Colon (Intestine)

The colon (large intestine) absorbs water, forms stool, and hosts the gut microbiome. When the colon is inflamed, infected, bleeding, or not absorbing well, targeted stool and blood tests can clarify what’s going on. A proactive approach begins with noninvasive stool markers—such as fecal calprotectin or lactoferrin—to help distinguish inflammatory bowel disease (IBD) from irritable bowel syndrome (IBS). For bleeding risk or screening, stool occult blood tests (especially FIT) and stool DNA–FIT assess for hidden blood and abnormal DNA. When infection is suspected, a GI pathogen PCR panelC. difficile toxin/PCR, and ova & parasites testing can identify causes fast.

Blood tests—CRP/ESRCBCCMP, and iron studies—add context on inflammation, anemia, protein status, and electrolytes. Lab results guide next steps but do not replace a clinician’s exam, imaging, or colonoscopy when indicated.

Signs, Symptoms & Related Situations

  • Digestive: diarrhea or constipation, urgency, mucus or blood in stool, abdominal pain, bloating, excessive gas

  • Systemic: fever, fatigue, unintended weight loss

  • Malabsorption clues: iron-deficiency anemia, low albumin, vitamin deficiencies

  • Infectious risk: recent travel, undercooked food, antibiotic exposure (C. difficile risk)

  • When to seek urgent care: severe rectal bleeding, black/tarry stools, high fever with dehydration, severe abdominal pain, or fainting
    All symptoms should be evaluated by a qualified clinician.

Why These Tests Matter

What testing can do

  • Help separate inflammatory vs. non-inflammatory causes of bowel symptoms

  • Detect occult bleeding and screen for colorectal cancer (stool-based tests)

  • Identify infectious pathogens quickly to guide care

  • Provide baselines and trends for monitoring IBD activity and nutritional impact

What testing cannot do

  • Replace a colonoscopy when visualization or biopsy is needed

  • Diagnose the exact cause of pain without clinical evaluation

  • Serve as population screening for all conditions—use tests for the right question and window

What These Tests Measure (at a glance)

  • Fecal Calprotectin / Fecal Lactoferrin: neutrophil proteins that rise with intestinal inflammation (IBD signal). Caveat: elevations can occur with infection, NSAIDs; use trends and context.

  • FIT (Fecal Immunochemical Test): stool hemoglobin for hidden blood; preferred for colorectal cancer screening. Caveat: positive FIT → diagnostic colonoscopy; single negatives don’t rule out symptoms.

  • Stool DNA–FIT: combines occult blood with DNA markers of colorectal neoplasia. Caveat: positive test → colonoscopy; intervals differ from FIT.

  • Occult Blood (Guaiac): older blood screen; diet/meds can affect results. Caveat: FIT is generally preferred.

  • GI Pathogen PCR Panel: detects common bacteria, viruses, parasitesCaveat: interpret with symptoms; some positives reflect carriage.

  • C. difficile Toxin/PCR: evaluates antibiotic-associated diarrheaCaveat: test only loose stools; colonization is possible.

  • Ova & Parasites / Stool Culture: targeted when travel or specific exposure is likely. Caveat: multiple specimens may be needed.

  • Fecal Fat / Pancreatic Elastase: screens for fat malabsorption and exocrine pancreatic function when steatorrhea is present.

  • CRP / ESR (blood): systemic inflammation markers that correlate with IBD activity. Caveat: nonspecific—use with stool markers.

  • CBC, CMP, Iron Studies, Vitamin D/B12/Folate: anemia, electrolytes, albumin, and nutrient status in chronic GI disease.

How the Testing Process Works

  1. Start with the question: inflammation vs IBS, bleeding risk/screening, or infection—choose stool tests that match the goal.

  2. Collect properly: follow kit instructions (no urine/water in stool containers; observe timing/transport).

  3. Add bloodwork for context: CRP/ESR, CBC, CMP, and iron/nutrient panels as directed.

  4. Review results securely: most stool/blood tests post in a few days.

  5. Plan next steps: your clinician may recommend colonoscopy, imaging, or treatment based on combined findings.

Interpreting Results (General Guidance)

  • High fecal calprotectin/lactoferrin favors organic inflammation (e.g., IBD) over IBS; repeat or escalate to colonoscopy per clinician guidance.

