A report issued Tuesday by the CDC finds that nearly a third of U.S. adults (nearly 67 million people) have hypertension — and that more than half of those people do not have their condition under control. Those estimates are based on data for nearly 23,000 participants in the federal National Health and Nutrition Examination Survey (NHANES) from 2003 to 2010.

Hypertension, or high blood pressure, is a major cause of cardiovascular disease and death and accounts for $131 billion in health-care costs each year, the report notes. In this assessment, a person was deemed to have high blood pressure if his average systolic reading was 140 millimeters of mercury (mmHg) or higher or his diastolic reading was 90 mmHg or higher, the authors say.

The first step in controlling high blood pressure is recognizing that you have it; hypertension is notoriously a “silent” disease that does damage to your cardiovascular system without causing noticeable symptoms. Once detected, the condition can be controlled by medication and, in some instances, by making lifestyle changes such as reducing sodium consumption and increasing physical activity. (Among the limitations noted in this report, the only treatment included in the data was use of blood-pressure medication; the roles of lifestyle and diet changes were not addressed.)

About 14.1 million of those with uncontrolled hypertension weren’t aware they had high blood pressure in the first place. An additional 5.7 million knew they had it but weren’t taking medication to treat it, while 16 million of those whose hypertension remained out of control were aware of their condition and actually taking medication to treat it.

The situation is apparently not mostly due to lack of access to health care or insurance coverage: Among the 35.8 million people with uncontrolled hypertension, fully 89.4 percent had a “usual” source of health care and 85.2 percent had health insurance. Rather, the report observes, opportunities for health-care providers to screen, intervene and help steer people toward controlling their blood pressure are probably being missed.