Malabsorption Syndrome

Definition

Malabsorption syndrome is an alteration in the ability of the intestine to absorb nutrients adequately into the bloodstream. It may refer to malabsorption of one specific nutrient or for specific carbohydrates, fats, or trace elements (micronutrients).

Causes and symptoms

Protein, fats, and carbohydrates (macronutrients) normally are absorbed in the small intestine; the small bowel also absorbs about 80% of the eight to ten liters of fluid ingested daily. There are many different conditions that affect fluid and nutrient absorption by the intestine. A fault in the digestive process may result from failure of the body to produce the enzymes needed to digest certain foods. Congenital structural defects or diseases of the pancreas, gall bladder, or liver may alter the digestive process. Inflammation, infection, injury, or surgical removal of portions of the intestine may also result in absorption problems; reduced length or surface area of intestine available for fluid and nutrient absorption can result in malabsorption. Radiation therapy may injure the mucosal lining of the intestine, resulting in diarrhea that may not become evident until several years later. The use of some antibiotics can also affect the bacteria that normally live in the intestine and affect intestinal function.

Risk factors for malabsorption syndrome include:

• premature birth
• family history of malabsorption or cystic fibrosis
• use of certain drugs, such as mineral oil or other laxatives
• travel to foreign countries
• intestinal surgery, including bowel transplantation
• excess alcohol consumption.

The most common symptoms of malabsorption include:

• Anemia, with weakness and fatigue due to inadequate absorption of vitamin B₁₂, iron, and folic acid
• Diarrhea, steatorrhea (excessive amount of fat in the stool), and abdominal distention with cramps, bloating, and gas due to impaired water and carbohydrate absorption, and irritation from unabsorbed fatty acids. The individual may also report explosive diarrhea with greasy, foul-smelling stools.
• Edema (fluid retention in the body's tissues) due to decreased protein absorption
• Malnutrition and weight loss due to decreased fat, carbohydrate, and protein absorption. Weight may be 80-90% of usual weight despite increased oral intake of nutrients.
• Muscle cramping due to decreased vitamin D, calcium, and potassium levels
• Muscle wasting and atrophy due to decreased protein absorption and metabolism
• Perianal skin burning, itching, or soreness due to frequent loose stools.

Irregular heart rhythms may also result from inadequate levels of potassium and other electrolytes. Blood clotting disorders may occur due to a vitamin K deficiency. Children with malabsorption syndrome often exhibit a failure to grow and thrive.

Several disorders can lead to malabsorption syndrome, including cystic fibrosis, chronic pancreatitis, lactose intolerance, and gluten enteropathy (nontropical sprue.)

Tropical sprue is a malabsorptive disorder that is uncommon in the United States, but seen more often in people from the Caribbean, India, or southeast Asia. Although its cause is unknown, it is thought to be related to environmental factors, including infection, intestinal parasites, or possibly the consumption of certain food toxins. Symptoms often include a sore tongue, anemia, weight loss, along with diarrhea and passage of fatty stools.

Whipple's disease is a relatively rare malabsorptive disorder, affecting mostly middle-aged men. The cause is thought to be related to bacterial infection, resulting in nutritional deficiencies, chronic low-grade fever, diarrhea, joint pain, weight loss, and darkening of the skin's pigmentation. Other organs of the body may be affected, including the brain, heart, lungs, and eyes.

Short bowel syndromes—which may be present at birth (congenital) or the result of surgery—reduce the surface area of the bowel available to absorb nutrients and can also result in malabsorption syndrome. Congenital short bowel syndrome occurs in about 24 out of 100,000 live births and has a high mortality rate (about 38%).

Diagnosis

The diagnosis of malabsorption syndrome and identification of the underlying cause can require extensive diagnostic testing. The first phase involves a thorough medical history and physical examination by a physician, who will then determine the appropriate laboratory studies and x rays to assist in diagnosis. A 72-hour stool collection may be ordered for fecal fat measurement; increased fecal fat in the stool collected indicates malabsorption. A biopsy of the small intestine may be done to assist in differentiating between malabsorption syndrome and small bowel disease. Ultrasound, computed tomography scan (CT scan), magnetic resonance imaging (MRI), barium enema, or other x rays to identify abnormalities of the gastrointestinal tract and pancreas may also be ordered.

