About threeyears ago, Soumya Rangarajan struggled day after day with exhaustion, headaches, and heart palpitations. As a frontline hospital doctor during the Covid-19 pandemic, she first attributed her symptoms to the demands of an unprecedented health care crisis. But a social media post got Rangarajan thinking about the possibility that she might actually be the victim of something more mundane: an iron deficiency. She requested a blood test from her doctor and the results determined she had anemia, a condition caused by lower-than-normal levels of iron in the blood. It was the first step to…