Diagnostic tests for specific conditions are described in the following chapters, but it is important for anyone suffering from GI symptoms that they feel are caused by or related to gluten to understand the basic tests used to facilitate a diagnosis. What you see and feel may be the tip of a hidden iceberg, and a gluten-free diet may not help you avoid the impact of a collision.
Rule Out Celiac Disease
If you are suffering from symptoms that include:
chronic diarrhea or constipation
gas/bloating
anemia
vomiting
canker sores
weight loss
failure to thrive (in children)
vitamin deficiencies
lactose intolerance
behavioral issues
brain fog
neuropathies
and/or celiac disease has been diagnosed in a family member, you should be tested for celiac disease before starting a gluten-free diet. Once you are on the diet, testing becomes more difficult to interpret, can be inaccurate, and may require a gluten challenge that brings a return of unwanted symptoms.
The blood and endoscopic tests for celiac disease are detailed in chapter 17. These are the definitive tests to determine if someone is mounting an autoimmune reaction to gluten that is destroying the lining of their small intestine and interfering with digestion.
Get Basic Standard of Care Tests
If you have continuing GI symptoms, it is important to know if your gut/body is inflamed, if you are anemic, and to measure specific vitamins and minerals to assess for the presence and severity of malabsorption. These tests also help your doctor to determine what part(s) of the intestine are involved and the degree of damage.
Tests include:
Erythrocyte sedimentation rate and C-reactive protein—reveals the degree of inflammation in the body; they are not specific for any particular condition or organ.
Ferritin—a parameter of iron stores, inflammation, or deficiency due to malabsorption or chronic blood loss. High values reflect excessive iron stores, as in hemochromatosis, a genetic disorder of excessive iron absorption that is associated with celiac disease.
Folic acid—a parameter of disease of the upper small intestine, where it is absorbed. A deficiency or low levels are common in celiac disease and rare in Crohn’s disease, which is predominantly in the ileum or lower small intestine.
B12—a parameter of lower small intestinal disease or stomach issues such as bacterial overgrowth or chronic gastritis.
Vitamin D—necessary for calcium absorption (in turn, necessary for bone formation and muscle contraction). Vitamin D is formed in the skin from sun exposure that can be impeded by sunblock and lack of outdoor activity. Dietary deficiency is also common.
Parathyroid hormone—the parathyroid monitors and manages calcium metabolism. With calcium deficiency, the hormone increases to retain calcium and maintain blood levels to ensure cardiac, blood, and muscle function.
Stool testing—important in GI issues to look for blood and, with diarrhea, to look for infections.
If there are neurological issues, vitamins E, B1, B2, and B6 as well as copper levels should be measured. If there are skin rashes or taste issues, zinc should be measured.
Use Breath Tests to Further Narrow the Diagnosis
Breath tests are used to diagnose a number of conditions that produce GI symptoms, including fructose and lactose intolerance, bacterial overgrowth, and intestinal transit time. It is important to exclude these conditions in patients with irritable bowel syndrome (IBS) and celiac disease with persistent symptoms.
The sugars and carbohydrates we eat are normally digested and absorbed in the small intestine. But when they are mal-absorbed, they get into the colon, where they are fermented by the bacteria that live there. The bacteria dine happily on them, producing gas, water, and the painful symptoms known to those suffering from IBS. This also produces the hydrogen and/or methane gas that are a normal by-product of carbohydrate digestion. These gases are absorbed into the bloodstream and eliminated through the lungs in the breath.
Patients drink different sugars (sucrose, glucose, lactulose, fructose), and their breath is measured every half hour with special analyzers in order to measure the “peaks” of hydrogen and to determine if and how rapidly you are absorbing or mal-absorbing sugars. If lactose and fructose are digested and absorbed in the small intestine, you normally will not produce excess hydrogen.
Therefore, an increase in hydrogen indicates specific intestinal problems. With rapid transit, hydrogen is produced soon after the sugar is ingested; with bacterial overgrowth, hydrogen levels peak twice—once when digested by bacteria not normally found in the small intestine and later by the bacteria in the colon.
Breath tests are a simple and safe method of measuring alterations in digestion that create symptoms, but they have limitations. Some people have colon bacteria that produce methane gas instead of hydrogen, while others produce both. Patterns of release vary from patient to patient—some people have slower but normal transit time. Other conditions may produce malabsorption of carbohydrates, such as pancreatic insufficiency and celiac disease.
Breath tests can be particularly helpful for people with IBS told to go on the FODMAP diet. They can help to eliminate specific problem carbohydrates prior to starting a very restrictive diet. If you can isolate the main carbohydrate problem you can eliminate many weeks of trial and error. The tests should be part of a gastroenterologist’s armamentarium but are often not widely available or utilized.
Test for Vitamin and Mineral Deficiencies
My husband does not eat anything that is orange, green, or yellow—otherwise known as vegetables. He’ll eat tomatoes because I told him they were fruit.
(TESS, 29)
Many people take vitamin and mineral supplements because they make them feel healthier. Others use them to supplement a restrictive diet. Several websites and TV personalities suggest easy ways to determine if you are deficient in specific vitamins. One “analysis” includes standing on your right foot for three seconds without losing your balance (to diagnose a B12 deficiency), or pressing your thumb into your breastbone to see if this causes discomfort (to diagnose a vitamin D deficiency). This “testing” ranges from useless to preposterous. It is more likely to uncover a balance disorder and/or leave a black-and-blue mark from pressing too hard.
If you feel that your diet does not contain sufficient amounts of everything your body needs, have your doctor run blood tests for essential vitamins and minerals.
While there are many people in the world suffering from malnutrition and serious vitamin deficiencies, they are rarely the people buying supplements in health food stores. People with malabsorption conditions—celiac disease, inflammatory bowel disease, protein allergies, intestinal