What type of blood test should i do to check why i have mood swings , 17 years old male ?

Please see your: physician for an evaluation to see if the mood swings are within normal realm or not. If not - a thyroid function test may be taken to ensure that this is not a cause. But often much of the diagnosis comes from taking a good history. Take care.

Several: Mood is affected by overall health. If you are having problems with your mood, get a thorough physical with appropriate lab testing.If you are anemic, or have a vitamin deficiency, or hormonal imbalance, especially thyroid dysfunction, then these can be corrected & your mood improved. If you have no abnormalities, then ask your doc if you should see a psychologist or psychiatrist. No drugs/ETOH.

A psych eval: Blood tests will not be a likely way to learn more about mood swings, but a good psych eval might. It may take a long time to answer a 'why' question if that ever becomes clear - but you can still get a handle on them and both lessen the frequency and intensity w/ both therapy and medications. Teen years normally include some of this, so have an eval. Best!