The term malabsorption syndrome refers to a group of diseases characterized by insufficient absorption by the intestinal mucosa of nutrients from food, such as vitamins and minerals.
The malabsorption, in medical practice, indicates an "inadequate assimilation of food substances, caused by defects in digestion, absorption or transport of nutrients, which can cause the appearance of malabsorption syndrome.
Malabsorption can affect macronutrients (proteins, carbohydrates, fats), micronutrients (vitamins and minerals), or both, causing chronic diarrhea, weight loss, nutritional deficiencies, and gastrointestinal upset.
Furthermore, malabsorption can be global if it affects almost all nutrients or partial (isolated) if it is limited only to specific nutrients. The type and severity of the symptoms it causes depend on the type of problem underlying it and whether it affects one or more nutrients.
It is not considered malabsorption syndrome anorexia nervosa, despite the consequences of a long-term anorexia can cause such damage to the gastrointestinal tract as to generate a malabsorption syndrome.
Symptoms of the malabsorption syndrome they are various and are caused on the one hand by the increase in unabsorbed nutrients passing through the digestive tract and on the other by nutritional deficiencies resulting from insufficient absorption.
The most common symptoms include:
- chronic diarrhea (often steatorrhea, i.e. the presence of undigested fatty substances in the stool, which is responsible for their bad smell, clear, bulky and oily stools)
- slimming, with significant weight loss (or growth failure in children) despite adequate food consumption
In women, an interruption of the menstrual cycle may occur.
Symptoms can vary depending on the deficiencies and the nature of the unabsorbed nutrients. For example, a lack of protein can cause swelling and fluid build-up (edema) anywhere on the body, dry skin, and hair loss. Lack of vitamins and iron can be associated with osteoporosis or the presence of anemia, resulting in fatigue and tiredness.
Other associated disorders include:
- abdominal pain
- bloating and flatulence (air in the belly and its expulsion)
- brittleness of the nails
- increased tooth decay
- anal itching
- bad breath (halitosis)
- irregular heartbeat (arrhythmias)
- skin diseases (dermatitis)
- muscle cramps
- yellow coloring of skin and mucous membranes (jaundice)
- tremors and neurological disorders
The conditions and diseases that can cause the malabsorption syndrome there are many.
Malabsorption can be due to:
- diseases of the gastrointestinal tract, such as celiac disease, inflammatory bowel disease, enzymatic deficiency of the intestinal mucosa
- diseases that do not affect the intestine, such as diseases of the pancreas, liver or biliary tract, cancers of the digestive system
- post-operative complications, such as short bowel syndrome or damage caused by radiation therapies, bowel resection surgery or gastrointestinal bypass
- digestive tract infections, including viral, bacterial and parasitic infections such as tropical sprue, and Whipple's disease. However, these causes are less frequent
Other possible causes of malabsorption are:
- imbalances of the intestinal bacterial flora (dysbiosis), as in the case of intestinal bacterial overgrowth syndrome
- cystic fibrosis
- Lactose intolerance
- supplements or medications (e.g. laxatives)
- alcohol abuse
- acquired immunodeficiency syndrome and human immunodeficiency virus infection (AIDS and HIV respectively)
Malabsorption can be global or partial (isolated). Global malabsorption leads to a deficiency of almost all nutrients and results from diseases involving abnormalities of the mucous membrane of the small intestine or a decrease in the absorbent surface. partial malabsorption, or isolated, derives from diseases that interfere with the absorption of specific nutrients.
Symptoms of the malabsorption syndrome they are generally nonspecific (e.g. diarrhea) and can often be mistaken for other diseases. This makes it difficult to ascertain (diagnosis) and delays the start of treatment. In particular, malabsorption is less evident and often more difficult to recognize in the elderly than in children.
The doctor suspects the malabsorption syndrome in people with chronic diarrhea, weight loss, anemia or other signs of nutritional deficiencies, after seeing them and inquiring about their health history over time and that of family members (medical history).
