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Pediatric Gastroenterology

Certain conditions appear at different periods during a child’s life. For example, during the neonatal period these are perhaps the commonest causes of chronic diarrhea and malabsorption. Now some of them may not appear clinically until even after the first month of life, but others are so recognizable in the first day of life that the infant is unlikely to leave the hospital. A good example of this would be an infant born with congenital glucose-galactose malabsorption. Because in the nursery, if the baby is given glucose water he is going to start out with watery diarrhea. 

If that isn’t done, the baby is basically put at the breast and has diarrhea from the beginning, it could be due to congenital lactase deficiency. On the other hand, it could be due to the fact that when that lactose is broken down into glucose and galactose the baby will have diarrhea. So again, these two conditions are going to be clinically apparent.

Cystic fibrosis, as you know, can present not only with meconium ileus or with meconium peritonitis, but it can present with a watery diarrheal syndrome. Sometimes it’s not as apparent to the clinician in that first day of life, but it certainly may be later on during that early period of infancy. Shwachman-Diamond syndrome also likewise can present with malabsorptive diarrhea during the first days and weeks of life, but the baby may leave the hospital.

Congenital short-bowel syndrome. The babies with this may make it out of the hospital depending on the amount of intestine they have available. Usually the patients, unless they have more than half of their small intestine, will not have normal absorption. So these youngsters usually have 50% of the normal intestinal length. Microvillus inclusion disease, an inherited disorder that we’ll talk about a little bit later. But this condition will usually present in the first few days of life.

Celiac sprue we’ll talk a little bit more about later. This is probably the commonest chronic cause of generalized malabsorption that we see in this age group, and it also can be seen in the older child. Shwachman-Diamond syndrome in cystic fibrosis may also become recognized at this time. And again, the allergies. The list goes on. Intestinal hemangiectasia, congenital sucrase-isomaltase deficiency, this condition depends on when juice and fruits are added to the diet. Unless one adds juice or fruits you are not going to see manifestations of it. Again, it typically presents when these foods and juices.

Watery diarrheas. For the most part the ones that we see in practice are osmotic diarrhea. Pure carbohydrate malabsorption. There are four juices that can cause it, as indicated here. But in practice it is primarily apple juice and pear nectar that do it. The transport of monosaccharides is dependent primarily on a sodium-dependent ATPA system.

Lactase deficiency: there are two. There is primary congenital and the so-called late onset. The primary congenital is extremely rare. I mean, there have been less than a handful of cases that have ever been documented. But the late onset is the most common cause of the genetically determined cause of carbohydrate malabsorption. It occurs from the point of weaning all the way to adulthood. Again, certain ethnic groups develop earlier than others. In people who are from China, Korea, Japan you see lactase deficiency beginning as early as age two. In people who are Hispanic background, it’s usually around about age four.

Congenital glucose galactose malabsorption, very rare. We already said it presents at birth. These infants usually do not get out of the hospital. Fructose is the only carbohydrate these infants can tolerate. Congenital sucrase-isomaltase deficiency, autosomal recessive. The true incidence is unknown. It’s interesting, the only ethnic group that we know that has this in great amounts is the Eskimo. So if you go up to Alaska you have to know that the Eskimos are lactase deficient and 10% of them are sucrase-isomaltase deficient. And they have a lot of problems with diarrhea. Again, diarrhea and abdominal pain or bloating when in contact with sucrose, corn starch and corn starch can also cause these symptoms. Also, interestingly enough, rice cereal. Because it contains isomaltose. Symptoms are variable in onset. It depends on the time of introduction of juices, fruits.

Mixed malabsorption: what we are talking now about patients who have a problem with absorption of carbohydrate, fat and protein. Of the chronic diseases celiac sprue is probably the best example of a condition that does this. Another one is post-viral gastroenteritis. One sees this is patients who have a Rotavirus infection as well. These symptoms in celiac sprue can be diarrhea, abdominal distention occurs because of the maldigestion and malabsorption. The maldigested and malabsorbed nutrients stay in the lumen of the gut. They pull water into the lumen of the gut, which gives you the distention of the bowel loops.

Autoimmune enteropathy characterized by intractable diarrhea can present in the first month of life. Severe proximal small bowel damage. They have autoantibodies to gut epithelium. It is an anti-enterocyte antibody is what is going to be positive.

Microvillus atrophy disease; this is again usually in families where there has been intermarriage. In this country and in Canada most of the patients who have been seen are patients who have come from the Middle East where it is not uncommon to marry a first cousin. And virtually all the cases that have been recognized have been due to first and second cousins marrying. They have intractable diarrhea from birth, generalized malabsorption.

