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.
A TSH test measures the amount of thyroid stimulating hormone (TSH) in your blood. TSH is produced by the pituitary gland and tells the thyroid gland to make and release the hormones thyroxine (T4) and triiodothyronine (T3). See also: 1  T3 test.  T4 test.