Measuring your own blood pressure can help you and your doctor prevent or control hypertension and its many complications. Blood pressure readings in the doctor's office may be higher than at other times. The use of home blood pressure monitors can more accurately measure one's overall, or average,

We suggest that Medical Update readers who are over age 40 begin keeping a daily log of their blood pressure readings. Measuring your own pressure is neither expensive nor difficult. It's a good idea to take readings at different times of day, in case there is a difference between morning and evening values.

Many blood pressure monitors are approved for home use and available in drug, grocery and retail stores, as well as online. The simplest and least expensive device--an aneroid sphygmomanometer--consists of a blood pressure cuff connected by a rubber tube to a dial that registers pressure. A basic stethoscope is also needed. (See "The ABCs of Taking Your Blood Pressure.")

Other monitors feature automatic wrist and arm cuffs with digital displays and audio readouts. Some models print blood pressure measurement results with time and date, while others are capable of transmitting data over the telephone or Internet.

"Home blood pressure equipment of any type should be checked for accuracy at the doctor's office every six months," advises Dr. Myron Weinberger, director of the Hypertension Research Center at the Indiana University School of Medicine. "And batteries, if required, should be changed every month."

Dr. Weinberger told us that blood pressure monitors manufactured by Omron provide consistently accurate readings. Wrist and finger monitors are less reliable than those equipped with arm cuffs, he added. For more information on home blood pressure monitors, visit the Saturday Evening Post Web site, www.satevepost.org.