Hi Shirley – I agree with you in general. If a patient is told their Free T4 is 2.2, that is completely useless information unless it is accompanied by the specific reference range used by that lab. And having two patients who use two different labs try to compare their lab results will be an “apples to oranges” comparison unless the labs use the exact same ranges.
However, there are some instances where labs have not kept pace with the latest medical research, in particular, with the upper end of the “normal” range for TSH and also in terms of trimester-specific TSH and T4 guidelines for women who are pregnant. Until the various laboratories catch up with these latest recommendations, it’s important for doctors and patients to be aware of the discrepancy in order to ensure optimal treatment.
Here’s an interview with a physician from the Boston University School of Medicine that talks about some of the controversy and special cases. Also, for those who are interested in trimester-specific TSH and T4 ranges for pregnancy, included below is a link to the American Thyroid Association’s guidelines on pregnancy. Of course, the guidance says to use the lab’s own range first – *if* trimester-specific ranges are available.(Note on links: if you click directly on the following links, you will need to use your browser's “back” button to return to the boards after viewing, or you will have to log back in to the forum. As an alternative, you can right-click the link and open it in a new tab or new window).
Pregnancy Guidelines: http://thyroidguidelines.net/sites/thyroidguidelines.net/files/file/thy.2011.0087.pdf