malabsorption article


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Posted by c [2694.8205] on November 09, 2011 at 12:41:41:


Malabsorption

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What is malabsorption?

Malabsorption is a condition caused by the decreased ability to digest and/or absorb nutrients from food. It is seen with a variety of diseases and can lead to general malnutrition or to symptoms associated with deficiencies in specific nutrients.

The body requires a steady supply of nutrients to build, repair, and maintain itself, to produce energy, enzymes, hormones, proteins, cells, tissues and bone, and to fight infections. Nutrients come from the diet and include many essential vitamins and minerals (micronutrients).

Food that is eaten is digested in three stages:

Proteins, fats, and complex sugars (carbohydrates) are broken down by stomach acids, enzymes produced by the pancreas, and bile from the liver. This process also releases micronutrients.
Nutrients are absorbed primarily by cells in the small intestines.
Nutrients are transported throughout the body and used or stored.
Any disruption or interference with this process can lead to malabsorption. The type and severity of deficiencies seen and the symptoms experienced depend on whether the problem affects general digestion and absorption or affects one or more specific nutrient.

Digestive problems
Fat, proteins and carbohydrates cannot be properly digested without bile and pancreatic enzymes. Insufficiencies in these substances can occur, for example, with liver and pancreatic diseases that limit their production, and with conditions such as cystic fibrosis that prevent pancreatic enzymes from getting to the digestive tract.

Absorption problems
If the intestines are unable to or prevented from absorbing nutrients, then the nutrients are eliminated from the body in the stool. This can happen when there is damage to the intestinal cells and tissues or when the intestines have been shortened, such as due to surgery, reducing the surface area and the amount of time available in which nutrients can be absorbed from food as it passes through the digestive tract.

As an example of a specific deficiency, vitamin B12 absorption requires both stomach acid and intrinsic factor, a substance produced by parietal cells in the stomach. Stomach acid separates B12 from proteins and intrinsic factor binds with B12. A lack of either one prevents intestinal absorption and can lead to vitamin B12 deficiency. This can happen with advancing age, with medications that suppress stomach acid production, with gastric bypass surgeries, and with diseases that damage parietal cells or cause general malabsorption.

Transport problems
Once absorbed in the intestines, nutrients may be hindered from being transported throughout the body. This may be caused by problems with the lymphatic system such as lymphoma or the rare inherited disorder, abetalipoproteinemia.

Within these categories, there are a number of conditions and diseases that can cause malabsorption and the associated signs and symptoms. Below is a list of just some of these:

Narrowing, closure or absence of bile ducts (biliary atresia) or blockage of bile flow (cholestasis) causing a lack of bile for digestion
Cancers, including pancreatic cancer, lymphoma, stomach cancer
Celiac disease—an autoimmune disease that causes damage to the lining of the intestines (intestinal villi)
Cystic fibrosis—a genetic condition that affects the pancreas and the transportation of pancreatic enzymes to the site of digestion
Damage to the intestines, such as from radiation treatment
Decreased intrinsic factor production
Diseases that affect circulation, such as congestive heart failure
Food intolerances and enzyme deficiencies
HIV and AIDS
Hyperthyroidism
Inflammatory bowel disease (Crohn disease and ulcerative colitis)
Liver diseases
Medications, such as phenytoin and those that inhibit stomach acid production
Pancreatic diseases and pancreatic insufficiency—can cause decreased amounts of pancreatic enzymes
Parasitic infections of the digestive tract, such as Giardia lamblia or a tapeworm
Scleroderma
Surgery, such as a bowel resection or gastric bypass
Zollinger-Ellison syndrome—a rare condition causing tumors in the pancreas and/or intestines
Signs and SymptomsThe signs and symptoms of malabsorption depend upon the underlying cause as well as the type and severity of nutrient deficiencies. They may become evident quickly or develop slowly and worsen over time. Some nutrients, such as vitamin B12, are stored by the body and symptoms only emerge when stores become depleted. Symptoms associated with insufficient pancreatic enzymes may not emerge until about 90% of the body's production capacity is disrupted.

