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When the girl was 14 months old, the mother consulted with a dietitian. The dietitian requested the patient's file from the doctor. After examining the doctor's notes and doing a thorough clinical history, the dietitian felt that the child might have an adverse reaction to cow's milk despite negative serum IgE. She decided to investigate the case further. When the doctor was queried about his suspicion of Munchausen syndrome by proxy, he stated that it was a mere possibility, but probably not the case. He said that the disease is very difficult to diagnose and that he did not want to spend much time on investigation. It did not seem as if the child were in any danger (i.e., her symptoms were not life-threatening and she was still gaining sufficient weight). Also, the symptoms were most probably caused by toddler's diarrhoea, a common problem in children of this age. It was established that the girl was exclusively breastfed until the age of 6 months, after which solids were gradually introduced into her diet. Wheat was included at 9 months without any adverse reactions. There were no reports of diarrhoea prior to her first birthday, when the mother introduced fish and cow's milk. She was not meticulous about possible traces of peanut and soya in the foods that she was giving her daughter. The mother was advised by her doctor not to introduce egg before the age of 2 years, as it could result in an allergy to egg. THOUGHT PROCESS: Through the clinical history, it was determined that fish was given only approximately once per week. It was thus unlikely that the child would react to it, because she presented with diarrhoea almost every day. Cow's milk was given quite often (at least once a day). It was given in the form of flavoured milk (which was convenient for the busy mother), yoghurt and as is, from the carton. Quantities fed varied between 80 and 150ml. Milk was also given in small amounts over breakfast cereal and in food such as white sauce. Milk would therefore be the most likely cause - although an adverse reaction to more than one allergen was also possible. The mother was, however, still convinced that cow's milk was the cause, since she had recognised a relationship between high intake (such as when the child drank a container of flavoured milk, approximately 120ml) and the onset of diarrhoea. The dietitian agreed that there was an apparently strong correlation between milk intake and the presence of symptoms, but could not say for certain that the child reacted only to large amounts.
The absence of specific IgE does not exclude an allergy (immunological reaction); it only excludes an IgE-mediated allergy. Cow's milk could thus still be the cause of the symptoms. The simplest way to diagnose a non-IgE-mediated allergy is by doing an elimination diet (symptoms should disappear) and then challenge the child with the suspected substance (symptoms should then reappear). The mother was asked to exclude all sources of cow's milk from her daughter's diet. Within two days the diarrhoea subsided. This was already a strong indication that cow's milk was the cause of the diarrhoea. To confirm the diagnosis, the mother was asked to challenge her child with milk. She started the challenge in the morning with a small amount and increased the dose throughout one day, to a maximum dose of 120 ml. However, no adverse reactions occurred within a couple of hours after the last dose was given. Late the next day, however, while the usual diet was being followed, diarrhoea reoccurred, even though milk was not ingested on that day. What could be possible
reasons for this?
Delayed reactions to milk of more than 24 hours have been recorded, especially with moderate and large amounts (as were given later on the day of the challenges). It should thus be queried whether the girl might have reacted to the milk approximately 24 hours after she ingested the 120ml dose (given in the evening of the challenges). This correlates with the mother's suspicion of a delayed reaction to moderate doses of cow's milk. Because Munchausen syndrome by proxy was queried before, it was decided to do a double-blind placebo-controlled challenge to make sure of this diagnosis. The mother was asked to, once again, exclude all sources of cow's milk from her child's diet. The symptoms disappeared once again. The girl was admitted to a clinic where challenges were done. Because the diarrhoea was thought to be caused by a moderate amount of milk (approximately 80-120ml), it was decided that a dose of 120ml was to be used to challenge the child. Rice milk was used as the placebo as the child had not had any adverse reaction to rice before. On the first day, she was given 120ml of rice milk. She had no adverse reaction for the following 3 days. She was then challenged with 120ml of cow's milk and developed diarrhoea approximately 24 hours later. It was confirmed that the child had a non-IgE-mediated reaction to cow's milk, which induced diarrhoea approximately 24 hours after a moderate amount of milk (120 ml) was ingested. Munchausen syndrome by proxy was thus not a relevant diagnosis. The mother received advice on excluding all sources of milk from her daughter's diet initially. As the girl did not have symptoms with small doses, it was then up to the mother to determine what level of intake her child could tolerate.
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