Taking body temperature

YOUR HEALTH

DR. DONOHUE

DEAR DR. DONOHUE: My friend has an 11-month-old daughter who had an E. coli blood infection. The child shuddered once, was a bit lethargic, but felt cool to the touch. The digital ear thermometer registered normal. My friend's instinct was to go to the hospital. The baby had a temp of 105. Are digital thermometers ineffective? -- G.W.

ANSWER: "Digital" refers to the way information is displayed -- in digits (numbers). A digital watch shows time as 10:02, for example, not with a large hand pointing to the minute and the small hand to the hour. The issue with thermometers is not how they display body temperature -- digitally or not -- but which body site gives the most accurate reading.

Rectal temperatures are subject to fewer vagaries than temperatures taken at other body sites, and the Canadian Pediatric Society recommends rectal-temperature-taking for children up to 5 years of age. It doesn't matter if the temperature is displayed digitally or on a gauge with degrees.

Ear thermometers are accurate to within 0.2 F (0.1 C). They use infrared sensors to measure the heat given off by the eardrum and surrounding tissues. Placement can be a problem, especially with young children.

Plastic strips with liquid crystals are applied to the forehead to give a rough idea of body temperature. Their readings are affected by sweat, the surrounding air temperature and the finger temperature of the one applying and removing the strip. They should be used only for rough estimates.

For older children and adults, oral temperatures are reliable. Hospitals routinely take them, and the reading can be displayed digitally.

Your friend is blessed with common sense. Severity of illness should not be based on one finding -- temperature, for example. A blood infection with E. coli can cause a drop in body temperature, and looking for a high temperature could be misleading. The baby's temperature might have risen en route to the hospital.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475.