A newer method of obtaining diagnostic information about the small intestine was approved by the Food and Drug Administration (FDA) in 2001. Known as the M2A Imaging System, the device was developed by a company in Atlanta, Georgia. The M2A system consists of an imaging capsule, a portable belt-pack image receiver and recorder, and a specially modified computer. The patient swallows the capsule, which is the size of a large pill. A miniature lens in the capsule transmits images through an antenna/transmitter to the belt-pack receiver, which the patient wears under ordinary clothing as he or she goes about daily activities. The belt-pack recording device is returned after seven or eight hours to the doctor, who then examines the images recorded as a digital video. The capsule itself is simply allowed to pass through the digestive tract.

Preparation requires only fasting the night before the M2A examination and taking nothing but clear liquids for two hours after swallowing the capsule. After four hours the patient can eat food without interfering with the test. As of the early 2000s, the M2A system is used to evaluate gastrointestinal bleeding from unknown causes, inflammatory bowel disease, some malabsorption syndromes, and to monitor surgical patients following small-bowel transplantation.

Laboratory studies of the blood may include:

• Serum cholesterol. May be low due to decreased fat absorption and digestion.
• Serum sodium, potassium, and chloride. May be low due to electrolyte losses with diarrhea.
• Serum calcium. May be low due to vitamin D and amino acid malabsorption.
• Serum protein and albumin. May be low due to protein losses.
• Serum vitamin A and carotene. May be low due to bile salt deficiency and impaired fat absorption.
• D-xylose test. Decreased excretion may indicate malabsorption.
• Schilling test. May indicate malabsorption of vitamin B₁₂.

Treatment

Fluid and nutrient monitoring and replacement is essential for any individual with malabsorption syndrome. Hospitalization may be required when severe fluid and electrolyte imbalances occur. Consultation with a dietitian to assist with nutritional support and meal planning is helpful. If the patient is able to eat, the diet and supplements should provide bulk and be rich in carbohydrates, proteins, fats, minerals, and vitamins. The patient should be encouraged to eat several small, frequent meals throughout the day, avoiding fluids and foods that promote diarrhea. Intake and output should be monitored, along with the number, color, and consistency of stools.

The individual with malabsorption syndrome must be monitored for dehydration, including dry tongue, mouth and skin; increased thirst; low, concentrated urine output; or feeling weak or dizzy when standing. Pulse and blood pressure should be monitored, observing for increased or irregular pulse rate, or hypotension (low blood pressure). The individual should also be alert for signs of nutrient, vitamin, and mineral depletion, including nausea or vomiting ; fissures at corner of mouth; fatigue or weakness; dry, pluckable hair; easy bruising; tingling in fingers or toes; and numbness or burning sensation in legs or feet. Fluid volume excess, as a result of diminished protein stores, may require fluid intake restrictions. The physician should also be notified of any shortness of breath.

Other specific medical management for malabsorption syndrome is dependent upon the cause. Treatment for tropical sprue consists of folic acid supplements and long-term antibiotics. Depending on the severity of the disorder, this treatment may be continued for six months or longer. Whipple's disease also may require long-term use of antibiotics, such as tetracycline. Management of some individuals with malabsorption syndrome may require injections of vitamin B₁₂ and oral iron supplements. The doctor may also prescribe enzymes to replace missing intestinal enzymes, or anti-spasmodics to reduce abdominal cramping and associated diarrhea. People with cystic fibrosis and chronic pancreatitis require pancreatic supplements. Those with lactose intolerance or gluten enteropathy (nontropical sprue) will have to modify their diets to avoid foods that they cannot properly digest.

Prognosis

The expected course for the individual with malabsorption syndrome varies depending on the cause. The onset of symptoms may be slow and difficult to diagnose. Treatment may be long, complicated, and changed often for optimal effectiveness. Patience and a positive attitude are important in controlling or curing the disorder. Careful monitoring is necessary to prevent additional illnesses cause by nutritional deficiencies.

KEY TERMS

Anemia— A decrease in the number of red blood cells in the bloodstream, characterized by pallor, loss of energy, and generalized weakness.

