Previous infant feeding guidelines recommended a delayed introduction of solids to beyond 6 months of age to prevent atopic diseases. However, scientific evidence supporting a delayed introduction of solids for prevention of atopic diseases is scarce and inconsistent. Current evidence does not support a major role for maternal dietary restrictions during pregnancy or lactation in the prevention of atopic disease. In studies of infants at high risk of developing atopic disease, there is evidence that exclusive breastfeeding for at least 4 months compared with feeding intact cow milk protein decreases the incidence of atopic dermatitis, cow milk allergy, and wheezing in early childhood. For infants at high risk of developing atopic disease who are not breastfed exclusively for 4 to 6 months, there is modest evidence that atopic dermatitis may be delayed or prevented by the use of extensively or partially hydrolyzed formulas, compared with cow milk formula, in early childhood. There is no convincing evidence that a delayed introduction of solid foods beyond 4 to 6 months of age prevents the development of atopic disease. For infants after 4 to 6 months of age, there are insufficient data to support a protective effect of any dietary intervention for the development of atopic disease.

Special formulas are those in which one of the basic nutrients (usually the protein and/or carrbohydrate) has been changed to an alternative nutrient that an individual baby may better tolerate. The following are specialized formulas : Soy formulas, hypoallergenic formulas, Lactose free formulas, Premature baby formulas, Low phosphate formulas, Formulas for inborn errors of metabolism. Less is known about the long-term effects of feeding babies these special formulas and each formula has its unique properties and indications. The pediatrician must acquaint themselves with all commercially available infant formulas so as to provide the parent with reliable and unbiased information about them.

Rectal bleeding is a common and worrisome problem in pediatric practice. The condition is usually alarming to patient and children. Although most cases are benign and self-limited, sometimes serious pathology also present in this manner. And severe rectal bleeding necessitates prompt diagnostic notice and appropriate treatment. The etiologies of rectal bleeding are somewhat specific to certain age group in children. Accurate history and through physical examination are paramount importance to help differentiate of the diverse etiologies causing rectal bleeding in children. This review describes patterns of rectal bleeding, historical and physical aspect, differentiation of clinical characteristics of rectal bleeding according to etiology, and diagnostic investigations.

The causes of liver disease in children and abnormal liver function test are more diverse than those in adult. Therefore, the first step to evaluate the liver disease is the understanding the liver disease and interpreting the appropriate liver function test in children. The characteristics of each test and various conditions which we encounter in outpatients settings will be discussed in this article, especially focused on elevation of aminotransferase level without identifiable causes.

The knowledge of motility disorders of the gastrointestinal tract has increased over the past decades. The development of newer therapies for bowel motility disorders has been disappointingly slow. Prokinetic agents are medications that enhance coordinated gastrointestinal motility and transit of material in the gastrointestinal tract. These agents are pharmacologically and chemically diverse. However, life-threatening adverse effects of prokinetic agents such as cisapride was present. In this review, pharmacologic effects and use of prokinetic agents in children was introduced.

Enterobiasis and head lice infestations, contact-borne parasitic diseases, are the most prevalent parasitic infections of children in Korea, and they are transmitted by close contact with infected persons. They are not of major concern in public health, therefore their importance in children's health care are overlooked in Korea. Egg positive rates of Enterobius vermicularis have been reported to be 10~20% among children in kindergartens and primary schools. Enterobiasis is diagnosed by scotch tape anal swab, but repeated examination is necessary for accurate diagnosis. Albendazole or mebendazole are extremely effective for treatment, however, reinfections usually occur if treatment is not repeated at least three times at a 3-week-interval, targeting the whole family members including the patients. Environmental sanitation and health education are also necessary to guarantee the successful treatment of enterobiasis. Head lice infestation is still an indication of public health status. Children of 3 to 12 years old and their families have infestations more frequently, and girls have more than boys. Diagnosis can be made by identification of live lice or nits on the head. Pediculicides are effective treatment of infestations, however they do not kill nits completely, requiring second treatment. Recently wet combing is preferred as an alternative by parents in England because of possible toxicity of drugs and resistance of lice. It is impossible to completely prevent enterobiasis and/or head lice infestations. Therefore, mass screening and prevention are required, and, in local clinics, a thorough evaluation of the symptoms and past history, and appropriate laboratory tests are necessary.

