What causes Anaemia?

Anaemia can be caused by increased blood loss from the body or decreased production of red blood cells or an accelerated breakdown of red blood cells in the body. In this article, we will concentrate on Blood Loss from the gastrointestinal tract, which is the commonest cause of Anaemia.

Anaemia as a result of Blood Loss often produces a picture termed as Iron-Deficiency anaemia. The body’s iron stores will be low and the red blood cells appear smaller and pale under the microscope.

The following are the common gastrointestinal sites of blood loss:

Stomach

The stomach is one of the commonest sources of blood loss in an anaemic patient.

A gastric (stomach) or duodenal ulcer is a very common condition. Collectively, these two conditions are known as Peptic Ulcer Disease. Chronic blood loss over a period of time can occur from the edges and base of the ulcer and can result in a gradual drop in haemoglobin over time. If left undiagnosed, the ulcer can have a sudden and catastrophic bleed which is life-threatening.

The risk factors for the development of Peptic Ulcer Disease include Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), Steroid drugs, Helicobacter.pylori, smoking and alcohol ingestion. The presence of blood-thinners or anti-platelet drugs, in turn, increases the risk of a catastrophic bleed due to the decreased blood clotting ability.

Another cause of gastric bleeding is that of a gastric tumour. Gastric tumours usually cause slow gradual bleeding rather than an acute bleed. There are a few groups of gastric tumour, and these include an adenocarcinoma, leiomyoma and a GIST.

Less common causes of gastric bleeding include a Dieulafoy lesion (single aberrant artery just underneath the stomach lining) or angiodysplasia (torturous and tangled mass of aberrant veins)

Bleeding from the stomach usually manifests as black tarry stools. The black colour is derived from the digestion of blood as it passes through the gastrointestinal tract. In acute catastrophic bleeding, the patient can pass out frank blood in the stools.

Colon and Rectum

 

The colon (large intestine) is another common source of blood loss from the gastrointestinal tract.

 

Colonic diverticular bleeding is a common cause of colonic bleeding. Diverticuli are thin-walled outpouchings of the colon with a vessel draped over the base of the diverticuli. Diverticular bleeding can present as massive bleeding with multiple episodes of passage of blood and blood clots. Diverticular bleeding tends to be acute rather than chronic bleeding.

A colon or rectal tumour is a cause of chronic and gradual colon bleeding that may only be noticeable when the patient has symptoms of anaemia (when the haemoglobin has dropped sufficiently) or if an incidental blood test is done.  There may be accompanying symptoms of change in bowel habits, blood in stools, abdominal pain or loss of weight.

 

Bleeding from piles (haemorrhoids) is a fairly common occurrence and can be daunting to the individual who sees the toilet bowl splashed with blood. Contrary to popular belief, the amount of blood lost from a bleeding pile is minimal and anaemia is not common. Anaemia tends to occur in individuals with large piles that bleed daily over prolonged periods of time. Most bleeding from piles tends to stop spontaneously after a few days.

 

Individuals who have undergone radiotherapy treatment to the pelvis, usually in the context of cancers of the Uterus/Cervix or Prostate can develop a condition termed Radiation Proctitis. Small torturous vessels termed Telangiectasia can develop in the rectum as a side effect of radiation. These telangiectasia are very friable and are prone to spontaneous rupture and bleeding and can produce fairly profound anaemia. The treatment will be to apply an Argon Plasma Coagulation probe to the telangiectasia.

 

Less common causes of colonic bleeding include Angiodysplasia (similar to what is described above in the Stomach) and Ulcerative Colitis.  Angiodysplasia can occur in the colon, particularly in the right-sided colon. Angiodysplasia is also more common in individuals with chronic kidney failure. Bleeding from angiodysplasia is intermittent and can be of small amounts which in turn makes detection difficult. Ulcerative Colitis is an autoimmune condition whereby the colon becomes inflamed and friable and develops multiple ulcerations, all of which contribute to colonic bleeding.

 

Small intestine 

 

The small intestine is a much less common cause of blood loss from the gastrointestinal tract as compared to the Stomach or Colon. Small intestinal blood loss tends to be a small amount in nature and hence often undetectable. Anaemia may be the only visible sign and the small intestine is usually suspected only when the stomach and colon have been excluded as possible bleeding sources.

 

A Meckel’s diverticulum is a possible source of small intestinal bleeding which is often occult in nature and also undetectable. A Meckel’s diverticulum is a large aberrant outpouching from the small intestine that usually occurs within 60cm (2ft) of the small intestine-colon junction. The lining of the Meckel’s diverticulum can take on similar characteristics as that of the lining of the stomach and is hence susceptible to forming ulcers.

 

Other causes of small intestinal blood loss include Ulcers, Crohn’s disease and Angiodysplasia.  Ulceration can occur in the small intestine, though this occurs much less common compared to the stomach. Crohn’s disease is an autoimmune condition that affects the entire gastrointestinal tract and causes inflammation of the lining that makes it friable and susceptible to bleeding. Angiodysplasia can occur in the small intestine, similar to the stomach and colon and is also more common in individuals with chronic kidney failure.