Overview of Intestinal Malabsorption Syndrome

1. Samatbek Turdaliev

2. Tamboliya Shyam Kanjibhai

Aakif

(1. Teacher, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic

2. Students, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic.)

ABSTRACT

Malabsorption syndrome is a common yet complex pediatric condition characterized by impaired digestion and absorption of nutrients in the small intestine. It often results from abnormalities affecting carbohydrate, fat, or protein absorption. The disorder manifests clinically with diarrhea, abdominal distention, weight loss, growth failure, and multiple nutrient deficiencies, leading to complications such as anemia, hypoproteinemia, and bone disorders. Pathogenesis involves both primary and secondary causes—primary types are linked to genetic enzyme deficiencies such as lactase, sucrose-isomaltase, and glucose-galactose transport defects, while secondary forms arise from intestinal infections, chronic inflammation, or surgical alterations. Fat malabsorption (steatorrhea) and combined mucosal injury contribute to significant nutritional compromise. Diagnosis relies on a combination of clinical evaluation and laboratory investigations, including fecal analysis, hydrogen breath testing, D-xylose absorption, Schilling test, enzyme assays, and small intestinal biopsy. Treatment is guided by addressing the underlying cause, correcting nutritional deficiencies, and providing tailored dietary modifications such as lactose-free, low-fat, or elemental diets enriched with medium-chain triglycerides and hydrolyzed proteins. Enzyme replacement therapy, antibiotics, and probiotics serve as adjunct measures depending on etiology. Comprehensive management, involving early detection, appropriate diagnostic testing, and sustained nutritional support, markedly improves outcomes and quality of life among affected children.

INTRODUCTION

Intestinal malabsorption syndrome is a frequently occurring pediatric disease and represents a clinical syndrome resulting from a dysfunction in digestion and absorption in the small intestines and a failure to adequately absorb protein, fat, and carbohydrate. The key clinical symptoms and signs are diarrhea, abdominal distention, weight loss, and a deficiency of nutrients. The pathogenesis is quite complex and can arise from abnormalities within either the intestinal, mucosal, and transit phases in a meal to reach its final path. The pathologies are abnormal glucose absorption in response to disaccharidase deficiency, abnormal fat absorption in response to exocrine pancreatic dysfunction, and protein malabsorption in response to massive mucosal injury to intestinal tissues. The common symptoms of this condition are steatorrhea, hypoproteinemia, anemia, and complications arising from vitamin deficiency. There are two kinds of malabsorption syndrome: primary malabsorption syndrome and secondary malabsorption syndrome. The majority are acquired in response to intestinal infection, surgical procedures, and chronic diseases. To reach a diagnosis, relevant tests in a laboratory to some extent are stool examination, breath tests, and biopsies of either small intestinal mucosa. On all aspects to treat this condition, supporting nutritional and elemental diet changes have to occur. Due to advances in diagnosis and therapeutic equipment, pediatrics keeping to this index have revolved to a better extent.

General clinical presentations of malabsorption (1) Diarrhea: Diarrhea is frequently a prominent presenting symptom in malabsorption syndrome, owing to the effect of unabsorbed nutrients on the bowel. Carbohydrates are fermented in the colon and cause bloating and anorexia, while impaired absorption of water leads to frequent micturition. Pain is often associated with vague abdominal symptoms and metastatic hyperactive bowel sounds. There is abdominal pain in patients with chronic pancreatitis, intestinal obstruction, and intestinal ischemia. (2) Weight loss, fatigue, and edema: As a direct sequel to impaired absorption and appetite, there is associated weight loss, failure to thrive, fatigue, and weakness. There is malabsorption and malnutritional maldevelopment, cachexia, and even malabsorptive maldevelopment in malnourished infants and children. There is hypoproteinemia and peripheral edema in patients with malabsorptive protein loss and malabsorptive hypoproteinemia. There is dehydration, electrolyte imbalance, and acid-base disorders in patients with frequent diarrhea. In chronic patients, there is malabsorptive malnutritional maldevelopment, malabsorptive blood disorders, and malabsorptive growth failure. (3) Manifestations of malabsorptive vitamin and mineral disorders: There is iron deficiency anemia, and megaloblastic and macrocytic anemia in malabsorptive iron, folate, and vitamin B12 disorders. There is malabsorptive and hemorrhagic disorders in malabsorptive fat-soluble vitamin K and malabsorptive hypoprothrombinemic disorders. There is malabsorptive tetani in malabsorptive disorders of vitamin D, calcium, and magnesia. In patients with steatorrhea, there are pathologic and osteoporotic fractures and malabsorptive disorders. There is malabsorptive hyperparathyroidism and malabsorptive hypoplasia in malabsorptive hypo calcemic disorders. In malabsorptive disorders, there is malabsorptive blindness, malabsorptive and keratotic disorders, and malabsorptive and rough disorders.

