I smoked weed three days ago and have to get a routine blood test soon i'm 16 will it show in my test results and will they tell my parents if it does?

"Soon" 's unspecific: Depends on how much - how often in the past and when the test is. It might if the answers are one way and not if the other. Also depends on who they are and how your parents are connected. Don't do it if it's illegal since your future can really be impacted by a criminal record. It matters. I wish you well. But pledge to be careful.