How would you approach microcytosis without anemia with high TSAT and ferritin?

This is likely thalassemia trait with iron overload. I would look at the smear to confirm, consider hemoglobin electrophoresis. Sometimes HFE mutations are cofactors that can add to the iron overload so I look for those.

If the ferritin is >300, I consider careful phlebotomy to assess mobilized iron...