Some of the most common signs and symptoms seen with general malabsorption include:

Persistent diarrhea
Fatty stools that are loose and foul-smelling (steatorrhea)
Failure to thrive (in children)
Abdominal pain, cramps, bloating, and gas
Other signs and symptoms may be due to general ill health or to specific deficiencies caused by malabsorption. They may include:

Weakness, fatigue
Fluid build-up in the abdomen (ascites)
Dry and scaly skin, rash
Inflammation of tongue (glossitis)
Muscle wasting, unexplained weight loss
Nausea and vomiting
Swelling of the hands, feet and legs (peripheral edema)
Inflammation of mouth (stomatitis)
Easy bruising, bleeding gums
Numbness and tingling in feet and hands
Paleness
Muscle or bone pain
The following are some complications that can develop over time as a result of chronic malabsorption:

Anemia
Delayed growth and development in children
Difficulty concentrating, confusion, and sometimes personality changes
Malnutrition
Osteoporosis
Deficiencies in vitamins such as vitamin A, vitamin D, vitamin K and trace minerals
TestingThe purpose of testing may be to:

Screen those at risk for malabsorption because of an underlying condition such as cystic fibrosis
Detect malabsorption, identify its underlying cause(s), and evaluate the types and severity of nutrient deficiencies present
Detect complications such as anemia
Monitor the effectiveness of treatment in people with malabsorption
There is no single test that can identify malabsorption or the underlying cause. Typically, a doctor will take into account many factors when ordering tests, including results from a physical examination, family history, medical history, and signs and symptoms. Testing will often be performed in steps with results leading toward a diagnosis while ruling out other possible causes. Testing typically involves ordering:

An initial set of general tests that evaluate body organs, cells, and digestion and that look for a cause for a person's persistent diarrhea, one of the most common symptoms of malabsorption
Specific follow-up tests that are used to detect or exclude diseases associated with malabsorption and to identify specific deficiencies and/or complications
Laboratory Tests

Initial testing may include:

Complete blood count (CBC) – to evaluate red blood cells to detect anemia and white blood cells to detect infections
Comprehensive metabolic panel (CMP) – to evaluate proteins, electrolytes, and organ function, including the liver
Prealbumin – this is used as a marker for protein malabsorption and indicates general nutritional status
Erythrocyte sedimentation rate (ESR) – to detect inflammation in the body which may be caused, for example, by inflammatory bowel syndrome
Fecal fat – to detect decreased ability to digest fat
Stool culture – to detect bacterial infection or bacterial overgrowth as cause of persistent diarrhea
Ova and parasite examination (O&P) – to detect parasites as cause of persistent diarrhea
Stool white blood cells – present in some inflammatory intestinal diseases
Thyroid stimulating hormone (TSH) – to detect or rule out thyroid disease
Based upon initial testing results, the person's symptoms, and the doctor's suspicions, follow-up testing may include one or more of the following:

Fecal occult blood test – to detect bleeding in the digestive tract
Levels of vitamin B12, vitamin D, vitamin A – to detect deficiency
Prothrombin time (PT) – to detect vitamin K deficiency
Celiac disease tests – to help diagnose this condition
Cystic fibrosis tests – to detect this disease
Fecal elastase, trypsin, trypsinogen, amylase, lipase – to evaluate pancreatic function
Tests sometimes ordered include:

Methylmalonic Acid (MMA) – to detect early vitamin B12 deficiency
Hydrogen breath test – to detect lactose intolerance and bacterial overgrowth in the digestive system (carbohydrate malabsorption)
D-Xylose – to evaluate carbohydrate digestion
Biopsy of the intestine
Non-Laboratory Tests

Testing to examine the digestive tract, liver, and/or pancreas is sometimes necessary and may include:

Abdominal ultrasound
CT scan
Endoscopy
Endoscopic retrograde pancreatography (ERCP)
Learn more about these imaging procedures at Radiologyinfo.org.

