Home > Encyclopedia of Nursing & Allied Health > 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 qt (8–10 l) 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 pan-

creatic 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 lowfat 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.

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KEY TERMS

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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.

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Crystal Heather Kaczkowski, M.Sc.