Functional Medicine Gastroenterology: Better Patient Outcomes With Comprehensive Lab Testing

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) states that 60 to 70 million people are impacted by some type of digestive disease. With poor digestive health being linked to systemic "dis-ease" – including cardiovascular disease, mood disorders, sleep disturbances, thyroid dysfunction, autoimmune disease, and infertility – this cannot go unaddressed. 

Functional medicine labs can complement conventional gastroenterological diagnostic labs and imaging by providing deeper insights into the underpinnings of many chronic digestive diseases.

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Understanding Functional Medicine in Gastroenterology

Functional medicine is a patient-centered, systems-oriented approach to healthcare. This healthcare model aims to identify and treat the root causes of disease by examining the interconnected systems within the body. This approach is holistic, emphasizing the role of diet, lifestyle, genetics, and the environment in health and disease.

This paradigm shift moves beyond managing symptoms to investigating and addressing dysfunctions that may contribute to chronic gastrointestinal (GI) issues, such as microbial imbalances, inflammation, and nutrient deficiencies. 

This approach's benefits include preventing the recurrence and chronic progression of GI diseases, improving patient quality of life, and reducing the reliance on pharmacotherapy. 

The Role of Comprehensive Lab Testing in Functional Medicine Gastroenterology

Comprehensive, specialty lab testing provides objective data that reveal underlying causes of GI disorders. Functional medicine labs evaluate biomarkers measured through stool, blood, breath, and urine samples that reflect gut health, inflammation, nutrient levels, and other factors influencing digestive health. These insights allow practitioners to develop more targeted and effective treatment plans.

Key Functional Medicine Labs for Gastroenterology

Selecting the right labs is essential for optimizing patient outcomes. The following labs are particularly relevant in functional gastroenterology.

Comprehensive Stool Analysis

A comprehensive stool analysis (CSA) is designed to assess the ecology and physiology of the GI tract.

Key areas of GI health and function that are analyzed with a CSA include:

• Digestion and absorption
• Gut microbiome diversity and abundance
• Infectious pathogens (bacteria, parasites, fungi, and viruses)
• Immune function and inflammation

Stool analysis helps uncover underlying causes of gastrointestinal symptoms and chronic conditions, such as: 

• Constipation
• Diarrhea
• Blood, mucus, or undigested food in the stool
• Abdominal pain
• Chronic bloating
• Excessive gas
• Unexplained weight loss
• Food intolerances

Examples of Comprehensive Stool Analyses

• GI-MAP by Diagnostic Solutions
• GI Effects Comprehensive Profile - 3 Day by Genova Diagnostics
• GI360 by Doctor's Data

SIBO Testing

Small intestinal bacterial overgrowth (SIBO) is the overgrowth of bacteria in the small intestine. As our understanding of SIBO evolves, we have been able to identify three specific subtypes of SIBO:

• Hydrogen-dominant SIBO
• Intestinal methanogen overgrowth (IMO)
• Intestinal sulfide overproduction (ISO)

SIBO breath tests measure hydrogen, methane, and hydrogen sulfide gases produced by intestinal bacteria and archaea (bacteria-like microorganisms) to diagnose SIBO.

SIBO is a frequent contributor to irritable bowel syndrome (IBS) symptoms and can lead to chronic digestive discomfort and malnutrition (12). Patients with IBS who are diagnosed with and treated for SIBO report improvements in GI symptoms (23).

Examples of SIBO Breath Tests

• SIBO - 3 Hour by Genova Diagnostics
• trio-smart SIBO Breath Test by Gemelli Biotech
• SIBO Breath Test - Glucose by Aerodiagnostics LLC

Adverse Food Reactions

Food allergies are IgE immune-mediated reactions to specific food proteins. They can cause symptoms ranging from mild (urticaria, pruritus) to severe (anaphylaxis). The prevalence of food allergies is approximately 5-10% in children and 1-3% in adults. Common allergens include cow's milk, eggs, peanuts, tree nuts, soy, shellfish, and fish. Symptoms typically occur within minutes of ingestion and can affect the skin, gastrointestinal, respiratory, and cardiovascular systems. (4, 37, 38) 

Examples of Food Allergy Tests

• 96 Food Panel: IgE by US BioTek
• IgE Food Antibodies by Genova Diagnostics

Food sensitivities are less well-defined and delayed reactions to foods mediated by IgG and IgA immune proteins. Symptoms are often nonspecific, including gastrointestinal discomfort, headaches, and fatigue.

