In 2022, Emily Shults, then 47, had recently moved to Magnolia, Texas, from California, to be closer to family. During the move, she remembers dealing with bad back pain. Emily wasn’t too concerned. “I thought I’d tweaked something in the move,” she says.

But she went to a local doctor north of Houston to get checked out.

Blood work showed she was borderline anemic. She was referred to...