A physician asks your laboratory to begin performing thyroid…
A physician asks your laboratory to begin performing thyroid-stimulating hormone (TSH) analyses on all specimens that have a free thyroxine (FT4) analysis ordered, a practice that your laboratory currently does not perform. Your laboratory typically performs TSH only on those FT4 specimens that are outside the population-based reference interval. The physician suggests using subject-based reference intervals, claiming that population-based intervals are clinically insensitive. What is the basis of this claim?