1 Leaf shutters are usually fitted within a lens assembly (central shutter), or more rarely immediately behind (behind-the-lens shutter) or, even more rarely, in front of a lens, and shut off the beam of light where it is narrow. 2  Focal-plane shutters are mounted near the focal plane and move to uncover the film or sensor.
DHEA levels begin to naturally decline by the age of 30. While normal levels for women in their 20s fall between 65 and 380 Âµg/dL, for women in their 30s and 40s, the average normal range is 45 to 270 and 32 to 240 Âµg/dL, respectively.
Normal and Abnormal Test Results. Although various professional health bodies have specified the normal range for TSH to be 0.4 - 4.5 mIU/L in the past, new regulations recognize that this range is too wide. Currently, the standard reference range for TSH is 0.4 - 3.0 mIU/L. However, clinical data show that 95% of euthyroid patients fall in the range 0.4 - 2.5 mIU/L. In addition, adults with TSH levels over 2.0 mIU/L are likely to develop hypothyroidism later in life. Therefore, the ideal range of TSH is 0.4 - 2.0 mIU/L. Children, generally, have higher TSH levels than adult. The National Academy of Clinical Biochemistry recommends 1.3 - 19 mUI/L for newborns. These values drop with age and by the first year, TSH level for an infant should be between 0.4 mIU/L and 7 mIU/L.