Objectives: Infants with milk protein intolerance are usually switched to a casein hydrolysate or amino acid–based formula, which they continue to receive until 1 year of age, when they are rechallenged with a cow's-milk or soy protein formula. To investigate whether some of these infants actually become tolerant sooner, this study gathered preliminary data for establishing an empirical timetable for the resolution of milk protein intolerance.
Methods: This prospective, longitudinal cohort study enrolled infants <4 months of age receiving either breast milk or a cow's-milk or casein hydrolysate formula who presented to a pediatric subspecialty practice during an 18-month period and had a positive stool guaiac test. After having been successfully switched to a casein hydrolysate or amino acid formula, infants who had guaiac-negative stools for at least 2 consecutive months were rechallenged with the formula that had necessitated the most recent switch.
Results: Of the 25 patients enrolled in the study, 16 completed the food challenge and data collection protocol. Negative stool guaiac tests following rechallenge indicated resolution of milk protein intolerance by the time subjects reached an average age of 6.7 ± 1.0 months (mean ± standard deviation). By the age of 7 months, milk protein intolerance was resolved in 12 of the 16 infants, the remainder having resolved by 10 months.
Conclusions: It may be reasonable to treat infants with milk protein intolerance for 2 to 3 months with a hypoallergenic formula, then rechallenge them at 6 months of age, usually without causing recurrence of the hematochezia. Rechallenging before 12 months old could result in cost savings to families and insurers.