If the cause of the disturbances is not immediately identifiable, he can prescribe, as initial tests, blood and stool tests. Blood tests may show specific deficiencies (lactose or vitamin B12), anemia, any changes in liver and pancreas enzymes, or the presence of abnormal antibodies. The examination of the faeces allows the identification of a possible microorganism responsible for a malabsorption of infectious origin.Furthermore, it allows to quantify both the quantity of fats present, thus identifying the steatorrhea (lipid malabsorption), and levels of chymotrypsin (key enzyme in the digestion of proteins, produced in the pancreas) to evaluate pancreatic function.
There is no single test that can ascertain (diagnose) one malabsorption syndrome and define the causes. Often, the different exams are performed in succession based on the results obtained in the previous ones. When the doctor confirms the presence of a malabsorption syndrome, can prescribe more specific investigations to identify the cause (etiology) or, if the person's state of health suggests a specific origin, can ask for further tests to verify if it is actually at the basis of the disorders and if there are particular deficiencies or complications. For example, if celiac disease is suspected, it is necessary to search for specific antibodies. The specialist may also prescribe gastro / colonoscopy to rule out inflammatory bowel disease and confirm celiac disease.
Laboratory tests that can help ascertain the causes of malabsorption are:
- biopsy, to highlight alterations in the structure of the mucosa of the small intestine
- imaging tests, for the analysis of the digestive system, liver and / or pancreas (endoscopy, abdominal ultrasound, computed tomography or x-rays with barium, cholangiopancreatography)
- pancreatic function test
- breath test (breath test), to evaluate lactose intolerance and a possible abnormal proliferation of some bacteria in the intestine
The care of the malabsorption syndrome it aims to act both on the condition / disease that causes malabsorption and on the consequent nutritional deficiencies, and on the symptoms associated with it.The treatment program must be personalized according to the person's nutritional and general health status, age, sex, concomitant diseases.
The general goals of therapy are:
- treatment of diarrhea and other ailments
- correction of nutritional deficiencies
- identification and treatment of the underlying disease
Treatment depends on the primary causes responsible for the malabsorption. In some cases, specific food supplements are required which, if the deficiencies are severe, are administered by the venous route.
If enzymatic deficiencies are present, a supplement of animal (pancreatin) or vegetable (bromelain and papain) digestive enzymes may be useful.
In the case of food intolerances or celiac disease, a very useful approach is to "exclude from the diet the foods to which the person is intolerant (for example, avoid foods that contain lactose or gluten).
The use of antibiotic therapies and probiotics can be useful for restoring the normal balance of the intestinal flora in malabsorption syndromes due to or associated with dysbiosis.
There malabsorption syndrome it often cannot be prevented, especially if the result of diseases such as celiac disease, cystic fibrosis or other chronic conditions. The person suffering from it should be closely followed by the doctor to manage the disease as best as possible.
After the verification of the syndromein fact, a path of nutritional treatment begins aimed at correctly reintegrating the missing substances in the body through the use of food supplements, vitamin supplements or the intake of enzymes, or at avoiding or replacing those nutrients that cause intolerance (for example example diets without gluten or lactose).
Long-term use of laxatives or antibiotics represents a risk factor for malabsorption, such as alcohol abuse.Therefore, these medicines should only be used when needed.
The complications of the malabsorption syndrome are directly associated with the type of nutrient (s) not absorbed. In cases where the causes of malabsorption are difficult to assess, malnutrition must first be avoided. Lack of vital nutrients can affect all systems in the body, including the heart, brain, muscles, blood, kidneys and skin.
If left untreated, the malabsorption syndrome it can lead to serious complications such as an increased chance of infections, bone fractures or slowed growth in children.
Clark R, Johnson R. Malabsorption Syndromes [Summary]. Nursing Clinics of North America. 2018; 53, 361-374