tell me the first lab test that was given to patient 13838 in 08/2102?
select d_labitems.label from d_labitems where d_labitems.itemid in ( select labevents.itemid from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 13838 ) and strftime('%y-%m',labevents.charttime) = '2102-08' order by labevents.charttime asc limit 1 )