You recently said that lower-than-normal systolic blood pressure is safe as long as it causes no symptoms. Can a low diastolic pressure be harmful? —C.W., by e-mail

Probably not if your systolic level is normal. But if that level is high, the wide pulse pressure—or the difference between the diastolic and systolic levels— can indicate heart-valve problems, a weakened heart muscle, severe anemia, an overactive thyroid, and other problems. And some research suggests that a low diastolic, by itself, might be dangerous in people with coronary disease. A study of more than 20,000 such people found that a diastolic of 60 millimeters of mercury (mm Hg) or less tripled the risk of death compared with pressures between 71 and 90 mm Hg, independent of the pulse pressure. Diastolics between 60 to 70 mm Hg doubled the risk. If your diastolic is 70 or less, ask your doctor if you should be concerned, especially if you also have a high systolic level or are being treated for coronary disease.