Chronic functional constipation is a common problem in childhood, with soiling a significant issue. It presents a management problem for pediatrician, and parental concern is high. About 5% of pediatric patients is known to have constipation and/or encopresis which is the second most referred disease in pediatric gastroenterology clinic, accounting for up to 25% of all visits. The etiology of constipation was based on initiation factors including vicious cycle concept, genetic factors, psychological factors, dietary influences and histologic abnormalities of colon. Emphasis is placed on the evaluation and management options that are available to the treating pediatrician. Careful history taking is most important to diagnose functional constipation. In addition, diagnostic tests such as plain abdominal radiograph, colonic transit study, anorectal manometry, barium enema were helpful to diagnose the constipation. Childhood constipation can be very delicate to treat. It often requires prolonged supports by physicians and parents, demystification, medical treatment and especially with the child and parent's cooperation.

Gastroesophageal reflux (GER) defined as passage of gastric contents into the esophagus without symptoms is a common physiologic gastrointestinal problem in infants, children and even in adults. But gastroesophageal reflux disease (GERD) defined as symptoms or complications of GER is a disease entity to find out the reason and treat. After the era of 1970 we have been studying about GERD with the development of diagnostic and therapeutic methods. I already introduced the nature and the fundamental knowledge of GERD in the opening symposium of KSPGHAN in 1998. Now, I will introduce the guidelines for evaluation and treatment of GERD which was recommended by the North American Society for Pediatric Gastroenterology and Nutrition and American Pediatric Association which was published in 2001. And I will introduce progressing subjects and the forecoming issues to be solved in near future. Those are as followings. Does GERD cause otolaryngologic symptoms such as chronic sinusitis and chronic otitis? Is GERD inherited? Can we find out the child who will become GERD in adult life and the way to reduce the incidence of Barrett's esophagus and esophageal cancer? Is long term PPI therapy safe in children?

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism that results in accumulation of copper primarily in the liver, the brain and the cornea. Mutations in the WD gene, ATP7B cause failure of copper excretion from hepatocyte into bile and a defective synthesis of ceruloplasmin. More than 370 mutations are now recognized, scattering throughout the ATP7B gene. Since WD has protean clinical presentations, awareness of WD in clinical practice is important for the early diagnosis and prevention of accumulated copper toxicity. None of the laboratory parameters alone allows a definite diagnosis of WD. There are numerous pitfalls in the diagnosis of WD. Low serum ceruloplasmin concentrations, increased 24 hour urinary copper excretion, increased hepatic copper concentrations and the presence of Kayser-Fleischer rings in the cornea are major diagnostic points. A combination of any two of these 4 laboratory findings is strong support for a diagnosis of WD. Molecular methods are now being used to aid diagnosis. Molecular genetic testing has confirmed the diagnosis in individuals in whom the diagnosis is not clearly established biochemically and clinically. Siblings should be screened for WD once an index case has been diagnosed. Discrimination of heterozygotes from asymptomatic patients is essential to avoid inappropriate lifelong therapy for heterozygotes. Genetic testing, either by haplotype analysis or by mutation analysis, is the only reliable tool for differentiating heterozygote carriers from affected asymptomatic patients. Currently, genetic testing is of limited value in the primary diagnosis. However, genetic testing will soon play an essential role in diagnosing WD as rapid advancement of biomedical technology will allow more rapid, easier and less expensive mutation detection.

