Fernando Viteri

Development of an Interval Sampling Hydrogen (H2) Breath Test for Carbohydrate Malabsorption in Children: Evidence for a Circadian Pattern of Breath H2 Concentration

Summary: We have applied the gas chromatographic analysis of hydrogen (H2) in expired air to the determination of carbohydrate malabsorption in children. A compact, inexpensive, and simple gas chromatograph was specifically adapted to the measurement of low concentration of H2. A collection procedure using the sampling of expired air at evenly spaced intervals with a low resistance facemask was used to obviate the need for closed, continuous rebreathing systems of breath collection.Under different experimental conditions, H2 concentrations ranged from 11–166 ppm. During fasting, however, H2 concentrations in preschool children were extraordinarily stable and uniform. The velocity of H2 excretion from graded doses of 1.5, 3, and 6 g of the nonabsorbable disaccharide, lactulose, was linear with a response of 1.2 cc H2/2 hr/g nonabsorbed carbohydrate. Formal clinical lactose tolerance tests were devised using the oral administration of 1.75 g lactose/kg body weight. The increase in II2 concentration was compared with the rise in plasma glucose. Maximum increases in H2 concentration of less than 15 ppm corresponded to a rise in plasma glucose greater than 20 mg/dl; increases in H2 of more than 20 ppm were uniformly accompanied by flat glucose curves. Increases in H2 concentration between 15 and 20 ppm comprised a borderline zone in which both flat and normal glucose curves were seen. The normal absorption of the monosaccharide constituents of lactose, glucose, and galactose, as demonstrated by increments of less than 15 ppm in H2, indicates that the lactose intolerance was due to failure of digestion of the disaccharide rather than to decreased mucosal absorption of the monosaccharide products.When H2 concentration was measured at 120-min intervals over periods of 24 hr in children on a normal diet, a 2.5-fold or greater increment in breath H2 concentration was observed at some time during nocturnal sleep. Moreover, the increase in H2 concentration to a standard dose of 6 g lactulose was greater during induced sleep than in the awake subject.Various pitfalls to the interpretation of clinical carbohydrate absorption tests using breath H2 were identified. These included an occasionally elevated baseline concentration of H2, delayed gastric emptying, and previous administration of broad spectrum oral antibiotics. The test is noninvasive, well tolerated, semiquantitative, and ideally suited for use in children.Speculation: The noninvasive, interval sampling of H2 breath test will provide a more versatile, widely applicable, and better tolerated index of carbohydrate malabsorption in the pediatric population than conventional methods using blood glucose determinations, and will prove to be the preferred method for testing carbohydrate tolerance in children.

Clinical Aspects of Protein Malnutrition

Publisher Summary This chapter discusses the clinical aspects of protein malnutrition. Protein malnutrition tends to be manifest primarily in young children and is a major factor in the high mortality rate of children in the 1–4 year age group, which in technically underdeveloped areas is 20 to 60 times greater than in the United States and Western Europe. Most of the excessive mortality of preschool children characterizing these areas is because of the interaction between protein malnutrition and infection. Very young children are less likely to suffer from protein deficiency because of the probability that they can be receiving breast milk when the parents cannot afford other food sources or cannot use them properly. The multiple factors responsible for protein malnutrition can be conveniently classified as those relating to the agent, the host, and the environment. A large majority of the preschool children in the areas where the acute protein malnutrition of kwashiorkor is prevalent go through a period of chronic protein deficiency.

H2 BREATH TESTS DURING DIARRHEA

Abstract. The peak rise in breath hydrogen and the volume of excess pulmonary excretion of hydrogen in response to a 10 g dose of the non‐absorbable disaccharide, lactulose, was significantly lower in children with active gastroenteritis and diarrhea than in non‐diarrheal controls. Thus, despite the fact that the H2 breath test is a convenient, noninvasive technology for use in children, it cannot be recommended for measuring carbohydrate malabsorption in individuals with active, on‐going episodes of diarrhea.

