Honesty, I thought this was already the case, but I think they just got around to finding out it's metabolites and determining how to detect it. From Suppversity:
I can't find the study because it appears to be ahead of print.Scientists develop test to detect SARM LGD-4033 in your urine, bros
In the latest edition of "Drug Testing and Analysis", scientists from the Sports Medicine Research and Testing Laboratory in Salt Lake City present the first test for the selective androgen modulator (SARM) that has become increasingly popular among both pro- and hobby athletes.
SuppVersity - Nutrition and Exercise Science for Everyone | Cox, H. D., and Eichner, D. (2016) Detection of LGD-4033 and its metabolites in athlete urine samples. Drug Test. Analysis, doi: 10.1002/dta.1986.