what was the name of the lab test that patient 3125 first recieved on this hospital visit?
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 = 3125 and admissions.dischtime is null ) order by labevents.charttime asc limit 1 )