  • Positive FIT or stool DNA–FIT requires diagnostic colonoscopy—do not repeat stool testing instead.

  • Positive GI pathogen/C. difficile suggests infection; negative tests with ongoing symptoms may prompt further work-up.

  • CRP/ESR up + anemia/low albumin support active disease; falling values indicate improvement.
    Always interpret results with a qualified healthcare professional.

Choosing Panels vs. Individual Tests

  • Inflammation vs IBS: Fecal calprotectin (± lactoferrin) + CRP/ESR; add CBC/CMP for impact.

  • Bleeding/screening question: FIT or stool DNA–FIT (per screening strategy); positive results → colonoscopy.

  • Infection suspected: GI pathogen PCR panel ± C. difficile; consider O&P/culture with travel or persistent diarrhea.

  • Malabsorption/weight loss: Fecal fat or pancreatic elastase, plus CBC, iron, B12, folate, vitamin D, CMP.

  • IBD monitoring: Fecal calprotectin trends + CRP/ESRCBCCMP, and iron/vitamin D.

FAQs

Do stool tests replace colonoscopy?
No. Positive screening tests or alarm symptoms require diagnostic colonoscopy.

What if calprotectin is borderline?
Repeat testing and clinical context matter; your clinician may add lactoferrin, CRP/ESR, or proceed to colonoscopy.

Can I do FIT if I have symptoms now?
FIT is a screening tool; new rectal bleeding or alarm symptoms need clinical evaluation, often with colonoscopy.

How quickly do GI pathogen results return?
PCR panels often post within 1–2 days; classic cultures and O&P can take longer.

Why add blood tests to stool tests?
They show inflammation, anemia, and nutrition—key for staging severity and tracking recovery.

Do antibiotics affect results?
Yes. Recent antibiotics can change pathogen results and fecal markers; tell your clinician.

Internal Links & Cross-References

  • Digestive System Tests Hub

  • Celiac Disease

  • Inflammatory Bowel Disease (IBD)

  • Irritable Bowel Evaluation

  • H. pylori

  • Liver & Pancreas Tests

  • Key Lab Tests: Fecal Calprotectin • Fecal Lactoferrin • FIT (Fecal Immunochemical Test) • Stool DNA–FIT • GI Pathogen PCR Panel • C. difficile Toxin/PCR • Ova & Parasites • Stool Culture • Fecal Fat • Pancreatic Elastase • CRP • ESR • CBC • CMP • Iron Studies • Vitamin D/B12/Folate

References

  1. American College of Gastroenterology. Guidelines on the Management of Inflammatory Bowel Disease and Acute Diarrheal Infections.

  2. American Gastroenterological Association. Technical Review on Fecal Calprotectin and Lactoferrin in IBD.

  3. U.S. Preventive Services Task Force. Colorectal Cancer: Screening Recommendation.

  4. Infectious Diseases Society of America. Infectious Diarrhea and C. difficile Guidelines.

  5. National Institute for Health and Care Excellence. Faecal Calprotectin to Differentiate IBD from IBS.

  6. American Society for Clinical Pathology. Stool Testing Utilization for GI Pathogens.

  7. Centers for Disease Control and Prevention. Traveler’s Diarrhea and Foodborne Pathogens.

Available Tests & Panels

Your colon (intestine) test menu is pre-populated in the Ulta Lab Tests system. Use filters to select inflammation markers (fecal calprotectin/lactoferrin), bleeding/screening tests (FIT or stool DNA–FIT), infection panels (GI pathogen PCR, C. difficile, O&P), and blood context labs (CRP/ESR, CBC, CMP, iron/nutrients). Review all results with your clinician.

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Most Popular

The CA 19-9 Test measures levels of carbohydrate antigen 19-9 in blood, a tumor marker often elevated in pancreatic cancer and sometimes in bile duct, colorectal, or liver cancers. While not used alone for diagnosis, it helps monitor treatment, track disease progression, and detect recurrence. Elevated CA 19-9 may also occur in noncancerous conditions. Doctors use this test to support cancer management and guide therapy decisions.

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Also Known As: CA 19-9 Tumor Marker, Cancer Antigen 19-9 Test

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The CEA Test measures carcinoembryonic antigen levels in blood, a protein that may be elevated in certain cancers, especially colorectal, pancreatic, lung, breast, or ovarian cancer. It is not used alone for diagnosis but helps monitor cancer treatment, detect recurrence, and track disease progression. Elevated CEA can also occur in noncancerous conditions. Doctors use this test to support therapy decisions and provide insight into cancer management.

