a running IV infusion.

A significant, unexpected drop in hemoglobin suggests hemodilution. Drawing a blood sample from a site proximal to a running IV line can cause the sample to be diluted with the IV fluid, leading to falsely decreased results for many analytes, including a complete blood count. This is a common pre-analytical error that delta checks are designed to help detect.

An MLA/T is organizing the chemical storage cabinet. Which of the following represents an unsafe storage practice that must be corrected immediately?

Answer: Placing bottles of concentrated hydrochloric acid and sodium hydroxide on the same shelf.

Strong acids (like hydrochloric acid) and strong bases (like sodium hydroxide) are incompatible and can react violently if they mix, generating significant heat and hazardous fumes. They must be stored separately, ideally in different cabinets or at least in separate, spill-proof secondary containers.

Excessive centrifugation speed or time is most likely to cause mechanical hemolysis, leading to a falsely elevated result for which of the following analytes?

Answer: Potassium

Red blood cells contain a much higher concentration of potassium than blood plasma. When red cells are ruptured (hemolysis) by excessive mechanical force during centrifugation, this intracellular potassium is released into the serum or plasma, causing a significant and false elevation in the measured potassium level.

An MLA/T is performing daily quality control (QC) on a point-of-care glucose meter. In addition to the daily requirement, in which of the following situations is it also mandatory to run QC?

Answer: When a new vial of test strips is opened.

Quality control must be performed on a point-of-care device not only on a scheduled basis (e.g., daily) but also whenever a new lot of reagents or supplies is introduced. Opening a new vial of test strips constitutes a change in reagents, and running QC verifies that the new strips are performing correctly with the meter. QC is also required if a device is dropped or if patient results are clinically unexpected.