You see, itâs actually the distance from the subject. The focal length is an indicator of the distance from the subject: the images are all framed the same; differences arise because the focal length is getting longer (zooming in) as the camera moves further away from the subject.
Normal values range from 0.4 to 4.0 milli-international units per liter (mIU/L). 1  TSH values can vary during the day. It is best to have the test early in the morning.  Experts do not fully agree on what the upper number should be. Opinions vary from 2.5 to 4.0 mIU/L.
People frequently write to ask about why they have different TSH levels from blood test to blood test. For example, a TSH test three months ago may have showed a TSH level of 3.0, but the most recent test this week shows 1.1. Or perhaps a year ago, the TSH was 0.5, and now it's 5.0.