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Also Known As: Carcinoembryonic Antigen Test

The Fecal Globin by Immunochemistry Test detects hidden (occult) blood in stool using antibodies that identify human globin protein. This test helps screen for colorectal cancer, polyps, ulcers, and gastrointestinal bleeding. Doctors order it when patients have anemia, abdominal pain, or changes in bowel habits. Results provide early detection of digestive tract bleeding, guiding further evaluation with colonoscopy or other diagnostic procedures.

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Also Known As: Fecal Immunochemical Test, Fecal Occult Blood Test, Stool Occult Blood Test, FIT Test, FOBT

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The Immunoglobulin E (IgE) Test measures IgE antibody levels in blood to evaluate allergic reactions, asthma, and immune response. Elevated IgE may indicate allergies to food, pollen, or other triggers, as well as eczema or parasitic infections. Doctors order this test to investigate symptoms like hives, sneezing, or wheezing and to guide allergy treatment. Results provide vital insight into immune health, allergic sensitivity, and overall diagnostic care.

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Also Known As: Immunoglobulin E Test, Immunoglobulin E Antibody Test, IgE Antibody Test

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The Immunoglobulin G (IgG) Test measures IgG antibody levels in blood to assess immune system function and long-term response to infections. Low IgG may indicate immune deficiencies or recurrent infections, while high levels may signal chronic inflammation, autoimmune disease, or certain infections. Doctors use this test to evaluate unexplained illness, monitor immune disorders, or assess overall immunity. Results provide vital insight into immune health and disease management.

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Also Known As: Immunoglobulin G Test, Immunoglobulin G Antibody Test, IgG Antibody Test

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The Immunoglobulin M (IgM) Test measures IgM antibody levels in blood to evaluate immune response and early defense against infections. High IgM may indicate recent or acute infections, autoimmune disease, or certain blood disorders, while low levels may suggest immune deficiency. Doctors order this test to investigate recurrent infections, unexplained inflammation, or suspected immune problems. Results provide vital insight into antibody health, immune status, and diagnostic care.

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Also Known As: Immunoglobulin M Test, Immunoglobulin M Antibody Test, IgM Antibody Test

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The Immunoglobulin A (IgA) Test measures IgA antibody levels in blood to evaluate immune system health and mucosal defense in the respiratory and digestive tracts. Low IgA may indicate immune deficiency, celiac disease, or recurrent infections, while high levels may suggest autoimmune disorders, liver disease, or chronic inflammation. Doctors use this test to assess unexplained illness or immune imbalance. Results provide key insight into antibody function and overall immunity.

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Also Known As: Immunoglobulin A Test, Immunoglobulin A Antibody Test, IgA Antibody Test

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The Oxalic Acid 24 Hour Urine Test measures urinary oxalate excretion to evaluate risk for kidney stone formation and metabolic disorders. Elevated oxalic acid may indicate primary or secondary hyperoxaluria, malabsorption syndromes, or dietary imbalance. By tracking oxalate output over 24 hours, this test provides valuable insight into urinary health, metabolic function, and conditions that impact calcium oxalate stone development.

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Nearly 150,000 adults living in the United States get diagnosed with colorectal cancer every year. Even more people get diagnosed with other colon and intestinal diseases.

Gastrointestinal problems are common, so you shouldn't feel embarrassed if you're experiencing signs and symptoms. The best things that you can do is educate yourself and order colon blood tests. Both of these steps will help you learn more about your body and how to care for it.

Keep reading to learn more about colon and intestinal diseases and lab tests for them.

What Are the Colon and Intestinal Diseases?

Colon and intestinal diseases are a collection of ailments that affect the colon, which is a part of your digestive system. The colon is a long, hollow tube at the end of the digestive tract that helps your body make and store stool before its removal from your system.

There are many types of colon and intestinal disorders:

  • Irritable bowel syndrome
  • Irritable bowel disease (ulcerative colitis or Chron's disease)
  • Colorectal cancer
  • Colonic polyps
  • Diverticulitis
  • Celiac disease

The signs, symptoms, and treatment for each one of the conditions vary.

No matter the condition, prompt care is important. The sooner that a patient is diagnosed, the sooner they can get treatment.

