Practice Test Geeks(CLT) Clinical Laboratory Technologist Certification Practice Test
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Quality Control & Assurance in Testing Flashcards

7 cards from real CLT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Quality Control & Assurance in Testing flashcards as text

  1. A laboratory implements a delta check for sodium results. A patient's sodium has changed from 138 mEq/L to 155 mEq/L in 4 hours. The FIRST step is to:

    Answer: Verify patient identity and repeat the test

    When a delta check flag is triggered, verifying patient identity and repeating the test are the first steps to rule out mislabeling or analytical error.

  2. The reference interval for a test was established using 120 healthy individuals. Approximately how many values are expected to fall outside the reference interval?

    Answer: 6 values

    Reference intervals are typically set at the central 95%, so approximately 5% of healthy individuals fall outside; 5% of 120 = 6 values.

  3. A laboratory notices that QC precision has increased (wider SD) specifically after the instrument's daily maintenance cycle. This pattern MOST likely indicates:

    Answer: An instrument problem introduced by maintenance

    If precision worsens specifically after maintenance, the maintenance procedure itself may be introducing variability, such as improper component reinstallation.

  4. Which document specifies the criteria for acceptable performance in external proficiency testing in the United States?

    Answer: CLIA '88 regulations

    CLIA '88 regulations establish the performance criteria that laboratories must meet on proficiency testing surveys for regulated analytes.

  5. A laboratory method has a sensitivity of 95% and specificity of 90% for detecting a disease with 1% prevalence. What is the APPROXIMATE positive predictive value (PPV)?

    Answer: 8.7%

    At 1% prevalence with 95% sensitivity and 90% specificity, the PPV is approximately 8.7% due to the large number of false positives in a low-prevalence population.

  6. In a method comparison study, the slope of the regression line is 1.08 and the y-intercept is -2.0. What type of error does this PRIMARILY indicate?

    Answer: Both constant and proportional systematic errors

    A slope other than 1.0 indicates proportional error and a y-intercept other than 0 indicates constant error; both are present here.

  7. A laboratory is validating a new hematology analyzer. Carryover testing is performed by running three replicates of a high sample followed by three replicates of a low sample. This test evaluates:

    Answer: Contamination of a low sample by a preceding high sample

    Carryover testing assesses whether residual analyte from a high-concentration sample contaminates subsequent low-concentration samples.