Pathophysiology and Metabolism

Crohn’s disease is believed to manifest from environmental triggers and genetic predispositions. In combination, these factors cause an abnormal immune response within the digestive tract. This response triggers the immune system to release cytokines- cells that signal other cells to move towards inflamed sites within the body. The cytokines released in Crohn’s disease then cause the inflammatory pathway to overreact. This overreaction can damage the intestinal mucosa lining of the small and large intestines.

Crohn’s disease may present itself in varying parts of the GI tract. Crohn’s may manifest in a skipping pattern, observed as discontinuous sections of inflammation and injury. The most commonly affected area in Crohn’s disease is the ileum of the small intestine and colon. The intestines are lined with a series of mucosal layers. These layers play many roles. One crucial responsibility of the mucosal layer is to absorb nutrients from food into the bloodstream. All layers of the gastrointestinal mucosa may experience damage. This damage may result in the creation of fistulas. A fistula is an abnormal passage between organs or from an organ to an external surface. When the fistula heals, it leaves behind fibrotic tissue which can then contribute to reoccurring strictures (narrowing) and bowel obstructions. These conditions often require surgical intervention to correct. Over the course of their lives, Crohn’s disease patients may experience phases of worsening or improving symptoms.

Malabsorption of nutrients throughout infected areas of the GI tract is common in Crohn’s disease. The determination of which nutrients being inadequately absorbed depends on the site of infection. Vitamins and minerals are absorbed in various parts of the GI tract. Therefore, some vitamins may be unaffected while others are not absorbed. Malabsorption occurs once the mucosal lining experiences damage from the overreacting immune response. The cells are then altered and can no longer effectively absorb nutrients. As a result, patients commonly present with multiple vitamin/mineral insufficiencies and deficiencies. These insufficiencies and deficiencies may lead to other serious health conditions and can be managed with vitamin/mineral supplements.

Similarly, malabsorption of nutrients may lead to protein-energy malnutrition. This can result from inadequate oral intake. Patients may avoid eating certain or all foods out of fear of experiencing abdominal pain often associated with eating. Malnutrition may also result because the body’s energy needs increase in response to the active and chronic inflammation. During this time, the immune system is working on overdrive and burning more energy. This puts the body in a hypermetabolic state and energy demands increase. However, these needs are often not met by the diet since patients may restrict food choices in an attempt to manage symptoms.

Interpretation of Tests and Surgical Procedures

Crohn’s disease is diagnosed using the analysis of various symptoms, endoscopic results and biopsy findings. Common symptoms associated with Crohn’s disease include severe abdominal pain, diarrhea and tenesmus. Crohn’s disease patients are likely to experience more abdominal cramping but less bloody stools than UC patients. Weight loss is also common among Crohn’s disease patients due to the inability to effectively digest and absorb nutrients from food. Food consumption is frequently decreased to avoid abdominal pain and related symptoms. Crohn’s disease patients may only experience mild symptoms, or symptoms resultant of chronic inflammation, such as dermatitis. These symptoms may help guide health care providers to accurately diagnose Crohn’s disease.

Endoscopic and biopsy findings are collected during an endoscopy and colonoscopy. Both procedures involve the insertion of a long, flexible tube with a camera and light into the digestive tract while the patient is sedated. This tube allows the health care provider to assess the state of the GI tract and detect any abnormalities or changes. A colonoscopy enters through the anus and assessed the large intestine, and the endoscopy enters through the oral cavity and assesses the upper GI tract from the mouth to the small intestines. Some telltale signs of Crohn’s disease observed during these procedures include a cobblestone appearance on the mucosa. This cobblestone appearance may occur due to recurrent ulcers, fissures and other damage to the GI tract. During the endoscopy and/or colonoscopy, small samples of the tissue are collected to be analyzed for the presence of infections, anti-saccharomyces cerevisiae antibodies (ASCA), cancer, or any other biomarkers for further diagnoses. ASCA is an antibody commonly present in Crohn’s disease patients and helps to distinguish between Crohn’s and UC.

Abdominal Computed Tomography (CT) scans are another tool used to diagnose Crohn’s disease. A CT scan takes a cross-sectional x-ray of a patient’s abdomen and reveals any abnormalities, such as fissures, fistulas, ulcers, or strictures. These findings may indicate the need for surgical interventions. To correct strictures (narrowing of the GI tract) up to six inches in length, a strictureplasty is performed to open the pathway. Bowel resections are necessary when disease portions of the GI tract that are too large to be treated must be removed completely. Once the infected portion is removed, the remaining ends are reattached via an anastomosis. A colectomy is similar to bowel resections except it removes diseased portions in the colon, or the entire colon. Finally, a proctocolectomy may be necessary if both the colon and rectum are infected and need to be removed. The small intestines may be reattached directly to the anus via an ileoanal anastomosis. If the small intestines cannot be reattached to the anus, it may need to be redirected to a surgically created hole in the abdomen where waste exits into a bag, called an ileostomy.

Currently there is no treatment for Crohn’s disease. Medications aimed to suppress the immune system and inflammatory response may be used to help manage the progression of the disease. Diet and bowel rest may also be implemented to manage symptoms. As there is no cure at this time, surgical procedures are utilized to continually monitor and manage the disease state.

