It's 3 a.m. on Sunday morning, and your doctor is out of town. Do you rush him to the emergency room? Take him to the local 24-hour urgent care center? Call your sister for advice? Consult the medical guide on your living room bookshelf? Chances are, you do none of these things. Instead, you pick up your bedside phone and call the emergency room of your local hospital.

The ordinary telephone is rapidly becoming an important source of health information. Roughly 30 percent of all contacts with health professionals now take place by phone. This figure is even higher in facilities that encourage telephone consultations. A number of health maintenance organizations (HMOs), including California's Kaiser Permanente Medical Plan, the country's largest, have now established formal telephone systems operated by phone advice nurses.

Then there are tape-based systems like Tel-Med, a national service which provides short prerecorded health tapes on more than 400 topics to hospitals, libraries, and other public service agencies. To hear a Tel-Med tape, you call a local number and request the tape you'd like to hear. Topics are listed in many local phone books. They range from asthma and athlete's foot to vaginitis and venereal diseases.

A call to my local Tel-Med service revealed that the Austin, Texas, facility is sponsored by the Austin Public Library. According to the Austin TelMed operator, tapes dealing with sexual subjects are far and away the most popular. "They're playing all the time," she said. "We've used them so much they're practically worn out."

She offered to play me her most popular tape. I could hear what she meant. The telephone is becoming an important source of health information. Roughly 30 percent of all contacts with health professionals now take place by phone.

"Masturbation is a very widespread and frequent experience in both sexes." The voice was that of a somber male radio announcer doing his best to impersonate a physician. The tape was scratchy and distorted, as if it had been played many times. "Masturbation itself cannot harm you. Concepts indicating that it will cause insanity, tuberculosis, sterility, impotence, pimples, blindness, and cancer have not been proven through scientific research." And so on.

Tel-Med is available in most cities. Consult your white pages for local listing. Or contact Tel-Med Inc., P. O. Box 1768, Colton, CA 92324, (714) 825-7000 for the name of the Tel-Med system nearest you.

Health by 800 Number. Nationwide phone health information centers—many of them available by toll-free numbers—are another important source of health information. Some current examples:

• American Medical Radio News Hotline. You can call 1-800-621-8094 anytime day or night for a prerecorded message reviewing the day's hottest medical news items. The messages include brief tape-recorded interviews with medical experts.
• Organ Donor Hotline. This service provides information on how to become an organ donor. Call 800-24-DONOR 24 hours a day.
• Gutline. A health counselor provides answers to your questions about digestive diseases. Call 301-652-9293 between 7:30 and 9:00 p.m. East Coast time, Tuesday evenings only.
• National Cancer Institute Hotline. Provides information on the prevention, diagnosis, and treatment of cancer. Can also provide publications and referrals to local organizations. Call 800-4 CANCER between- 9 a.m. and 4:30 p.m. your local time (your call will be directed to the nearest regional center) or (800) 638-6694 between 8 a.m. and 10 a.m. East Coast time.

For every institution that provides a toll-free number, these are a thousand facilities that don't use 800 numbers but do respond to calls. Every hospital, emergency department, doctor's office, clinic, home health agency, public health agency, and county medical society provides telephone advice. In the past, such calls have frequently been answered by nonprofessionals—telephone operators, office clerks, secretaries and receptionists. A growing number of centers now use standardized protocols to provide phone advice. Some hospitals lease proprietary phone advice systems such as Medinfo.

Telephones hold immense potential for improving the accessibility of health information. In the future, phone-based systems which provide emergency medical advice may be linked to existing 900 medical emergency numbers. Soon we'll be able to request health information from a computer by pushing the keys on our touch-tone phones.