What is malabsorption syndrome and its causes?

What is malabsorption syndrome?

Malabsorption syndrome is the symptoms and signs of nutritional deficit secondary to inadequate intestinal absorption of nutrients (proteins, fats, carbohydrates, vitamins or minerals).

Malabsorption syndrome can be the result of a defect in the gastrointestinal tract that leads to nutritional deficiency or malnutrition.

What is the cause that causes it?

It is a comprehensive syndrome with a complex pathophysiology and may be due to a multitude of causes depending on the origin of the problem and the type of malabsorption (it may be a total or specific deficit of a particular nutrient: carbohydrates, fats, iron, protein)

Nutrient assimilation can be divided into two processes: digestion and absorption.

Digestion consists of the fragmentation of food by gastric and pancreatic juices and bile salts, which the body will later assimilate through absorption.

Absorption is the transport of nutrients from the intestinal walls to the blood.

In the nutrient assimilation phase (absorption), three processes are distinguished:

  • Intestinal lumen phase: where food hydrolysis takes place
  • Mucous degree: in which nutrients are absorbed in the intestinal mucosa
  • Transport phase: once the nutrients are interested, they are transported through the bloodstream

What types exist?

There are different types of malabsorption depending on the affected nutrient:

fat malabsorption

    • Altered secretion of bile and pancreatic salt levels
    • Bile salt deficiency
    • Structural abnormalities of the intestinal wall that prevent absorption

Malabsorption of carbohydrates ( lactose intolerance is the most common)

  • Congenital or acquired lactase deficiency

Vitamins and trace elements

  • Vitamin B12 deficiency is the most frequent and may be due to intrinsic factor deficiency, pancreatic insufficiency, bacterial overgrowth and secondary intestinal resections.

There are, in turn, numerous diseases or conditions that cause difficulties in intestinal absorption. They can be classified into:

Causes of exocrine pancreatic insufficiency

  • Chronic pancreatitis
  • Cystic fibrosis
  • Pancreatic cancer
  • pancreas resection

Bile salt deficiency

  • Cholestatic liver disease
  • bacterial overgrowth
  • biliary obstruction

Diseases of the mucosa and intestinal wall

  • Celiac Disease
  • Crohn’s disease
  • tropical sprue
  • short bowel syndrome
  • radiation enteritis
  • Whipple’s disease
  • IgA immunodeficiency
  • amyloidosis
  • AIDS enteropathy
  • Lactase deficiency
  • mastocytosis
  • eosinophilic enteritis
  • Giardiasis

Vascular and lymphatic causes

    • Intestinal lymphangitis
    • congestive heart failure
  • Chronic mesenteric insufficiency
  • intestinal lymphoma

Other causes

  • Post gastric or intestinal surgery
  • Intestinal lymphagiectasis
  • atrophic gastritis

What are the symptoms of malabsorption syndrome?

There are digestive and extraintestinal symptoms derived from nutritional deficiency.

digestive symptoms

  • Acute, intermittent, or chronic diarrhoea
  • Foul-smelling, pasty, pale, bulky stools
  • Weightloss


  • Microcytic anaemia (iron deficiency)
  • Macrocytic anaemia (vitamin B12 deficiency)
  • Bleeding (vitamin K deficiency)

skin and mucous membranes

  • Bruising, petechiae (vitamin K and vitamin C deficiency)
  • Oedema (protein and albumin deficiency )
  • Alterations in the nail (iron deficiency)


  • Menstrual disturbances, impotence and infertility (protein deficiency)

Nervous system

  • Peripheral neuropathy (vitamin B12 and thiamine deficiency)
  • Vision disturbances (vitamin A deficiency)

Symptoms of protein malabsorption

  • Weight loss and muscle mass
  • albumin deficiency
  • Oedema, ascites and heart failure (advanced phases)

Symptoms of carbohydrate malabsorption

  • Osmotic (watery) diarrhoea
  • Flatulence
  • “Explosive” diarrhoea due to the mixture of bloating and watery diarrhoea

How can it be detected?

Depending on the elements (fats, carbohydrates, proteins) of which a disorder or deficit is suspected, the following diagnostic tests are usually carried out:

Recommended diagnostic examinations in fat malabsorption:

  • Qualitative test by Sudan stain: it is considered positive if the percentage of fat eliminated is greater than 15% compared to that ingested.
  • Quantitative test (Van de Kramer): consists of collecting faeces for 72 hours, a period in which the patient must carry out a fat overload of 100 g per day. It is considered positive (steatorrhea) if faecal excretion exceeds 6 g per day.
  • Infrared reflection analysis or NIRA test
  • Triolein breath test

Diagnostic examinations in carbohydrate malabsorption (fundamentally rule out lactose intolerance )

  • D-Xylose test
  • Lactose/hydrogen breath test

Diagnostic explorations in protein malabsorption:

  • The most widely used technique is the determination of alpha one antitrypsin by radioimmunoassay

The study of malabsorption syndrome is usually complemented with imaging tests:

  • Abdominal ultrasound, computed tomography (CAT), magnetic resonance imaging, endoscopic cholangiopancreatography, and cholangiopancreatography-MRI.
  • Gastrointestinal barium study
  • Gastroscopy and colonoscopy with intestinal biopsy
  • capsule endoscopy

What is the recommended treatment?

Malabsorption syndrome can be divided into four groups depending on the treatment response.

  • Complete control of absorption: when the causal process is not curable, it is possible to control intestinal absorption ( celiac disease, intolerance to carbohydrates, bacterial overgrowth)
  • Control of the causal process: when we cannot cure the causal process, but we can control it (inflammatory bowel disease, Crohn’s disease, intestinal lymphoma)
  • Support treatment: when we cannot cure or control the causal process (intestinal infarction, short bowel syndrome, small bowel cancer)

The rest of the treatment will be based on enteral nutrition through oral supplements depending on the nutritional deficit (iron, vitamin B12, protein), specific dietary and nutritional recommendations ( celiac disease, lactose intolerance) and intravenous or parenteral nutrition in more severe cases, of advanced malnutrition.

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