Insurers are planning or considering fleeing the Obamacare exchange in Iowa, a move that is driven by an overly sick, costly risk pool that includes a patient whose medical bills total $1 million a month.

The patient, a teenage boy, faces a devastating illness that likely requires weekly or daily infusions. Known as hemophilia, the life-threatening disorder prevents blood from clotting, which can lead to internal bleeding, joint damage or infections.