PRINCIPLES OF TREATMENT AND PREVENTION OF SEVERE PROTEIN MALNUTRITION IN CHILDREN (KWASHIORKOR)

I t is now generally recognized that kwashiorkor is the result of a severe deficiency of dietary protein a t an age when the essential amino acids are required in relatively large quantities for growth. In most children developing kwashiorkor the protein intake is deficient, not only in quantity, but also in quality. Thus, the diets that are responsible for the syndrome usually contain protein that, due to its low biological value, is poorly utilized. If protein deficiency occurs in children who are receiving an adequate or even excessive quantity of calories, as has been reported in Jamaica, the resulting clinical picture is that of classic kwashiorkor. This form is characterized by edema, lesions of the skin, hair changes, apathy, anorexia, enlarged fatty liver, and low serum protein. These children also have abundant subcutaneous fat and recover rapidly with a high protein diet; when they loose their edema there is no wasting evident. In the majority of the regions of the world in which kwashiorkor is found, however, children after weaning receive diets that are deficient not only in protein but also in calories. The clinical picture differs from that of classic kwashiorkor in that the children often show a considerable degree of tissue wasting, and the response to treatment is much slower. They are characterized by a reduction in statural growth and in weight, marked diminution or even absence of subcutaneous fat, and a much greater degree of muscular wasting; the liver, although it shows fatty change, is usually not increased in size. Since these children have a marasmic appearance when their edema is lost, this form of malnutrition is spoken of as marasmic kwashiorkor. The diets of children developing kwashiorkor are not only low in protein, but are also deficient in other essential nutrients, particularly in the marasmic form of the disease. For this reason and also because their absorption is reduced:, a deficiency of fat-soluble vitamins is a particularly common accompaniment of kwa~hiorkor.~ Signs suggestive of B -complex vitamin and iron deficiencies are also frequently found Due largely to

Hematological changes in protein calorie malnutrition.

Publisher Summary This chapter discusses the clinical description of the anemia of protein calorie malnutrition (PCM). PCM of various degrees is the most prevalent disease of nutritional deficiency in the world. It affects primarily the young child, although older children and adults of both sexes are not spared. PCM remains one of the major killers in children even when treated in the hospital. Pallor and anemia are among the chief signs of PCM. The present understanding of the anemia of protein calorie malnutrition in children stems from clinical observation, human experimental work, and animal research. The hematological changes observed in children with severe protein calorie malnutrition are primarily an adaptation phenomenon to decrease lean body mass to which various deficiencies and disease states could add their own characteristic changes. The hematological alterations in protein calorie malnutrition must be viewed as a dynamic phenomenon of balance between body composition and the erythron.

Studies regarding the impact of micronutrient status on behavior in man: iron deficiency as a model.

In studies conducted in both Cambridge, Massachusetts and Guatemala (1), we have obtained data confirming our hypothesis that iron nutrition affects cognitive function in children (2, 3). The design and conduct of these studies led us to realize the great complexities involved both in the definition of nutritional status in man and in the selection of relevant measures of cognitive function. Herein, we present some of our approaches to these problems. The first section deals with problems surrounding the measurement of iron status; the second deals with issues relevant to the quantitation of cognitive function in children and to the cross-cultural comparability of such data.

INCAP Studies of Kwashiorkor and Marasmus

This article summarizes thirty years of intensive clinical metabolic and therapeutic studies of the consequences of severe protein deficiency relative to calories, which results in kwashiorkor, and of a balanced deficiency of protein and calories that results in marasmus. Evidence is provided that these are two different metabolic diseases, but kwashiorkor is usually superimposed on some degree of chronic marasmus and hence most cases studied were marasmic kwashiorkor. The value of the creatinine/height index to indicate the degree of lean body cell mass with any disease is demonstrated.

Application of receiver-operator analysis to diagnostic tests of iron deficiency in man.

Summary: The objective of the present report is to demonstrate the use of receiver-operator characteristics (ROC) analysis in the selection of diagnostic tests for iron deficiency in a specific population. Conventional ROC curves were prepared with true positive fraction (TPF) and false positive fraction (FPF) determined by the application of different cut-off points for four indicators of iron status. ROC plots were then transformed into normal deviate scales. The advantages of Gaussian transformation of TPF and FPF when underlying decision functions are normally distributed are: (i) the ROC curve is a straight line; and (ii) the separation between the two distributions and shape of these distributions can be simply quantitated as intercepts and slopes. In the present study, pretreatment hemoglobin concentration was the most robust diagnostic indicator of iron deficiency as operationally defined by a response of hemoglobin to iron treatment. Free erythrocyte protoporphyrin was a more sensitive and specific predictor than either serum ferritin or transferin saturation when a stringent operational definition of iron deficiency was used. These findings illustrate the utility of ROC analysis in discriminating between diagnostic indicators having different degrees of accuracy.