Can cannabis show up in a sickle cell blood test?

The test for sickle: Cell hemoglobin is an electrophoretic technique, or alternatively, a test based upon differential solubility/ppt. Drug screens use a completely different technology. The tests must be done separately, and have no effect, one on the other. If you're asking because you have sickle cell disease and have been smoking marijuana, i'd advise you stop the latter and follow your dr.'s advice for the former.

No: These tests are specific.Unless you are going for an employment physical, where you accept that a drug test is required, it will not be done in most locals without your written authorization. If they are looking for sickle cell, that's what they test for.