Malabsorption syndrome

　　Firstly, primary malabsorption syndrome

　　It is due to some defect or abnormality in the small intestinal mucosa (absorption cells), which affects the absorption and transport of nutrients through the mucosal epithelial cells. It includes celiac disease (coeliac disease) and tropical sprue (tropicsprue) and other diseases.

　　Secondly, secondary malabsorption syndrome

　　1. Indigestion

　　(1) Deficiency of pancreatic enzymes such as chronic pancreatitis, pancreatic cancer, pancreatic fibrocystic disease, pancreatic calculi, primary pancreatic atrophy, etc.

　　(2) Deficiency of bile salts such as diffuse liver damage, bile duct obstruction, biliary cirrhosis, intrahepatic cholestasis, ileal resection, excessive growth of bacteria in the intestine (intestinal contamination syndrome).

　　(3) Deficiency of intestinal mucosal enzymes such as congenital lactase deficiency.

　　2. Malabsorption

　　(1) Insufficient small intestinal absorption area such as excessive small intestinal resection (short bowel syndrome), gastrocolonic fistula, inappropriate gastrojejunal anastomosis, jejuno-colonic fistula, etc.

　　(2) Small intestinal mucosal lesions such as small intestinal inflammation, including infectious, radioactive, and drug-induced (neomycin colchicine, etc.); parasitic diseases, such as giardiasis, nematodes, etc.

　　(3) Lesions of the intestinal wall infiltration such as lymphoma, tuberculosis, Crohn's disease, Whipple's disease, etc.

　　(4) Small intestinal motility disorders such as tachycardia due to hyperthyroidism, which affects the absorption time of the small intestine, and bradycardia due to pseudo-obstruction of the small intestine, systemic sclerosis, leading to excessive growth of bacteria in the small intestine.

　　(5) Lymphatic blood flow disorders such as lymphatic hypoplasia, lymphatic obstruction (trauma, tumor, tuberculosis, etc.), and circulatory disorders (portal hypertension, congestive heart failure).

　　1. Disturbance of water and electrolytes This patient often has hypoproteinemia, an increase in total body fluid volume, making the extracellular fluid hypotonic. When vomiting and diarrhea occur, it is easy to cause hypotonic dehydration and severe electrolyte disorder, resulting in hypokalemia, hyp钠, hypocalcemia, and hypomagnesemia, causing corresponding symptoms.

　　2. Often accompanied by other nutrient deficiencies, especially vitamin A deficiency, which can cause dry and softening of the cornea of the eye, even perforation. It is also often accompanied by cheilitis caused by vitamin B deficiency. Due to slow growth and development, rickets is rare, and nutritional anemia often occurs.

　　Due to low systemic immune function, it is very easy to develop various acute and chronic infections and infectious diseases, especially intestinal and respiratory tract infections. It is easy to transmit infectious diseases such as measles and tuberculosis, and parasitic diseases. Intestinal or systemic fungal infections are also not uncommon. Once infection occurs, it often does not heal. Infections such as Gram-negative bacillary enteritis, sepsis, or urinary tract infection are often difficult to cure.

　　1. Diarrhea and other gastrointestinal symptoms

　　Diarrhea is the main symptom and the most characteristic, with 3-4 or more bowel movements per day, large fecal volume, non-formed, pale with greasy luster or foam, foul smell, can also be watery diarrhea. A few mild or atypical cases may not have diarrhea, accompanied by abdominal rumbling, bloating, abdominal discomfort, but rarely abdominal pain. Some patients may have loss of appetite and nausea, vomiting.

　　2. Symptoms of nutritional deficiency

　　After the onset of diarrhea, due to protein loss and insufficient heat supply, patients gradually feel fatigue, weight loss, and may appear anemia, lower limb edema, hypoproteinemia.

　　3. Symptoms of vitamin and electrolyte deficiency

　　Symptoms of varying degrees of various vitamin deficiencies or electrolyte deficiencies may occur, such as bone pain, tetany of hands and feet, even pathological fractures due to malabsorption of vitamin D and calcium; malabsorption of vitamin B group may cause glossitis, cheilitis, peripheral neuritis, etc.; malabsorption of vitamin B12, folic acid, and iron can cause anemia; insufficient potassium supplementation can exacerbate weakness, fatigue, oliguria, nocturia, etc.

