Clsi Ep28 Now

The root cause analysis landed on Aliyah’s desk. She stared at the EP28 document, the same dog-eared copy she’d used for twenty years. And then she read the section she’d always skimmed:

The conflict tore the lab apart. Clinicians started calling. A healthy medical student with a TSH of 3.8—perfectly fine by the old book—was now flagged high. An exhausted intern with a TSH of 0.5 was flagged low, even though she felt fine after a night shift. clsi ep28

Mrs. Eleanor Park, 68, came in for fatigue. Her TSH was 3.9 mIU/L—within the manufacturer’s range but above Aliyah’s verified upper limit of 3.2. Using the lab’s new narrow interval, the computer flagged it as Abnormal-High . The junior resident started her on low-dose levothyroxine. The root cause analysis landed on Aliyah’s desk

Then came the case that changed everything. Clinicians started calling

“Reference intervals may need to be partitioned by age, sex, or other factors… especially for analytes like TSH, where values increase with age.”

Aliyah nodded. “But EP28 says if we have 120 subjects, nonparametric ranking is the gold standard. The 2.5th and 97.5th percentiles are 0.6 and 3.2. That’s our truth.”