Atrophy— A wasting away of a tissue or organ, often because of insufficient nutrition.

Biopsy— A tissue sample removed from the body for examination under the microscope.

Cystic fibrosis— A hereditary genetic disorder that occurs most often in Caucasians. Thick, sticky secretions from mucus-producing glands cause blockages in the pancreatic ducts and the airways.

Edema— From the Greek word meaning swelling, an excessive accumulation of fluid in the tissue spaces. Excessive generalized edema may also be referred to as ascites.

Gluten enteropathy— A hereditary malabsorption disorder caused by sensitivity to gluten, a protein found in wheat, rye, barley, and oats. Also called non-tropical sprue or celiac disease.

Intestines— The intestines, also known as the bowels, are divided into the large and small intestines. They extend from the stomach to the anus.

Short bowel syndrome— A condition in which the bowel is not as long as normal, either because of surgery or because of a congenital defect. Because the bowel has less surface area to absorb nutrients, it can result in malabsorption syndrome.

Steatorrhea— An excessive amount of fat in the stool.

Trace elements— A group of elements that are present in the human body in very small amounts but are nonetheless important to good health. They include chromium, copper, cobalt, iodine, iron, selenium, and zinc. Trace elements are also called micronutrients.

Resources

BOOKS

Beers, Mark H., MD, and Robert Berkow, MD, editors. "Malabsorption Syndromes." Section 3, Chapter 30. In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.

PERIODICALS

Adler, Douglas J., MD, and Christopher J. Gostout, MD. "Wireless Capsule Endoscopy." Hospital Physician May 2003: 17-22.

Forsberg, G., A. Fahlgren, P. Horstedt, et al. "Presence of Bacteria and Innate Immunity of Intestinal Epithelium in Childhood Celiac Disease." American Journal of Gastroenterology 99 (May 2004): 905-906.

Kumar, N., and P. A. Low. "Myeloneuropathy and Anemia Due to Copper Malabsorption." Journal of Neurology 251 (June 2004): 747-749.

Sabharwal, G., P. J. Strouse, S. Islam, and N. Zoubi. "Congenital Short-Gut Syndrome." Pediatric Radiology 34 (May 2004): 424-427.

Thompson, B. F., L. C. Fry, C. D. Wells, et al. "The Spectrum of GI Strongyloidiasis: An Endoscopic-Pathologic Study." Gastrointestinal Endoscopy 59 (June 2004): 906-910.

Wales, P. W., N. de Silva, J. Kim, et al. "Neonatal Short Bowel Syndrome: Population-Based Estimates of Incidence and Mortality Rates." Journal of Pediatric Surgery 39 (May 2004): 690-695.

ORGANIZATIONS

National Digestive Diseases Information Clearinghouse. 2 Information Way, Bethesda, MD 20892-3570. (800) 891-5389. Fax: (703) 738-4929. 〈http://digestive.niddk.nih.gov〉.

Malabsorption Syndrome

Definition

Malabsorption syndrome is an alteration in the ability of the intestine to absorb nutrients adequately into the bloodstream.

Causes and symptoms

Protein, fats, and carbohydrates (macronutrients) normally are absorbed in the small intestine; the small bowel also absorbs about 80% of the 8.4-10.5 quarts (8-10 liters) of fluid ingested daily. There are many different conditions that affect fluid and nutrient absorption by the intestine. A fault in the digestive process may result from failure of the body to produce the enzymes needed to digest certain foods. Congenital structural defects or diseases of the pancreas, gall bladder, or liver may alter the digestive process. Inflammation, infection, injury, or surgical removal of portions of the intestine may also result in absorption problems; reduced length or surface area of intestine available for fluid and nutrient absorption can result in malabsorption. Radiation therapy may injure the mucosal lining of the intestine, resulting in diarrhea that may not become evident until several years later. The use of some antibiotics can also affect the bacteria that normally live in the intestine and affect intestinal function.