TreatmentA person affected by malabsorption can work with their doctor, a nutritionist, or other health care professionals to address and manage their condition. Treatment of malabsorption typically includes one or more of the following:

Addressing the underlying cause to the extent possible to minimize malabsorption symptoms and intestinal damage
Replacing missing nutrients; this may include the use of oral pancreatic enzyme supplements and the replacement of minerals and vitamins A, D, E, and K, vitamin B12 and folate, etc.
Making nutrient-rich foods available; for some people, a low-fat, high-protein diet may be recommended; for others, significant diet alterations, such as a gluten-free diet, may be necessary.
Working with the doctor to develop a treatment plan that is tailored to an individual person's clinical situation
Monitoring the person's health status over time; this often involves performing laboratory tests such as a CBC or CMP at regular intervals.
Related PagesOn This Site
Tests: CBC, CMP, Fecal Fat, Fecal Occult Blood, Vitamin B12 and Folate, Celiac Disease Tests, Xylose absorption test (coming soon), Stool Culture, O&P, Vitamin D, PT, Vitamin A, Sweat Choride, Trypsin, Trypsinogen
Conditions: Malnutrition, Celiac Disease, Vitamin B12 Deficiency, Cystic Fibrosis, Pancreatic Insufficiency, Vitamin K Deficiency

Elsewhere On The Web
American Gastroenterological Association: Patient Center
American Academy of Pediatrics, Healthy Children: Malabsorption
National Digestive Diseases Information Clearinghouse (NDDIC): Your Digestive System and How It Works
NDDIC: Celiac Disease
MedlinePlus Medical Encyclopedia: Malabsorption Syndromes

Article Sources

NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Dugdale, D. (Updated 2010 July 7). Malabsorption. MedlinePlus Medical Encyclopedia

(Updated 2011 May 19). Malabsorption. HealthyChildren

Dugdale, D. e. al. (Updated 2008 November 23). Pernicious anemia. MedlinePlus Medical Encyclopedia

David Zieve, D. and Hadjiliadis, D. (Updated 2011 May 1). Cystic fibrosis. MedlinePlus Medical Encyclopedia [On-line information].

Delgado, J. and Grenache, D. (Updated 2010 November). Malabsorption. ARUP Consult [On-line information].

Ruiz, A. (Revised 2008 January). Malabsorption. Merck Manual for Healthcare Professionals [On-line information].

Syed, S. Z. (Updated 2011 April 11). Bacterial Overgrowth Syndrome. Medscape Reference [On-line information].

Zieve, D. and Eltz, D. (Updated 2010 December 13). Cystic fibrosis - nutritional considerations. MedlinePlus Medical Encyclopedia [On-line information(2009 February). Short Bowel Syndrome. National Digestive Diseases Information Clearinghouse (NDDIC) [On-line information].

Guandalini, S. (Updated 2009 October 23). Pediatric Malabsorption Syndromes. Medscape Reference [On-line information].

Klapproth, J-M. (Updated 2009 December 28). Malabsorption. Medscape Reference [On-line information]. Mayo Clinic Staff (2010 January 19). Blind Loop Syndrome. MayoClinic.com [On-line information].

Dugdale, D. (Updated 2010 January 20). Tropical sprue. MedlinePlus Medical Encyclopedia [On-line information].

Dugdale, D. (Updated 2010 July 7). Lactose intolerance. MedlinePlus Medical Encyclopedia [On-line information].
(2009 August). Whipple's Disease. National Digestive Diseases Information Clearinghouse (NDDIC) [On-line information]. Available online at Accessed July 2011.

Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry, AACC Press, Washington, DC Pp 303-305.

Henry’s Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson R, Pincus M, eds. Philadelphia, PA: Saunders Elsevier: 2007, Pp 284-287, 291-292.

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. St. Louis: Elsevier Saunders; 2006, Pp 1878-1882.


This article was last reviewed on September 8, 2011. | This article was last modified on November 1, 2011.©2001 - 2011 by American Association for Clinical Chemistry •


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