Pertinent Laboratory Data

Laboratory data is collected to further assess patient’s nutritional status and identify any biomarkers for disease states or areas needing supplementation. Lab Value Normal Range Abnormalities:

• Vitamin A — 15-60 microgram (mcg) /deciliter (dL)
• Vitamin E — 5.5-17 mcg/milliliter (mL)
• Vitamin K — 0.2-3.2 nanogram (ng) / mL
• Vitamin D — (25-OH Vitamin D) 21 ng /mL 25-80 ng/mL Low
• Vitamin B6 16.9 nanomoles (nmol)/ liter (L) 20-125 nmol/L Low
• Vitamin B12 249 picograms (pg)/mL 213-813 pg/mL
• Folate — 2-20 ng/mL
• Total Iron-Binding Capacity (TIBC) 310 mcg/mL 250-450 mcg/mL
• Zinc 75 mcg/dL 60-120 g/dL

Fat-soluble vitamins include Vitamins A, D, E and K. In contrast to water-soluble vitamins, fat-soluble vitamins are stored in the body after being absorbed. The stores can then later be accessed and released when levels are low. Crohn’s relate damage to the GI tract may impact the efficacy of bile – an enzyme stored and released from the pancreas to help digest fatty foods. Therefore, patients with Crohn’s disease may not be able to effectively digest fat and likely experience malabsorption of fat-soluble vitamins. It is then important to monitor fat-soluble vitamins for insufficient levels. Inadequate levels may indicate malabsorption and the need for supplementation.

Of the four fat-soluble vitamins, only vitamin D levels were tested. BR’s vitamin D level is low at 21 ng/mL. This may be an indicator of inadequate oral intake of Vitamin D containing foods (animal sources: fatty fish, eggs, dairy, meat, poultry) or inadequate sunlight exposure. In relation to BR’s Crohn’s Disease diagnosis, it is likely a sign of Vitamin D malabsorption within the GI tract. BR is currently on a daily Vitamin D3 supplement to replenish these levels. Vitamin D3 is a further broken down and more readily absorbed form of Vitamin D. Vitamin D3 is also shown to be more effective in raising serum vitamin D levels when given in high doses than Vitamin D2 (less broken-down form of vitamin D), which is why vitamin D3 was selected for BR.

Vitamin B6 is a water-soluble vitamin found naturally in foods and absorbed in the second part of the GI tract, the jejunum. Individuals with autoimmune diseases, such as Crohn’s Disease, are at risk of Vitamin B6 insufficiency/deficiency; the reasoning for this is unknown but suspected it may be due to the chronic inflammation throughout the GI tract. BR’s Vitamin B6 level was slightly below the desired range at 16.9nmol/L. This may be an indication of malabsorption related to Crohn’s Disease associated GI damage, or due to the removal of parts of BR’s ileum during his two documented ileocolic resections. Individuals with mild vitamin B6 deficiency may not present with any signs or symptoms until it becomes a chronic deficiency. A chewable multivitamin was recommended to BR to restore levels to be within normal limits (WNL).

Patients with a history of ileal resections commonly present with Vitamin B12 deficiency because Vitamin B12 is absorbed in the last part of the small intestines called the ileum. BR underwent two ileocolic resections, which involves the removal of part or the entirety of the ileum. This then impacts the functionality and ability to absorb Vitamin B12 and other vitamins and minerals. However, BR’s Vitamin B12 level was WNL, indicating he is effectively receiving and absorbing Vitamin B12. BR is currently taking a monthly Vitamin B12 supplemental injection to maintain these levels. The injection allows BR to bypass the digestive tract and directly absorb Vitamin B12 into his blood stream and tissues. This practice effectively restores and maintains Vitamin B12 levels in individuals with altered GI function.

Folate levels are often evaluated in Crohn’s Disease patients to monitor for folate deficiency. Folate is absorbed in all parts of the small intestines, and consequently may not be absorbed in Crohn’s Disease patients. Additionally, the use of certain medications (none of which BR is on) and decreased intake of dark, leafy green vegetables may contribute to folate deficiency. Crohn’s patients may regularly avoid dark, leafy green vegetables because of the fiber content which may cause GI upset. BR’s folate levels were not tested and therefore could not be assessed.

Total iron binding capacity (TIBC) is also reviewed to further assess the nutritional health of patients. TIBC reflects the ability of the blood to bind with iron. A low level of TIBC may indicate iron deficiency related anemia. Anemia is a common condition among Crohn’s Disease patients due to chronic malabsorption throughout the GI tract. The most common cause of anemia in IBD patients is iron deficiency. BR’s TIBC levels were WNL. Iron supplementation and anemia are not current concerns.

Lastly, zinc deficiency may occur in patients with high-output fistulas or those experiencing recurrent diarrhea. Zinc deficiency may manifest resultant from high fluid losses associated with these conditions. BR’s zinc level was WNL; therefore, supplementation was not necessary. All discussed laboratory values were used to assess BR’s nutritional status and further develop an individualized plan of care.