　　There is no effective preventive measure for primary malabsorption syndrome. For malabsorption caused by biliary tract and pancreatic diseases, attention should be paid to the treatment of the primary disease. Improper handling of gastrointestinal surgery is also an important factor causing malabsorption, so the surgical wound should be handled with caution. In addition, it is also necessary to pay attention to the prevention of infections by parasites and others.

　　1. It is best to adopt a high-calorie, high-protein, high-vitamin, easy-to-digest, non-irritating low-fat diet.

　　2. Malabsorption syndrome is more common in the elderly, mainly related to the degenerative changes of the digestive system in the elderly. After entering the elderly period, the villi of the small intestine become shorter, the absorption area decreases, and the pancreas gradually atrophies, all of which can promote or exacerbate malabsorption syndrome.

　　3. Physical labor should be limited, and it is not advisable to live in a hot environment.

　　1. Fat balance test

　　Consume a test meal with more than 70g of fat daily for 6 consecutive days. After collection, measure the fat content in the feces 72 hours later (days 4-6) and calculate the absorption rate. Fat absorption rate = (intake fat in the last 3 days - fecal fat in the last 3 days) / (intake fat) × 100. Normal value: >95%, less than normal indicates fat absorption disorder.

　　2. D-xylose absorption test

　　D-Xylose is a pentose, after oral administration, it is not decomposed by digestive enzymes, absorbed directly through the jejunal mucosa, does not metabolize in the body, and is excreted by the kidney. If renal function is normal, the excretion of D-xylose in the urine can reflect the small intestinal absorption function. Method: take orally 5g of D-xylose on an empty stomach, collect urine for 5 hours, and measure the D-xylose in the urine. Normal value: >1.25g (25%), 1.0-1.2g is可疑.

　　3. Vitamin B12 absorption test

　　Reflecting the ileal absorption function, first inject vitamin B12 1000ug, to make the body saturated, take orally 60 cobalt-labeled vitamin B12 2ug, collect urine for 48 hours, measure the cobalt content, normal value: >8-10%, 2-7% indicates moderate malabsorption.

　　4. BT-PABA (also known as pancreatic function peptide) test

　　After oral administration of benzoyl-L-tyrosine-p-aminobenzoic acid (BT-PABA), it is decomposed by trypsin in the small intestine, and the free p-aminobenzoic acid is easily absorbed by the small intestine and excreted by the kidney. The amount excreted in 6 hours of urine can reflect the exocrine function of the pancreas. Normal value: 55~75％.

　　5. Barium meal X-ray examination of the entire gastrointestinal tract

　　It can understand the secretory and motor function of the small intestine and related lesions, such as intestinal dilatation, stricture, changes in mucosal folds, diverticula, fistula, etc.

　　1. High-protein, high-energy, low-fat semi-liquid or soft food, with more than 100g of protein per day, less than 40g of fat per day, and a total energy of 10.46MJ (2500kcal). Choose foods with low fat content and easy digestion, such as fish, chicken, egg whites, tofu, and skim milk. Plant oils should not be consumed excessively. For those with severe diarrhea, medium-chain fatty acids can be administered. For severe cases, intravenous hyperalimentation or elemental diet and slurry diet may be adopted to ensure energy and positive nitrogen balance.

　　In addition to supplementing sufficient vitamins through food, injections may be administered when necessary. Based on clinical symptoms, focus on supplementing the corresponding vitamins, such as vitamin A, complex vitamin B, vitamin C, vitamin D, vitamin K, etc.

　　For those with clear etiology, treatment should be targeted at the etiology, supplemented by symptomatic treatment; for those with unclear etiology, active symptomatic and supportive treatment should be carried out. For those with frequent diarrhea, antispasmodics or loperamide (also known as loperamide, a trade name for Imodium) can be administered to reduce the frequency of diarrhea. Adjust the diet, intravenously supplement nutrition, protein, various vitamins, and electrolytes. For example, intravenous infusion of fat emulsion, albumin, Vitalipid N (a milk emulsion containing vitamin A, D2, E, K1, etc.), Soluvit N (a water-soluble vitamin injection containing vitamin B1, B2, B6, niacin, pantothenic acid, vitamin C, H, B12, folic acid, etc.), and so on. In case of necessity, plasma or whole blood transfusion may be required.