Special presentations of malabsorption of key nutrients (1) Sugar malabsorption: In a normal body, lactose is hydrolyzed to glucose and galactose in the brush-border cells of the small intestinal mucosa after ingestion and is then absorbed. Due to various reasons, there is a reduction in lactase in the small intestinal mucosa, which makes it unable to hydrolyze and absorb lactose, a characteristic of milk, in its entirety in the small intestine and hence lactose malabsorption. Sugar malabsorption can be classified into two broad categories: primary and secondary. Conditions that cause primary malabsorption of sugars are lactose malabsorption in infants, sucrose isomaltase deficiency, and glucose-galactose malabsorption. Conditions that affect epithelial cells and brush border of the small intestinal mucus, like viral enteritis, chronic diarrhea, protein-calorie malabnostic, immuno-deficiency disorders, and post- small intestinal surgery, can all cause malabsorption of secondary 'sugars. (2) Fat malabsorption: The symptoms include diarrhea, abdominal distension, vomiting, and abdominal pain. The patient has a high quantity of steatorrheic stools, which are large in volume, pale in color, oily, and foul-smelling. Along with its malabsorption, it can cause emaciation, Nutritional anemia, hypo-proteinemia, stomatitis, Secondary defect of fat-soluble vitamins, and Growth inhibition. (3) Protein malabsorption: Pure malabsorption of proteins is introductive. Usually in combination with fat and or secondary malabsorption, where extensive destruction of intestinal mucus occurs. Symptoms include, Light colored stool smelling like rotten eggs, and those of hypoproteinemia syndrome like, edema.

Anything that can affect one or more of the three phases that occur in nutrient digestion and absorption—antral/hindgut graph-utical phase; intra-luminous phase; and transit phase terminology can cause malabsorption syndrome.

Sugar malabsorption is primarily due to a deficiency of a given disaccharidase in the small-intestinal mucosa, inhibiting the complete hydrolysis of disaccharides in food to monosaccharides. The absorption of monosaccharides is occasionally impaired as well. Deficiency of amylase is generally not pathologic and is found only in newborns. Sugar is nearly completely absorbed in the small intestine. However, a portion of this unavailable sugar passes to the colon and is degraded by intestinal flora (Bifidobacteria primarily and subsequently Lactobacilli, etc.) and is reabsorbed.

PATHOGENESIS

1. Primary Glucose Malabsorption: Of the primary malabsorption’s of glucose, congenital lactase deficiency, sucrose–isomaltase deficiency, and glucose-galactose malabsorption are autosomal recessive genetic disorders. The disorders are relatively rare and occur in all regions. The others occur in infancy after birth. In all disorders, histological examination of biopsies of the small intestine shows a normal histology but reduced activity of corresponding enzymes. In glucose-galactose malabsorption, activity of corresponding enzymes is normal. The malabsorption occurs due to a congenital deficiency of Na+-glucose and Na+-galactose carriers. The infants have a normal absorption of fructose.

2. Secondary lactase deficiency and malabsorption of monosaccharides are not uncommon in clinical practice. Secondary lactase deficiency can occur as a sequel to any infection that can injure the epithelial cells lining the small intestinal mucosa. Due to its presence in large amounts in the tip of the intestinal villi of the small intestine, lactase deficiency can occur when there is infection of the epithelial cells of the small intestinal mucosa. Secondary lactase deficiency can occur as a sequel to infection in the upper small intestine due to Acute enteritis, such as Rotaviral enteritis, infection with Giardia lamblia, etc., Chronic diarrhea, Protein-Calorie malnutrition, Immunodeficiency.

