Written and peer-reviewed by physicians—but use at your own risk. Read our disclaimer.

banner image

amboss

Trusted medical answers—in seconds.

Get access to 1,000+ medical articles with instant search
and clinical tools.

Try free for 5 days

Malabsorption

Last updated: April 9, 2021

Summarytoggle arrow icon

Despite the distinct underlying pathological mechanisms of malabsorption and maldigestion, the term malabsorption is used to refer to both disorders in clinical practice. Malabsorption (e.g., celiac disease, lactose intolerance) describes a malfunction of the intestinal wall, resulting in the insufficient absorption of breakdown products. Maldigestion (e.g., exocrine pancreas insufficiency or cholestasis) is caused by an intraluminal disorder (insufficient secretion of pancreatic enzymes or bile), which prevents the adequate breakdown of food in the intestinal lumen. Both disorders can lead to malnourishment, which, in children, may manifest with delayed and inadequate physical development. Adults mainly present with chronic diarrhea, weight loss, and signs of malnutrition (e.g., iron deficiency anemia). Diagnostic tests assess the digestion of individual food components. Management focuses on the underlying disease; e.g., patients with celiac disease should adhere to a gluten-free diet.

Malabsorption disorders can be caused by either the insufficient absorption or digestion of nutrients. The condition can be further defined as global or partial.

  • Global malabsorption: in diseases causing diffuse mucosal damage or a reduction of the absorptive surface (e.g., celiac disease)
  • Partial malabsorption: caused by a localized absorption impairment, resulting in deficiencies of specific nutrients (e.g., vitamin B12 deficiency in patients with diseases affecting the terminal ileum)

Maldigestion

Maldigestion is an impaired breakdown of food in the intestinal lumen.

Exocrine pancreatic insufficiency

Other causes

  • Gastric resection: lack of gastric acid → impaired breakdown of nutrients
  • Bile acid deficiency: : e.g., cholestasis, bile acid malabsorption → incomplete emulsification of fats
  • Medications: orlistat
    • Mechanism of action: Reversibly inhibits gastric and pancreatic lipase, resulting in a decrease in fat breakdown and absorption
    • Indication: weight loss in obese patients
    • Recommendation: should be taken with meals containing fat
    • Side effects: numerous gastrointestinal side effects

Malabsorption

Malabsorption is an impaired absorption of digested food caused by alterations of the intestinal mucosa.

General symptoms

Deficiencies

  • Blood tests: macrocytic and/or microcytic anemia; ↓ electrolytes, ↓ total protein, vitamin deficiencies
  • Stool tests
    • Analysis of fecal fat; over 72 hours (e.g., using Sudan stain)
    • Detection of pathogens
  • D-xylose absorption test: assesses the absorptive function of the upper small intestine
    • Physiology
      • The intestinal absorption of D-xylose requires intact mucosa but no digestive enzymes.
      • Most of the absorbed D-xylose is eliminated by the kidneys without being metabolized, which is why insufficient intestinal absorption results in low urine xylose levels.
    • Method: The patient fasts overnight, then 25 g of D-xylose is administered orally. Then:
      • Urine is collected over 5 hours. Urine D-xylose levels < 4 g/5 h are considered pathological.
      • A venous blood sample is collected after one hour. Serum D-xylose levels < 20 mg/dL are considered pathological.
    • Interpretation
  • Hydrogen breath test: assess the intestinal absorption of individual carbohydrates
  • Further testing (for underlying diseases): e.g., celiac disease or lactose intolerance

Protein-losing enteropathy

  • Etiology
  • Clinical features: hypoalbuminemia with peripheral edema
    • In cases of systemic diseases, symptoms may be those of the underlying condition.
    • Further gastrointestinal symptoms may occur depending on the underlying disorder.
  • Treatment: treatment of the underlying disease

The differential diagnoses listed here are not exhaustive.

  • Symptomatic treatment
    • Oral supplementation of fluid, nutrients, and vitamins
    • Calorie and protein-enriched diet
    • IV nutrition in severe cases (e.g., following extensive intestinal resection)
  • Causal treatment of the underlying disease
  1. Buchman AL. The Medical and Surgical Management of Short Bowel Syndrome. MedGenMed. 2004; 6 (2).
  2. Pazirandeh S, Burns DL. Overview of vitamin A. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/overview-of-vitamin-a#H10.Last updated: October 26, 2016. Accessed: December 14, 2016.
  3. Ansstas G. Vitamin A Deficiency. In: Griffing GT, Vitamin A Deficiency. New York, NY: WebMD. http://emedicine.medscape.com/article/126004-clinical#b5. Updated: October 12, 2016. Accessed: December 14, 2016.
  4. Drezner MK. Patient education: Vitamin D deficiency (Beyond the Basics). In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/vitamin-d-deficiency-beyond-the-basics#H9.Last updated: June 9, 2015. Accessed: December 14, 2016.
  5. Pazirandeh S, Burns DL. Overview of vitamin D. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/overview-of-vitamin-d?source=see_link#H9.Last updated: January 15, 2016. Accessed: December 14, 2016.
  6. Pazirandeh S, Burns DL. Overview of vitamin E. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/overview-of-vitamin-e#H7.Last updated: October 3, 2016. Accessed: December 12, 2016.
  7. Pazirandeh S, Burns DL, Lipman TO, Motil KJ, Hoppin AG. Overview of Vitamin K. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/overview-of-vitamin-k.Last updated: April 13, 2016. Accessed: December 14, 2016.
  8. Nguyen-Khoa D-T. Beriberi (Thiamine Deficiency). In: Khardori R, Beriberi (Thiamine Deficiency). New York, NY: WebMD. http://emedicine.medscape.com/article/116930-overview#showall. Updated: July 1, 2016. Accessed: December 15, 2016.
  9. Xiong GL. Wernicke-Korsakoff Syndrome. In: Bienenfeld D, Wernicke-Korsakoff Syndrome. New York, NY: WebMD. http://emedicine.medscape.com/article/288379-overview#showall. Updated: April 18, 2016. Accessed: December 12, 2016.
  10. Gill RS. Riboflavin Deficiency. In: Griffing GT, Riboflavin Deficiency. New York, NY: WebMD. http://emedicine.medscape.com/article/125193-overview. Updated: August 9, 2016. Accessed: December 16, 2016.
  11. Pazirandeh S, Burns DL. Overview of water-soluble vitamins. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/overview-of-water-soluble-vitamins?source=search_result&search=niacin%20deficiency&selectedTitle=1~32.Last updated: November 9, 2016. Accessed: December 16, 2016.
  12. Vitamin B5 (Pantothenic acid). http://umm.edu/health/medical/altmed/supplement/vitamin-b5-pantothenic-acid. Updated: July 16, 2013. Accessed: December 15, 2016.
  13. Frye RE. Pyridoxine Deficiency. In: Griffing GT, Pyridoxine Deficiency. New York, NY: WebMD. http://emedicine.medscape.com/article/124947-overview#a4. Updated: September 15, 2016. Accessed: December 15, 2016.
  14. Schick P. Megaloblastic Anemia. In: Besa EC, Megaloblastic Anemia. New York, NY: WebMD. http://emedicine.medscape.com/article/204066-overview#a1. Updated: October 29, 2016. Accessed: December 15, 2016.
  15. Schrier SL. Clinical Manifestations and Diagnosis of Vitamin B12 and Folate Deficiency. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-vitamin-b12-and-folate-deficiency.Last updated: July 15, 2016. Accessed: December 15, 2016.