Two years ago, an urgent call from my father: My mother, then 84, was ill. Gray skin, sunken eyes, confused. At the hospital, her blood tests showed abnormally high levels of calcium. She had calcium poisoning. Calcium poisoning? Six weeks prior, it turned out, the family doctor had instructed her to start taking calcium tablets . . . → Read More: How Doctors Think, by Jerome Groopman M.D.