I do not know of a test for depression but my pdoc does do labs to check vit d levels-she feels low vit d contributes ti depression. She also wants me have some other tests-because I am sooooo sensitive to med doses and changes. She wants me yry the new genesight test-basivally,I believe it checks DNA and they use some markers to see which classes of psych meds might be more effective for me/fewer side effects. I do not think it is used for all the meds out there- just certain groups. She says I can check but many mainstream ins plans cover part medicare is covering it etc. I am also complex because of several gi issues,so whn my tract slows down/Been tested it can take me 18-20 hrs to digest what takes you 2 hrs...so meds can hang around for longer time periods/I suddenly get the effect but it's tripled....anyway..