Lumenal maldigestion and malabsorption. Cystic fibrosis is obviously the commonest cause of lumenal maldigestion that we see. You need to be aware that not all patients with cystic fibrosis have maldigestion and malabsorption. Eighty percent do, 20% of the cystics will have normal digestion of fat and protein.

Shwachman-Diamond syndrome. Now what you find in Shwachman-Diamond syndrome is the volume of their secretion is normal. That separates them from cystic fibrosis. Their bicarbonate fluoride exchange mechanism is intact. That’s different from CF patients. They have a deficiency of pancreatic enzyme production that is primary. So they differ from CF in this. That they really have a primary defect in enzyme production. They have normal sweat chloride secretion. These patients may also have a variety of other associated anomalies that are found. For example, they can have pan- hypogammaglobulinemia. These patients also, in terms of their bone marrow, can have a normochromic or normocytic anemia.

Protein-losing enteropathy; just remember that cows milk and soy protein enteropathy in the older infant, above six-months-of-age, often presents with a hypoproteinemia as well as peripheral eosinophilia with increased eosinophils in their stool. They may not have a history of steatorrhea. Their presentation may just be the infants.

Allergic cows milk allergy, soy milk allergy. Again, have to bring that up. As a matter of fact probably the commonest cause of blood-tinged diarrhea or blood-streaked diarrhea in the first three months of life, is allergy to cows milk and soy milk allergy. Also you may see mothers who breast feed their infants, who are drinking a lot of milk. They may, through their milk, transmit the antigen from the cows milk or from the soy to the baby and the baby can get it in that fashion. One of the other things to recognize about babies who have allergic reactions to cows milk and soy milk, they usually come from families that are very atopic. It’s an important part of the history to really recognize this.

Inflammatory bowel disease, and you all have in your books these charts. What’s important to remember about these conditions is their distribution and some of the pathological differences between them. It’s not an uncommon type of question to ask you, to be able to separate out the conditions. So just remember, typically ulcerative colitis shows continuous lesions from the rectum back to the cecum. Whereas Crohn’s disease is going to have what we call "skip" lesions and have more segmental type of disease. As a matter of fact, if you have Crohn’s disease involving the colon.

Ulcerative Colitis. Again, mild disease, salicylates and sulfasalazine. Again you use mesalamine enemas if the disease is confined to the left side of the colon. You use steroid enemas if mesalamine enemas fail. Systemic corticosteroids if everything else fails. If you go up to moderate disease, the first choice is corticosteroids, salicylates and sulfasalazine and its isomers, like Asacol and Pentasa are second choices.

Crohn’s disease. It’s really not much different than it is for ulcerative colitis. Chronic Crohn’s disease is managed in the same manner as ulcerative colitis. Small intestinal Crohn’s disease, corticosteroids are the first choice of therapy primarily because drugs like salicylase or sulfapyridine is only going to be absorbed in the terminal ileum and colon. So if you’ve got small intestinal Crohn’s disease you want a drug that is going to be absorbed in the location.

Vomiting. Again, what do we know about vomiting? Well, there’s acute vomiting, short term episodes of abrupt onset. You can have recurrent vomiting, three episodes in a three-month period of time, and you can have youngsters who vomit chronically. They have mild episodes that occur frequently and then you can have the so-called cyclic vomiting syndrome, which we will define a little bit more later, and discuss what that’s related to. If it’s associated with fever.

Constipation. This is more frequent in young boys than in young girls before puberty. But after puberty constipation is more frequent in females than in males. And I don’t think we really understand that yet, what the differences for that really is. There’s no question that many females during the period just before their menses become incredibly constipated and then they have diarrhea as menses begins. That’s not true of all girls but it is true of a large number.

Nutrition. There are five basic food groups, vegetables, fruits, grains, dairy products and the protein groups. What is an RDA? It won’t be uncalled for to see a question where they define it and you have to pick out the answer. "Levels for intakes for the central nutrients that, on the basis of scientific knowledge, are judged by the Food and Nutrition Board.

Let’s talk about the vitamins. Water soluble vitamins. These are the ones that are considered to be water soluble. So again it’s important to at least recognize them. The deficiency states with the water soluble vitamins; again, one of the typical things to recognize is that thiamin is associated with beriberi. And this is congestive heart failure, tachycardia, and peripheral edema. And the peripheral edema is believed to be associated with the congestive heart failure.

B12 deficiency; extremely unusual unless you have someone who has a congenital defect in absorption of B12. There’s a syndrome called Imerslund syndrome which is a congenital failure to be able to absorb vitamin B12 in the terminal ileum because they lack the binding sites in the terminal ileum for the B12.