Risk factors for malabsorption syndrome include:

• family history of malabsorption or cystic fibrosis

• use of certain drugs such as mineral oil or other laxatives
• travel to foreign countries, which may introduce parasites into the body
• intestinal surgery
• excess alcohol consumption

Individuals may experience symptoms of malabsorption, the most common of which include:

• anemia, with weakness and fatigue due to inadequate absorption of vitamin B₁₂, iron, and folic acid
• diarrhea (sometimes explosive diarrhea with greasy, foul-smelling stools), steatorrhea (excessive amount of fat in the stool), and abdominal distention with cramps, bloating, and gas due to impaired water and carbohydrate absorption, and irritation from unabsorbed fatty acids
• edema (fluid retention in the body's tissues) due to decreased protein absorption
• malnutrition and weight loss due to decreased fat, carbohydrate, and protein absorption; weight may be 80-90% of usual weight despite increased oral intake of nutrients
• muscle cramping due to decreased vitamin D, calcium, and potassium levels
• muscle wasting and atrophy due to decreased protein absorption and metabolism
• perianal skin burning, itching, or soreness due to frequent loose stools

Irregular heart rhythms may also result from inadequate levels of potassium and other electrolytes. Blood clotting disorders may occur due to a vitamin K deficiency. Children with malabsorption syndrome often exhibit a failure to grow and thrive.

Several disorders can lead to malabsorption syndrome, including cystic fibrosis, chronic pancreatitis, lactose intolerance, and celiac disease (gluten enteropathy, non-tropical sprue).

Tropical sprue is a malabsorptive disorder that is uncommon in the United States, but seen more often in people from the Caribbean, India, or southeast Asia. Although its cause is unknown, the disorder is thought to be related to environmental factors, including infection, intestinal parasites, or possibly the consumption of certain food toxins. Symptoms often include a sore tongue, anemia, weight loss, along with diarrhea and passage of fatty stools.

Celiac disease, also known as non-tropical sprue, gluten enteropathy, or celiac sprue, is an inherited disorder resulting in malabsorption because of an allergic reaction after consumption of a protein called gluten. Gluten is found in wheat, rye, barley, and oats.

Whipple's disease is a relatively rare malabsorptive disorder that affects mostly middle-aged men. The cause of the disorder is possibly related to bacterial infection, resulting in nutritional deficiencies, chronic low-grade fever, diarrhea, joint pain, weight loss, and darkening of the skin's pigmentation. Other organs of the body may be affected, including the brain, heart, lungs, and eyes.

Short bowel syndromes—which may be present at birth (congenital) or the result of surgery—reduce the surface area of the bowel available to absorb nutrients and can also result in malabsorption syndrome.

Bacterial overgrowth that is triggered by intestinal diverticulosis, intestinal disorders, blind loops, fistulas, and strictures may cause malabsorption, resulting in fat malabsorption and flatulence.

Intestinal lymphangiectasia, also called idiopathic hypoproteinemia, is a disorder affecting children and young adults in which the lymph vessels supplying the lining of the small intestine become enlarged. Lymph vessel enlargement may be a birth defect or may have been due to inflammation of the pancreas, called pancreatitis or a condition called constrictive pericarditis, which is characterized by a stiffening of the sac around the heart (constrictive pericarditis). These conditions increase pressure on the lymphatic system. Symptoms of intestinal lymphangiectasia are severe edema, and perhaps nausea, vomiting, mild diarrhea, fatty stools, and abdominal pain. The number of lymphocytes in the blood may decrease. As well, cholesterol and protein levels in the blood are low.

Diagnosis

Doctors often suspect malabsorption syndromes when weight loss, diarrhea, and nutritional deficiencies occur despite eating a healthy and adequate diet. The diagnosis of malabsorption syndrome and identification of the underlying cause can require extensive diagnostic testing.

The first phase of diagnosis involves a thorough medical history and physical examination by a physician, who will then determine the appropriate laboratory studies and x rays. A 72-hour stool collection may be ordered for fecal fat measurement; increased fecal fat in the stool indicates malabsorption. A biopsy of the small intestine may be done to assist in differentiating between malabsorption syndrome and small bowel disease. Pancreatic function tests are often conducted since pancreatic disorders are a common cause of malabsorption syndromes. Ultrasound, computed tomography scan (CT scan), magnetic resonance imaging (MRI), barium enema, or other x rays to identify abnormalities of the gastrointestinal tract and pancreas may also be ordered.