3. Fat malabsorption. Fat malabsorption is also known as steatorrhea. The condition is a syndrome that is brought about by inefficient digestion and absorption of fat. The syndrome can occur in different diseases. The steatorrhea that occurs as a result of intestinal disorders is always coupled with malabsorption of other substances. The condition is known as malabsorption syndrome.

4. Protein malabsorption: Protein malabsorption by itself is not common in clinical medicine. It is normally associated with extensive mucosal damage to the intestines and is often associated with fat malabsorption. diagnosis:1. The direct resulting symptoms are weight loss, growth retardation, pallor, and glossitis, abdominal distention, and discomfort due to increased gas. Diarrhea is frequent. When this is due to malabsorption of fats, stools are pale, soft, oily, frothy, profuse, and foul-smelling, sticking to the bowl and persisting despite flushing. Sudden diarrhea in infants within a few hours of milk ingestion, associated with distention and gas in abdomen, suggests lactase deficiency.2. The resulting symptoms of various deficiency disorders secondary to malabsorption depend on the extent and severity of malabsorption and vary depending on the extent and sites of involvement of the gastrointestinal tracts. Often associated are anemia, primarily iron deficiency (microcytic anemia) and deficiency of folic acid and vitamin B12 (macrocytic anemia); and nervous symptoms like restlessness, insomnia, and irritability. Deficiencies of vitamin D and calcium can occur, giving rise to seizures, tetany, and growth delays in bones and teeth. Deficiency of fat-soluble vitamin K can give rise to reduced prothrombin, and purpura and tendencies to bleeding. Deficit of riboflavin gives rise to glossitis and angular cheilitis. Protein malabsorption leads to protein-deficient hypoproteinemia edema, generally in lower extremities.3. The digestion and malabsorption in intestines due to some associated diseases have different resultant symptoms for those underlying diseases. There may, therefore, be jaundice secondary to obstruction, signs of infections, and malabsorption leading to resections of intestines.2. Investigations: Laboratory tests:1. Screening Test (1) Fecal pH determination: The pH in fresh feces in glucose-intolerant children is primarily below 6 and in some cases below 5.5 (2) Determination of reducing sugar in feces: Take 1 volume of fresh feces and mix it thoroughly with 2 volumes of water. After centrifugation, take 1ml of the supernatant and add 1 Clinitest tablet. Then estimate the reducing sugar concentration based on the colorimetry technique in comparison with a card. Saturations above 0.5g/dl are considered to be positive. Values above 0.75g/dl are considered to be pathological in newborn babies. The supernatant can also be heated to estimate the reducing sugar concentration through Benedict's solution added to the above-mentioned supernatant.2. Sugar-Expiratory Test: Sugar-Expiratory Test is a sensitive and reliable technique but needs gas chromatography to estimate hydrogen exhaled. The human body has no capability to produce its own hydrogen; but all of it in exhaled air originates from bacterial fermentation in the colon. In a normal individual, all potentially absorbed sugars will have to reach an absorption site above the colon in an absorbed state. The unabsorbed amounts fermented in bacterial colon can yield only hydrogen in human exhaled air. The same finding can be made for malabsorptive disorders in the small intestines.3. Small intestinal biopsies can be obtained either via endoscopic biopsy through a Crosby intestinal biopsy catheter placed orally. The biopsy under negative pressure often provides a thin slice of intestinal mucus. The biopsy is of immense value in diagnosing Congenital Nutritional Deficiency.4. The D-xylose absorption test: In cases where renal function is satisfactory. The diffusion of xylose is determined in urine. The test is based on absorption properties of a portion of small intestines. The positive odds ratio for a patient undergoing malabsorption due to extensive injury to mucus membranes of small intestines exceeds 70%. The same is negative in case of pancreatic disorders and disorders localized to Ileum. The testing is not positive in patients having impaired renal clearance and in patients with delayed gastric emption. Test procedure: Take 5g of dextroxylose given in 250ml. Take it on an empty stomach and follow it with 200-300ml of water. The urine is collected and examined for its xylose concentration.

