My understanding with sclc the only way it is measured is-limited or extensive. Limited meaning to one area and extensive is it has spread to other organs, ex. liver, adrenal gland, brain, etc. I was told by my oncologist that the LDH usually increases with the increase in the cancer. He gets an LDH with each regular bld work up. My LDH is always high but the only time it increased was when the sclc had spread to the L lung last Feb. Hope this helps some.