To diagnose intestinal lymphangiectasia, an intravenous injection of radioactive-labeled albumin may be ordered. Excessive protein is lost if abnormal amounts of the radioactive substance appear in the stool. Enlarged lymph vessels are indicated by a biopsy of the small intestine.

Laboratory studies of the blood may include:

• Serum cholesterol: May be low due to decreased fat absorption and digestion.
• Serum sodium, potassium, and chloride: May be low due to electrolyte losses with diarrhea.
• Serum calcium: May be low due to vitamin D and amino acid malabsorption.
• Serum protein and albumin: May be low due to protein losses.
• Serum vitamin A and carotene: May be low due to bile salt deficiency and impaired fat absorption.
• D-xylose test: Decreased excretion may indicate malabsorption.
• Schilling test: May indicate malabsorption of vitamin B₁₂.

Treatment

Fluid and nutrient monitoring and replacement is essential for any individual with malabsorption syndrome. Hospitalization may be required when severe fluid and electrolyte imbalances occur. Consultation with a dietitian to assist with nutritional support and meal planning is helpful. If the patient is able to eat, the diet and supplements should provide bulk and be rich in carbohydrates, proteins, fats, minerals, and vitamins. The patient should be encouraged to eat several small meals throughout the day, avoiding fluids and foods that promote diarrhea. Intake and output should be monitored, along with the number, color, and consistency of stools.

The individual with malabsorption syndrome must be monitored for dehydration, including dry tongue, mouth, and skin; increased thirst; low, concentrated urine output; or feeling weak or dizzy when standing. Pulse and blood pressure should be monitored for increased or irregular pulse rate, or hypotension (low blood pressure). The individual should also be alert for signs of nutrient, vitamin, and mineral depletion, including nausea or vomiting; fissures at corner of mouth; fatigue or weakness; dry, thinning hair; easy bruising; tingling in fingers or toes; and numbness or burning sensation in legs or feet. Fluid volume excess, as a result of diminished protein stores, may require fluid intake restrictions. The physician should also be notified of any shortness of breath.

Other specific medical management for malabsorption syndrome is dependent upon the cause. Treatment for tropical sprue consists of folic acid supplements and long-term antibiotics. Depending on the severity of the disorder, this treatment may be continued for six months or longer. Whipple's disease also may require long-term use of antibiotics such as tetracycline. Management of some individuals with malabsorption syndrome may require injections of vitamin B₁₂ and oral iron supplements. The doctor may also prescribe enzymes to replace missing intestinal enzymes, or antispasmodics to reduce abdominal cramping and associated diarrhea. People with cystic fibrosis and chronic pancreatitis require pancreatic supplements. Those with lactose intolerance or gluten enteropathy will have to modify their diets to avoid foods that they cannot properly digest.

Intestinal lymphangiectasia is treated by correcting the cause of the lymph vessel enlargement. For instance, treating constrictive pericarditis may relieve pressure on the lymph vessels. Some people improve by eating a low-fat diet and taking supplements of certain triglycerides, which are absorbed directly into the blood and not through the lymph vessels. If only a small part of the intestine is affected, it can be removed surgically.

Prognosis

The expected course for the individual with malabsorption syndrome varies, depending on the cause. The onset of symptoms may be slow and difficult to diagnose. Treatment may be long, complicated, and changed often for optimal effectiveness. Patience and a positive attitude are important in controlling or curing the disorder.

Health care team roles

The health care team should familiarize patients with their condition and the methods of dealing most effectively with their malabsorption syndrome. Physicians will typically take charge of the patient's care, ordering tests and medications. Nurses are involved in the daily care of the patient, including administering medicines. Clinical laboratory scientists and medical technologists peform laboratory tests on blood or fecal samples. Radiologic technologists perform many of the imaging studies used in diagnosis.

Prevention

Many malabsorption syndromes are hereditary. Genetic screening may prevent passing on the genes to unborn children. For infants or children, the best means of prevention of some of these hereditary conditions are by early detection at routine well-baby examinations and periodic follow-ups with school-aged and adolescent children. In some cases, however, prevention of malabsorption syndromes can consist of simply avoiding foods or substances that cause the patient an allergic reaction and/or gastrointestinal distress. Careful monitoring is necessary to prevent additional illnesses caused by nutritional deficiencies. Impure water sources should be avoided when traveling to prevent parasitic infection.