Normal value: (1.51±0.21)g. Suggestive excretion is 1-1.16g. If <1g is excreted, it is an abnormality. Due to difficulty in urine acquisition in infants and young children, blood xylose can be assayed. In this assay, a concentration <200mg/L is considered malabsorption.5. Vitamin B12 absorption test/Schilling test: Initially, 1 mg of vitamin B12 is given intramuscularly to fill the body stores. Subsequently, 2 μg of vitamin B12 labeled either with 60Co (Cobalt) or 57Co is given orally. The urine is collected for 24 hours. The activity present in this urine is to be measured. In a normal individual, this is to be 8% to 10% more than that given in oral form. Less than that indicates malabsorption. The tests are applied in malabsorption associated with terminal ileum malabsorption and surgical resection of the terminal ileum; and in blind loop syndrome and pernicious anemia caused by a deficiency of intrinsic factors.6. 14C-glycocholic acid expiratory test: Oral intake of 370 MBq (10 mCi) of 14C-glycocholic acid is given. In a normal individual, this is largely absorbed in the ileum and is discharged through the hepatobiliary ducts to reach the small intestine. Only a small portion enters into the large intestine and is excreted as feces. The rest is converted to 14CO2. In a normal individual, within 4 hours post-oral intake of 14C-glycocholic acid in a concentration <1% of total intake is exhaled. In 24 hours, its excretion in feces is less than 8%. The excretion in 14CO2 within a 4 hour period is increased in a patient with bacterial overgrowth in small intestines and in those in whom terminal and/or jejunal lesions and/or surgical resection has developed.7. Examination of fluids: Flüssigkeit is obtained through a cannula in duodenum and/or jejunums for examination and/or bacterial culture. The activity of enzymes present in fluids is measured.8. Sweat chlorine determination: Sweat chlorine concentration is required. In pancreatic cystic fibroses, a level above 60 mmol/L is valuable.9. In glucose tolerance tests, including others like that mentioned above, a glucose level of 2g/kg is given.

The flat glucose tolerance curve indicates malabsorption. But blood glucose can vary for a number of reasons. The tests can only be interpreted in relation to clinical findings. The chromatography technique can analyze fecal glucose concentration and distinguish between various types of glucose. Lead acetate technique is employed to estimate the level of lactose in feces. The techniques mentioned above are all useful in diagnosis.

TREATMENT

Principles of Treatment: The principles entail addressing the underlying cause and making nutritional corrections.

1. Etiological treatment

(1) Stop eating foods for which you have an intolerance: If you are lactose intolerant, you need to stop consuming lactose.

(2) Fill a deficiency in digestive enzymes. Examples are lactase for lactose malabsorption and pancreatic enzymes for pancreatic insufficiency.

(3) Antibiotic medicine can be considered as and when required for chronic enteritis due to bacterial infection, and as and when required, probiotics can also be considered. The symptoms can be made to alleviate when and if the cause

2. Nutritional therapy will primarily include high caloric, high protein, and low fat diets. The patient will mainly have anorexia and poor digestion and absorption. Moreover, food and medications will come out whole within their stools. In this event, intravenous nutrition will first be considered. Once signs and symptoms have resolved, a switch will occur to an elemental diet. The diet will mainly include easily digestible and partially digested foods. The fat will come from medium-chain triglycerides. Carbohydrates will come from maltodextrin and glucose. The protein will come from hydrolyzed protein and amino acids. Frequent feeds will mainly occur. Advances will gradually happen. Lactose-free milk power and hydrolyzed proteinelemental diets are some other sources.

3. Symptomatic treatment (1) To provide supplements of vital vitamins and minerals. (2) Timely correction of water and electrolyte as well as acid-base imbalance: The theoretical basis for this treatment is very simple. The therapy will work as long as an offending list of disaccharides and/or monosaccharides is eliminated. But in actual practice, there are some specific challenges to this as to how a diet can actually address this requirement and how much reduction is required in sugar intake in order to keep this child asymptomatic. For congenital glucose and galactose malabsorption, unsweetened soy milk with about 5% fructose added can be given. The child's absorption function often recovers after 2-3 years of age, and they can tolerate small amounts of starch and lactose. However, the extent to which starchy and lactose- containing foods can be added requires joint effort and repeated trials by the doctor and family. For sucrose - isomaltose malabsorption, sucrose should be restricted from childhood to prevent symptoms. If sucrose is not added to dairy products, glucose can be used as a substitute. Syrup-containing medications should also be avoided. As the child grows, the strict restriction on sucrose can be gradually relaxed, but repeated trials are necessary. Generally, starch does not need to be restricted because starch contains very little branched oligosaccharides with 1,6 glycosidic bonds.

REFERENCES

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