My friend is having a blood test. it checks for cbc, tsh and ft4. will marihuana and alcohol show up in these test results?

Unlikely, unless . .: If the doctor also orders a screen for specific drugs and alcohol level, these results would show up. If testing only for cbc, tsh, and free t4, they would not. If you're concerned about positive drug & alcohol testing, best to stay away from using those substances -- especially at age 15.

NO: The test you mention would not show drug or alcohol levels.