Final answer:
A phlebotomist should immediately report troponin T levels that are significantly higher than the reference range, specifically levels exceeding the 99th percentile of the upper reference limit that indicate potential acute cardiac events.
Step-by-step explanation:
A phlebotomist is tasked with identifying and reporting critical values of laboratory tests, such as troponin T levels. Troponin T is a protein found in cardiac muscle, and its levels in the blood can significantly increase when there is damage to the heart, such as a myocardial infarction (heart attack). A value of troponin T that is significantly higher than the reference range should be reported immediately to the healthcare provider, as it may indicate an acute cardiac event. Specific cutoff values may vary by institution, but troponin T levels exceeding the 99th percent of the upper reference limit, typically measured in nanograms per liter (ng/L), are generally considered critical and warrant immediate attention.