KEY TERMS

Anemia— A decrease in the number of red blood cells in the bloodstream, characterized by pallor, loss of energy, and generalized weakness.

Atrophy— A wasting away of a tissue or organ, often caused by insufficient nutrition.

Biopsy— A tissue sample removed from the body for examination under the microscope.

Constrictive pericarditis— A condition that is characterized by a stiffening of the sac around the heart, which leads to increased pressure on the lymphatic system.

Cystic fibrosis— A hereditary genetic disorder that occurs most often in Caucasians. Thick, sticky secretions from mucus-producing glands cause blockages in the pancreatic ducts and the airways.

Edema— An excessive accumulation of fluid in the tissue spaces.

Gluten enteropathy— A hereditary malabsorption disorder caused by sensitivity to gluten, a protein found in wheat, rye, barley, and oats; also called non-tropical sprue or celiac disease.

Intestines— Also known as the bowels; intestines are divided into the large and small intestines, extending from the stomach to the anus.

Short bowel syndrome— A condition in which the bowel is not as long as normal, either because of surgery or because of a congenital defect.

Steatorrhea— An excessive amount of fat in the stool.

Resources

BOOKS

Institute of Medicine. Dietary Reference Intakes: Applications in Dietary Assessment. Washington, D. C.: National Academy Press, 2001.

Institute of Medicine. Dietary Reference Intakes: Risk Assessment (Compass Series). Washington, D. C.: National Academy Press, 1999.

Larson-Duyff, Roberta. The American Dietetic Association's Complete Food & Nutrition Guide. New York: John Wiley & Sons, 1998.

Kelsen, David, Bernard Levin, and Joel Tepper. Principles and Practice of Gastrointestinal Oncology. Philadelphia: Lippincott Williams & Wilkins Publishers, 2001.

Mahan, L. Kathleen, and Sylvia Escott-Stump. Krause's Food, Nutrition, & Diet Therapy. London: W. B. Saunders Co., 2000.

Monahan, Frances, and Marianne Neighbors. Medical-Surgical Nursing: Foundations for Clinical Practice. Philadelphia: W. B. Saunders Co., 1998.

Rodwell-Williams, Sue. Essentials of Nutrition and Diet Therapy.) London: Mosby-Year Book, 1999.

Speakman, Elizabeth, and Norma Jean Weldy. Body Fluids and Electrolytes, 8th ed. London: Mosby Incorporated, 2001.

PERIODICALS

Jeppesen, Palle B., et al. "Differences in Essential Fatty Acid Requirements by Enteral and Parenteral Routes of Administration in Patients with Fat Malabsorption." American Journal of Clinical Nutrition (1999): 70: 78-84.

Misbah, S.A., and N. P. Mapstone. "Whipple's Disease Revisited." Journal of Clinical Pathology (2000): 53: 750-55.

Murphy, Jane, et al. "Fat Malabsorption in Cystic Fibrosis Patients." American Journal of Clinical Nutrition 1999): 70: a943-a944.

ORGANIZATIONS

American Dietetic Association. 216 W. Jackson Blvd., Chicago, IL 60606-6995. (312) 899-0040. 〈http://www.eatright.org/〉.

Food and Nutrition Information Center Agricultural Research Service, USDA. National Agricultural Library, Room 304, 10301 Baltimore Avenue, Beltsville, MD 20705-2351. (301) 504-5719. (301) 504-6409. 〈http://www.nal.usda.gov/fnic/〉. fnic@nal.usda.gov.

malabsorption (mal-ăb-sorp-shŏn) n. a state in which absorption by the small intestine of one or more substances, such as fat, vitamins, or amino acids, is reduced. Symptoms (depending on the substances involved) include weight loss, diarrhoea, anaemia, swelling (oedema), and vitamin deficiencies. The commonest causes are coeliac disease, pancreatitis, cystic fibrosis, blind-loop syndrome, or surgical removal of a length of small intestine.

malabsorption syndrome Defect of absorption of one or more nutrients; signs include diarrhoea, steatorrhoea, abdominal distension, weight loss, and specific signs of nutrient deficiency.