Helicobacter pylori is the causative agent of chronic gastritis and has a role in the pathogenesis of peptic ulcer diseases, and gastric cancer. There have been reports suggesting a close link between these gastroduodenal disorders and a state of vitamin C deficiency. In this paper, the past, present and future perspectives on H. pylori infection and vitamin C will be discussed under the following view points. Since the ecological niche of H. pylori is the mucus layer and intercellular junctions of the gastric epithelium, the various kinds of host inflammatory cells motivated by the local and systemic immune responses cannot eliminate the microorganisms. When the invading foreign body is not removed, despite full activation of defense mechanisms, adverse consequences of the immune responses develop on the host gastric mucosa. The reasons for the body vitamin C depletion could be explained as follows; 1) the increased vitamin C consumption by increased oxygen free radical production through the prolonged hypersensitivity reactions in the gastric mucosa, 2) the increased vitamin C oxidation by the nitrite which is formed from nitrate reduction by the intragastric bacteria proliferated in the hypochlorhydric gastric cavity, 3) the strong ${\gamma}$-glutamyltranspeptidase activity of H. pylori which depletes the glutathiones in gastric mucosa. Depletion of glutathiones in the stomach favors irreversible oxidative destruction of ascorbic acid. Both persistent inflammatory burdens in the stomach by H. pylori and resultant vitamin C depletions synergistically and uninhibitedly might aggravate the hypothetical sequence of gastric carcinogenesis: atrophic gastritis${\rightarrow}$intestinal metaplasia${\rightarrow}$dysplasia${\rightarrow}$gastric adenocarcinoma. High intake of vitamin C could reverse the hypothetical sequence of the gastric carcinogenesis via direct and indirect effects on H. pylori and host-parasite relationships.

보호자와 의사관계에서 가장 중요한 것은 신뢰이며, 특히 소아청소년과 좋은 관계를 유지하며 원칙적이면서도 구체적인 방법을 같이 의논하여 결정한다. 보호자가 이미 알고 있는 단편적인 의학지식을 잘 엮어서 통합하여 주고, 신체활동과 함께 상담하여야 한다. 1. 에너지 소비와 섭취의 균형을 유지해야하는 원칙을 강조한다. 맛있는 음식이 있을 때 과식하는 것은 사실 당연하다. 많이 먹었을 때 많이 움직여야 한다는 것을 강조한다. TV시청시간과 컴퓨터사용시간을 2시간 이하로 제한하고, 신체활동은 1시간 이상 될 때까지 증가한다. 2. 치료의 목적은 건강한 식습관으로 개선하여 평생 건강하게 지내는 것이 목적이다. 단순히 절식하는 것이 아니며 평생 건강할 수 있도록 좋은 습관으로 개선하는 것이다. 3. 건강하게 음식을 선택하는 방법을 교육한다. 소아청소년 비만은 성인비만으로 연결되며, 결국에는 대사증후군으로 당뇨나 고혈압 등 합병증이 오게 되므로, 음식을 어떻게 선택하는 것이 건강한지 설명한다. 4. 야채와 과일 섭취를 권장한다. 5. 음료수도 음식과 같이 생각하여 달콤한 음료수를 먹지 않는다. 6. 칼슘섭취를 위하여 저지방이나 무지방우유를 권한다. 7. 가족과 함께 식습관을 개선하다. 아침 먹기, 밤늦게 먹지 않기, 모든 음식 천천히 먹기, 씹지 않고 물과 함께 삼키지 않는지 확인하고 개선한다. 가족과 함께 식사하는 횟수를 늘린다. 부모는 자녀의 모범이 되어야 한다.

최근 소아, 청소년의 비만이 늘고 있는 추세이다. 소아 청소년의 비만치료는 섭취열량과 소비열량과의 균형을 맞추는 것이 가장 중요한 원칙이다. 소아, 청소년기는 성장과 발달이 왕성한 시기이므로 단식, 절식 등의 식이요법만으로 단시간 내에 체중을 감량하는 것은 바람직하지 않다. '몸짱'같은 건강한 몸매는 운동을 통하지 않고는 이룰 수 없다는 인식을 심어주며 성장에 지장을 주지 않는 범위 내에서 적당한 운동을 유도하는 것이 좋다. 소아는 의지가 약하고 인내심이 부족하므로 부모와 가족의 이해와 협력이 필요하며, 아동이 좋은 습관을 가질 수 있도록 아동의 수준에 맞는 적당한 운동 프로그램을 제시하는 것이 요망된다. 아동에게 억지로 운동을 강요해서는 안되며, 본인이 재미있어 하면서 충격이 심하지 않은 운동을 선택하도록 한다. 하루에 1시간 정도의 운동이 필요하지만 전혀 움직이지 않던 아동은 수시로 짬짬이 움직일 수 있는 상황을 제공해주는 것이 중요하다. 비만은 체중을 단기간에 감소시키는 것이 아니라 '평생에 걸쳐 조절하여야 하는 것'으로 인식되어야 할 것이다.