Examples of Food Sensitivity Tests

• 96 IgG Food Sensitivity Panel by Alletess Medical Laboratory
• Alcat Test: 250 Food Panel by Cell Science Systems
• FIT 176 by KBMO Diagnostics

Food intolerances are non-immune-mediated adverse reactions, often due to enzymatic deficiencies (e.g., lactose intolerance) or reactions to food chemicals (e.g., histamine intolerance). Symptoms typically include gastrointestinal issues such as bloating, diarrhea, and abdominal pain, and they usually occur within hours of consuming the offending food.

Examples of Food Intolerance Tests

• Lactose Intolerance Breath Test by Aerodiagnostics LLC
• Fructose Malabsorption Breath Test by Commonwealth Diagnostics International, Inc. 

Micronutrient Panel

Chronic gastrointestinal diseases are frequently associated with various nutritional deficiencies due to factors like malabsorption, increased nutrient losses, and dietary restrictions.

For example, deficiencies in iron, vitamin B12, folate, vitamin D, vitamin K, selenium, and zinc are common in patients with inflammatory bowel disease (IBD) due to blood loss, malabsorption, and medication side effects.

Patients with conditions associated with fat malabsorption are at an increased risk of vitamin A, E, D, and K deficiency.

The American Gastroenterological Association (AGA) recommends regular monitoring and appropriate supplementation of these micronutrients to prevent complications and improve patient outcomes.

A micronutrient panel evaluates the levels of essential vitamins and minerals to screen for deficiencies comprehensively. Patients at high risk for deficiencies due to malabsorption syndromes or restrictive diets can benefit from this test for targeted nutrient support.

Intestinal Permeability Markers

Increased intestinal permeability, commonly called "leaky gut," is a condition in which the intestinal lining becomes more permeable than normal, allowing larger molecules (such as undigested food particles, toxins, and pathogens) to pass into the bloodstream. This can lead to systemic inflammation, immune activation, and is implicated in various gastrointestinal and autoimmune disorders. 

Labs that measure intestinal permeability often will use the following biomarkers:

• Zonulin is a protein that regulates the tight junctions between cells in the intestinal wall, which control the passage of substances from the gut into the bloodstream. Elevated levels cause these tight junctions to loosen, making the intestinal barrier more permeable. (41) 
• Lipopolysaccharides (LPS) are endotoxins found in the outer membrane of gram-negative bacteria in the gut. Normally, LPS should remain within the gut; however, when the gut barrier is compromised, LPS can enter the bloodstream and trigger an immune response. 
• Occludin and Claudin Antibodies: Occludin and claudin are structural proteins forming tight junctions between cells in the intestinal lining. Antibodies to these proteins suggest an immune reaction against the gut barrier, indicating that these proteins are being broken down or are compromised. (2)

Examples of Intestinal Permeability Tests

• Gut Barrier Panel by KBMO Diagnostics
• Array 2 by Cyrex Laboratories
• Zonulin by Diagnostic Solutions
• Intestinal Permeability Assessment by Genova Diagnostics 

Genetics Profile

Understanding the genetic and environmental interplay that contributes to disease allows for a more precise approach to disease prevention, diagnosis, and treatment. Genetic predispositions provide the groundwork for certain conditions, but environmental factors like diet, infections, microbiome composition, and lifestyle often determine whether or when a disease manifests and how severe it may become. (40) 

Genetic testing can identify gene variants associated with certain GI conditions, aiding in early risk assessment and differentiation between diseases with overlapping symptoms. Knowing a patient's genetic predisposition can inform the need for further testing and imaging. 

For example, the presence of HLA-DQ2 and HLA-DQ8 genetic variations significantly increases susceptibility to celiac disease. Nearly all individuals with celiac disease carry at least one of these markers (1). In suspected cases of celiac disease, positive HLA-DQ2 or DQ8 results can support the need for confirmatory serologic testing and endoscopic biopsy.

Examples of Genetic Tests

• Celiac, IBS, and Crohn's Assay (CICA) by Cell Science Systems
• Wellness Panel by DNA RX 

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Key Takeaways

• Functional medicine lab testing has the potential to transform the field of gastroenterology by enhancing diagnostic accuracy, allowing for personalized treatment plans, and improving patient outcomes. 
• By incorporating labs like comprehensive stool analysis, SIBO testing, and micronutrient panels, gastroenterologists can address the root causes of disease and reduce symptom recurrence. Adopting these labs into practice can empower patients and provide a more sustainable approach to digestive health management.