Since starting his blog, KevinMD, nearly 10 years ago, Dr. Kevin Pho has become a rock star among the health care set, one of the few doctors recognizable by first name only. A primary care doctor, Dr. Pho presides over a social media empire that includes his blog, now a highly coveted publishing place for doctors and patients, a lively Facebook page and a nonstop Twitter stream that has become must-follow fodder for the medical Digirati. Now he and Susan Gay, a medical publisher, have written a book to help doctors do nearly the same. In "Establishing, Managing and Protecting Your Online Reputation: A Social Media Guide for Physicians and Medical Practices," Dr. Pho and Ms. Gay offer highly organized key points, useful statistics and exuberant testimonials from doctors who have successfully leapt over the digital divide.