Immunonutrition is the provision of specific nutrients that modulate the activity of the immune system. Several nutrients including arginine, glutamine, nucleotides, omega-3 fatty acids, vitamins, minerals, and prebiotics can be provided to enhance immunity in critically ill patients. Supplying immunonutrition to critically-ill children, better prognosis and shortening of the hospital stay are expected from its immuno-modulating effects. Therefore, immune-enhancing enteral and parenteral formulas can be recommended in children with severe illness.

Trace elements compose a very small portion of the body, however they have a variety of essential functions. Various diseases are caused by trace element deficiencies, and sometimes they can be fatal. Long-term TPN is a risk factor of trace element deficiency, and trace elements need to be checked regularly while receiving TPN. It is important to provide sufficient requirements of trace elements regarding the clinical features and the problems of trace element excess or deficiency. Moreover extensive studies to establish the efficiency of examining human hair and nails, recent method to determine the trace elements, are required.

According to the hygiene hypothesis, westernized and urbanized life style leads to the increase of allergic disease. This hypothesis supports the use of probiotic therapy for the prevention or treatment of food allergy. The probiotics which contains potentially beneficial microorganism have been used for the treatment of some gastrointestinal disorders and atopic disease as dietary supplements. Many results of studies support the immunologic bases of probiotics therapy. The most important mechanism is that probiotics suppress Th2-skewed immunity as the stimulation of regulatory T cell. The difficulties of diagnosis of food allergy, variable symptoms, many kinds of microorganism, diet style and non-standardized study designs are attributed to the variety and controversy of the effectiveness of probiotics in food allergy with infant and children. More studies is needed to confirm the efficacy of probiotics in infant and children with food allergy.

In patients with functional gastrointestinal disorders, dietary factors have an important effect on the development or worsening of gastrointestinal symptoms. Therefore, nutritional advice is often needed for the treatment of these patients. Although no firm conclusions can be drawn from current studies, the use of low-fat diets can be recommended in patients with functional dyspepsia. Constipation can be treated with a high-fiber diet. There are few studies in irritable bowel syndrome patients with diarrhea. The diet recommendations must be applied to each patient depending on symptoms.

조사에 의하면 정상적으로 발달하는 유아 아동의 25%~40%정도가 발달의 어떤 단계에서 섭식에 문제를 보일 수 있다고 한다. 많은 경우에 특별한 전문가적 도움없이 발달 과정을 거치면서 문제가 저절로 해결되는 경우도 있으나, 그 중 일부는 성장과 발달 및 가족 생활에 큰 스트레스가 될 정도의 섭식문제를 보이며 심한 경우 그 문제가 오랫동안 지속될 수 있다. 섭식문제는 섭식 그 자체의 문제뿐 아니라 음식거부를 위한 다양한 문제행동을 수반하게 되는데, 기존의 연구 결과는 행동수정의 한 형태인 응용행동분석이 가장 효과적인 치료법이라 보고한다. 문제가 극심한 경우엔 다학제적 팀으로 구성된 전문적인 치료가 필수적이나, 중경도의 문제는 그 종류에 따라서 부모교육을 통해 해결될 수 있기도 하다. 섭식 치료에는 문제를 규명하는 평가 절차가 가장 먼저 선행되어야 하며, 이를 근간으로한 치료책을 개발하고 적용할 때 가장 효과적인 결과를 얻을 수 있다. 치료는 보이는 문제 유형에 따라 달라져야 하는데, 유아 아동들이 가장 빈번하게 보이는 섭식문제 종류와 그에 적절한 구체적인 방법들을 제시하였다. 마지막으로, 부모교육을 통해 유아 아동의 섭식문제를 다룰 때 전문가들이 고려해 주어야 하는 사항들에 대해서 열거해 보았다.

비만으로 인해 체지방이 증가하면 증가된 지방에서 분비되는 여러 가지 사이토카인과 지방산에 의해 인슐린 저항성을 유발시키며, 인슐린 저항성으로 인해 이상지혈증, 고혈압, 심혈관계 질환, 제 2형 당뇨, 비알코올성 지방간염, 다낭성 난소 증후군 등이 발생한다.