ATN lab findings,”Urine osm >350Urine Na >40FENa >1%Full brownish June 22, 2017 mfadmin Medicine Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review. ATN lab findings,”Urine osm >350Urine Na >40FENa >1%Full brownish granular casts with epithelial casts”