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In "Taking a rational approach to the choice of formula" (August 2001), Dr. Georgieff makes the point that true cow-milk allergy can only be diagnosed with a double-blind, placebo-controlled challenge test. How is such a test to be performed? I know of no way to hide the distinctive odor and taste of Nutramigen formula. It is extremely unlikely that a mother would not know which of the two test formulas her infant was receiving at any given time.
The author replies: Thanks to Dr. Brody for pointing out a tricky issue for the general practitioner. I agree: There is no way to hide the distinctive odor of the casein hydrolysate formulas, so a direct switch between one of those formulas and a conventional cow-milk formula would be obvious to the parent. One approach is to put the child on the casein hydrolysate formula, and then reintroduce a small amount of conventional cow-milk formula into the bottle. Doing so would likely not change the odor, and only a small dose of the potentially offending protein would be introduced in the diet.
Having said that, it is extremely important to assess the degree of suspicion of cow-milk allergy before embarking on the challenge. If suspicion is high and the risk of anaphylaxis is present (the child, for example, has had hives, wheezing, or other allergic symptoms on cow-milk formula), the trial should be performed only by a pediatric allergist, if at all. If suspicion is low (that is, the symptoms are nonspecific), the trial may not be warranted or the infant could be put on a soy protein formula and followed. When performing these trials or switching formulas because of allergies, pediatricians should remember that the Food and Drug Administration has designated only casein hydrolysate formulas as hypoallergenic.
On a separate point, my article stated that the caloric density of standard formulas is 67.6 kcal/L. It is, in fact, 67.6 kcal/dL.
It is time for us to practice what we preach: "Don't put anything in your mouth unless it's food or medicine." How does Dr. Newman ("Plastic tubing beats bulbs for pneumatic otoscopy," Clinical Tip, August 2001) stay healthy putting tubing in his mouth 20 to 30 times a day? And what does he do when examining a child in an ER where there isn't any tubing but just a bulb and connector? Or when he's teaching students or residents?
I've learned to use the bulb with great ease and efficiency using the ambidextrous technique. When I look in the left ear, I hold the otoscope in my left hand (with the back of my hand against the cheek), pull on the pinna with the thumb and index finger of my right hand, and gently squeeze the bulb with my third, fourth, and fifth fingers against my palm. (For the other ear, I do the opposite.) With a little practice it becomes second nature. It's time we all learn to use the bulb.
The author replies: I appreciate Dr. Rzepka's interest. "Don't put anything in your mouth unless it's food or medicine" isn't something I've ever preachedwhat about wind instruments and toothbrushes? I think the point is not to share; I give every trainee his or her own tubing. I have my own otoscope and the tube fits easily in the case. I do put a small piece of tape on the tubing that I give away, to indicate the otoscope end; that way the end that has been in a trainee's mouth does not go into a shared otoscope.
Once you have learned to use the bulb, it is fine if it is available. Where I work, bulbs kept disappearing, especially before I started handing out plastic tubing. I also think bulbs are harder for beginners to learn to use. Most of the trainees I teach have never seen an eardrum move and find bulbs awkward to use, even with their dominant hand.
Readers' Forum. Contemporary Pediatrics 2001;12:92.