Master Clinician: Dolores Shoback, MD
An Exquisite Balance
Endocrinologist Dolores Shoback, MD, has discovered many secrets of the parathyroid glands, four pea-sized organs in the neck. Small but mighty, they regulate the bloodstream's calcium balance by releasing parathyroid hormone (PTH), which stimulates bones to release calcium and kidneys to hoard it rather than releasing it into the urine.
Besides forming bones, calcium plays a critical role in helping muscles contract, nerve cells fire and blood to clot. Calcium is plentiful in seawater, but not on land – so when our ancient forebears crawled out of the ocean, they evolved ways to tightly regulate this essential mineral. "This is definitely a system where things need to be just right," says Shoback. If PTH levels are too high, people develop osteoporosis and kidney stones; too low, causes numbness, cramps and other serious problems.
Shoback, recruited to the San Francisco Veterans Affairs Medical Center (SFVAMC) in 1983, led studies in development of calcimimetics – drugs that trick the parathyroid glands into thinking that bloodstream calcium levels are high, thereby inhibiting PTH release. This research contributed to approval of the first calcimimetic to treat hyperparathyroidism – overly active parathyroid glands – and parathyroid cancer. She also made key discoveries about calcium-sensing receptors, which are found not only in the parathyroid glands, but also in almost every cell in the body. Shoback helped define how such receptors in cartilage interact with various hormones to regulate bone growth. "These cells are scoping out what's in the environment, because tissues have to have enough [calcium] to make a structurally competent bone," says Shoback.
She brings the same scientific rigor to caring for patients, many of whom have diabetes or osteoporosis. "Medicine is an art, but there is a lot of science involved," Shoback says. "It is a great advantage to be able to interpret new clinical research when making a recommendation to a patient." Says endocrinologist Anne Schafer, MD, "Dr. Shoback is constantly attentive to patients' needs, exceedingly thorough, and immensely compassionate."
One of Shoback's strongest role models was Johns Hopkins clinician Philip Tumulty, MD. "What was most impressive was how he dealt with situations where he couldn't come up with a diagnosis," she says. "He never abandoned his patients. He maintained a healing relationship. Many times with diabetes, the disease progresses. You may not be able to reverse deterioration of sight or kidney function, but the patient actually needs you even more at that point. You continue to be their doctor, and to support them and their family."
An esteemed educator and consultant, Shoback is internationally respected, and recently chaired annual meetings of the Endocrine Society and the American Society for Bone and Mineral Research. She is married to John Imboden, MD, chief of the Division of Rheumatology at San Francisco General Hospital and himself a Department of Medicine Master Clinician. They have two grown children, Tom and Elizabeth, and enjoy opera and international travel.