Anorexia Nervosa (AN) is a serious psychiatric disorder that carries significant medical risks due to undernutrition. This condition affects every organ system, including the gastrointestinal (GI) tract, which is vulnerable to nutrient restriction. Blood in the stool is a serious medical symptom that can arise from the physical strain and systemic damage caused by AN. This symptom always warrants professional medical evaluation to determine the underlying cause and severity.
Anorexia and Mechanical Causes of Lower GI Bleeding
Mechanical trauma in the lower GI tract, specifically the anus and rectum, is the most frequent cause of visible blood in the stool for individuals with AN. Chronic malnutrition and dehydration often lead to significant constipation. Low caloric intake reduces the bulk of waste material, and inadequate fluid intake makes the stool hard and difficult to pass.
Passing hardened stool necessitates excessive straining during a bowel movement. The physical force of straining can cause small tears in the delicate lining of the anal canal, known as anal fissures. Bleeding from a fissure is typically bright red, appearing either on the toilet paper, coating the outside of the stool, or dripping into the toilet bowl.
Straining also puts pressure on the veins in the rectum and anus, leading to the development or worsening of hemorrhoids, which are swollen blood vessels. Hemorrhoids are another common source of bright red, superficial bleeding. Laxative misuse, sometimes seen in AN, can also disrupt normal bowel function and may contribute to the appearance of blood or mucus in the stool.
Systemic Effects of Starvation on the GI Tract
Beyond mechanical trauma, the state of starvation inherent to AN creates a fragile environment within the entire gastrointestinal lining, increasing the risk of internal bleeding. Chronic undernutrition deprives the cells lining the intestines of the necessary energy and nutrients to maintain their structure, leading to mucosal atrophy. This atrophy causes the intestinal wall to thin and the villi to flatten, making the tissue highly susceptible to injury.
The body’s inability to repair damaged tissue is compromised by deficiencies in protein and essential vitamins, which are necessary for cellular regeneration and blood clotting. A weakened, atrophied lining is more easily eroded, potentially leading to ulcer formation anywhere along the GI tract, which can cause significant bleeding. The lack of food substrate in the intestines creates “luminal starvation,” which impairs the gut’s protective barrier functions.
This systemic damage is compounded by motility issues like gastroparesis, or delayed gastric emptying, where food moves slowly through the digestive system. When the transit time of waste is slowed, retained matter can linger and irritate the weakened intestinal lining, making internal injury more likely. The combination of a fragile mucosal barrier and impaired healing capacity means that internal bleeding may be prolonged or harder to stop in a malnourished state.
Recognizing Serious Bleeding and Seeking Immediate Care
Any instance of blood in the stool for a person with AN warrants immediate medical evaluation because their compromised health status makes them vulnerable to complications. Identifying the color of the blood is a helpful first step in determining the likely source. The passage of bright red blood, known as hematochezia, usually suggests bleeding from the lower GI tract, such as the rectum or colon, and is often due to mechanical causes like fissures or hemorrhoids.
Melena is characterized by black, tarry, and often foul-smelling stools. Melena indicates that the blood has been chemically altered by digestive enzymes and stomach acids, suggesting a bleeding source higher up in the GI tract, such as the stomach or small intestine. This can be a sign of a more serious issue like a bleeding ulcer.
Regardless of the color, certain associated symptoms signal a medical emergency. Warning signs include dizziness, lightheadedness, or fainting, which may indicate significant blood loss leading to hypovolemia. Other serious symptoms are severe abdominal pain, a rapid heart rate, or confusion. A patient with AN experiencing any GI bleeding needs a definitive diagnosis because their overall physical fragility elevates the risk of severe complications from even moderate blood loss.