Ascorbic acid deficiency, or scurvy. Again, these are the characteristics of it; poor wound healing, which is very similar to what you see in essential fatty acid deficiency. Be aware that bleeding problems, which also can be seen in essential fatty acid deficiency, are characteristic of it. Easy fracture of bones. Bleeding gingiva with loose teeth perhaps in the older child. So many of these conditions have overlaps between them and sometimes you are asked to show the similarities or the differences between them.

Niacin deficiency is probably the easiest; dermatitis, diarrhea and dementia. And the dermatitis is typically in areas where there has been exposure to the sun. So I used to have a picture of a child with pellagra and it’s disappeared, but it basically showed a youngster who had what looked like a necklace in the neck area and also on the wrist. This patient had sort of a reddish-magenta kind of eruption and that was due to niacin deficiency.

Folate deficiency. These patients get a macrocytic anemia. They are very much like patients with B12 deficiency. So they get big red blood cells, but different than patients with B12 deficiency syndrome, they get leukopenic, poor growth and gllossitis. Again, they have overlap with patients who have vitamin B and B2 deficiency, and also pyridoxine deficiency. Diarrhea is another characteristic of folate deficiency. The folate is very important for the integrity of the intestinal mucosa.

Now, biotin deficiency is one of the rarer types. Again, there is the overlap between this and the other vitamin B2, B6 deficiencies. Just be aware that they share some similar features.

What about toxicity states? Can you get vitamin poisoning? Would you be able to recognize vitamin poisoning if you saw it? There are only three water soluble vitamins which cause toxicity when given in excess; niacin, vitamin B6 and vitamin C. Know that. How would you know niacin toxicity? These are its characteristics.

Vitamin B6 toxicity. These are basically all neurological manifestations that are seen with it. Again, it would be an unusual phenomenon to see but it does occur. Probably vitamin C toxicity would be the commonest vitamin toxicity we might see, of the water soluble vitamins, in children because a lot of parents believe that vitamin C taken in high doses will prevent viral infections, will stimulate the immunity. Maybe it does, I don’t know, but there are considerable side effects from it; nausea, diarrhea.

There are four fat soluble vitamins, A, D, E and K. What are the signs of deficiency? The characteristics that you see with vitamin A deficiency, clinical presentation, night blindness. And the other thing is xerophthalmia where they get problems like scaly-ness of the eyelids is one of the characteristics of it because it affects the skin and affects the cornea of the patient. So the cornea tends to become irregular. They also have a general problem with their skin as a result of it.

Vitamin E deficiency. The clinical presentation here is hemolytic anemia in the premature infants, loss of neural integrity, neurological changes. These patients usually get problems, if you follow them, they have decreased reflexes if they get vitamin E deficiency. They then may have problems with sensory changes and have problems with positional sense.

Vitamin D toxicity. These are the characteristics of it; hypercalcemia, anorexia, vomiting and poor growth. Again, that is a pretty unusual occurrence in the general population.

Now a little bit about the trace metals. Zinc deficiency; there is a congenital syndrome we’ll talk about in a minute. How do you get zinc deficiency? Well zinc deficiency is usually associated with diarrhea. Patients who have chronic diarrhea with mucosal malabsorption are very prone to get zinc deficient. Patients with short bowel syndrome who are not managed effectively.

Patients who are zinc deficient will also have decreased appetite. Zinc deficiency has been recognized to be seen in patients with cystic fibrosis, but I do not think it is associated with the anorexia in that condition. And it will also affect growth failure. The congenital condition that people can be born with is called tacra-dermatitis enteropathica. It’s an autosomal recessive disorder in which there is a defect in zinc absorption. These patients will present, usually in the first six months of life.

Selenium deficiency. Selenium is another important trace element. Again, when do we see selenium deficiency? It’s seen in patients with chronic diarrhea, because it, like zinc, is typically absorbed in the duodenum and jejunum. So if you have someone where the mucosa in those areas is substantially injured or you’ve had a major intestinal resection, they may have substantial losses of this trace element. The manifestations are; they can myositis, cardiomyopathy and macrocytic anemia.

The only one I didn’t include is copper. Copper deficiency, as you know, can be associated with a couple of things. One, it can be associated with a microcytic anemia. Just remember that copper and iron are very closely related to each other and that copper is necessary for the reduction of ferric to ferrous iron.

Now we’ll talk a little about kwashiorkor and marasmus, because that is something that is very typically asked on the Board. Not that I know it’s going to be on, but it’s been on enough times that I know that you probably should be able to separate the two. Kwashiorkor results from a severe deficiency of protein, and less than adequate caloric intake. So patients with kwashiorkor more often than not will tend to look a bit fat or plump, because they are retaining a lot of fluid.