Risk Factors for Colon and Intestinal Diseases

Most colon and intestinal diseases are genetic, which means you're at greater risk if a close relative has a colon disease. With family history, there are a few other risk factors to take into consideration:

  • Age - problems with the colon become more prominent with age due to alteration of the colon over time
  • Race or ethnicity - colon and intestinal diseases are more common in Caucasian individuals
  • Cigarette smoking - smoke can harm your digestive tract and make developing cancer more likely
  • NSAID consumption - taking nonsteroidal anti-inflammatory drugs (NSAIDs) can increase your risk for developing colon-related disorders

You can't control your genetics, but you can take care of your gut health to the best of your ability. By eating right and avoiding things like cigarette smoke and NSAIDs, you can lessen the chance that you'll develop colon and intestinal diseases.

Causes of Colon and Intestinal Diseases

Most diseases of the colon occur with an imbalance of the bacteria that live in the digestive tract. Too much harmful bacteria can cause problems with your large intestine, which can lead to disorders and diseases.

Sometimes, this bacteria can cause polyps to form. Other times, an overactive immune system response will occur. The disease process will depend on the kind of intestinal disease that is forming.

By eating a balanced diet, you can mitigate some of these problems. However, the composition of your gut comes mainly from a genetic predisposition. Therefore, some patients can only control an existing disease rather than prevent the disease altogether.

What Are the Signs and Symptoms of Colon and Intestinal Diseases?

The best way to determine whether there's a problem with your digestive system is to note how the system is working, which means that you need to know your abdomen and your stool very well.

You should have an idea of what it feels like when you're hungry, full, or bloated. Likewise, you should know when you're having abnormal abdominal pain. When it comes to your stool, you should note the color and consistency so that you can determine when there's a change in your stool.

Here are the signs and symptoms of colon and intestinal diseases that you should look out for:

  • A change in your bowel habits
  • Blood on or in your stool
  • Abdominal pain
  • Excessive gas
  • Abnormally shaped stool
  • Stool of an abnormal color
  • Inability to completely void stool
  • Fatigue
  • Unintended/Unexplained weight loss
  • Anemia

If you're experiencing any of these signs or symptoms, you need to see your healthcare provider. They can order the right tests and help you determine your diagnosis and subsequent course of treatment.

The earlier you get a diagnosis, the better.

How Are Colon and Intestinal Diseases Diagnosed?

Getting a diagnosis related to the digestive system can be a long process. It's difficult for physicians to look inside the body, especially considering that most signs and symptoms occur during or after food consumption.

To gather as much information as possible, physicians will order several tests and perform a few procedures:

  • Colon lab tests to look for anemia or infection
  • Stool studies to look for blood or organisms
  • Upper endoscopy
  • Colonoscopy
  • Flexible sigmoidoscopy
  • Capsule endoscopy
  • Balloon-assisted enteroscopy
  • Abdominal x-ray
  • CT scan of the abdomen
  • MRI of the pelvis

With all of this information, the healthcare provider can make an accurate diagnosis and an appropriate treatment plan.

The Lab Tests to Screen, Diagnose, and Monitor Colon and Intestinal Diseases

The colon tests associated with the diagnosis of intestinal diseases are extensive. Healthcare providers need to gather as much information as possible. At Ulta Lab Tests, we offer four panels that look for biomarkers of digestive health:

Each one of these panels looks for relevant biomarkers. Depending on the lab panel you choose, more specific tests will be done to look at your digestive health.

No matter the panel you decide on, you're going to gain valuable information about your health.

Get Your Colon Blood Tests at Ulta Lab Tests

If you believe you may have a colon or intestinal disease, you need to get colon blood tests. The sooner your healthcare provider can diagnose these conditions, the better your prognosis will be.

Luckily, Ulta Lab Tests offers the colon lab tests that you need. Ulta Lab Tests offers highly accurate and reliable tests so that you can make informed decisions about your health.

Here are some of the benefits that you can get if you order from Ulta Lab Tests:

  • You'll get secure and confidential results
  • You don't need health insurance
  • You don't need a physician's referral
  • You'll get affordable pricing
  • We offer a 100% satisfaction guarantee

Order your colon blood tests today, and we'll provide your results to you securely and confidentially online in 24 to 48 hours for most tests.

Take control of your health with Ulta Lab Tests today!