All Digestive System Tests

The Myeloperoxidase (MPO) Antibody Test detects autoantibodies against MPO, often associated with ANCA-associated vasculitis, including microscopic polyangiitis and granulomatosis with polyangiitis. Elevated MPO antibodies may indicate inflammation of blood vessels, kidneys, or lungs. Physicians order this blood test to support diagnosis, monitor disease activity, and guide treatment decisions for autoimmune and systemic vasculitis disorders.

The Parietal Cell Antibody Test detects autoantibodies against stomach parietal cells, which produce intrinsic factor and stomach acid. Their presence is strongly associated with pernicious anemia, vitamin B12 deficiency, and autoimmune gastritis. Doctors use this blood test to help diagnose the cause of anemia, investigate digestive issues, and evaluate patients with suspected autoimmune disorders affecting stomach function and nutrient absorption.

The Prealbumin Test measures levels of prealbumin, a protein made by the liver that reflects short-term nutritional status. Low levels may indicate malnutrition, liver disease, inflammation, or chronic illness, while high levels may be linked to kidney disease or steroid use. Doctors use this test to assess protein-calorie nutrition, monitor patients receiving nutritional support, and guide treatment for conditions affecting metabolism and recovery.

The Protein Electrophoresis Random Urine Test analyzes protein distribution in a urine sample to detect abnormal monoclonal or polyclonal proteins. It helps evaluate multiple myeloma, kidney damage, and systemic disorders affecting protein metabolism. This test supports monitoring of urinary protein loss, renal impairment, and plasma cell disorders, offering valuable insight into overall kidney and immune health.

The Protein Total and Albumin Test measures overall protein levels and albumin, the main blood protein made by the liver. Abnormal levels may indicate liver disease, kidney disorders, malnutrition, or chronic inflammation. Doctors order this test for patients with swelling, fatigue, or abnormal lab results. Results provide critical insight into nutritional status, liver and kidney function, and help guide diagnosis and treatment of metabolic or chronic conditions.

The Proteinase-3 Antibody Test detects antibodies against proteinase-3, a neutrophil enzyme associated with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Elevated levels are strongly linked to granulomatosis with polyangiitis and other autoimmune small vessel vasculitides. This test aids in diagnosis, assessing disease activity, and guiding management of systemic inflammatory and autoimmune vascular conditions.

The Prothrombin with INR and Partial Thromboplastin Times Test measures how long blood takes to clot by evaluating PT, INR, and aPTT. Abnormal results may indicate clotting disorders, liver disease, vitamin K deficiency, or risk of bleeding and thrombosis. Doctors use this test to monitor patients on blood thinners like warfarin, assess unexplained bleeding, and evaluate clotting function. It provides critical insight into coagulation and overall blood health.

The Red Blood Cell Count Test measures the number of red blood cells circulating in the blood, essential for evaluating oxygen transport and overall health. Abnormal levels may indicate anemia, iron deficiency, vitamin B12 or folate deficiency, dehydration, or bone marrow disorders. This test provides critical insight into hematologic health and is often part of a complete blood count to guide further evaluation.

The Reducing Substances Stool Test measures sugars in stool to assess carbohydrate digestion and absorption. Elevated levels can point to lactose intolerance, hereditary enzyme deficiencies, or gastrointestinal conditions affecting nutrient breakdown. By identifying unabsorbed carbohydrates, this test helps clinicians evaluate chronic diarrhea, bloating, abdominal discomfort, or pediatric feeding problems, offering valuable information about intestinal and metabolic health.

The Reticulocyte Count Test measures immature red blood cells (reticulocytes) to evaluate bone marrow function and red cell production. High levels may indicate blood loss, hemolytic anemia, or recovery from treatment, while low levels may suggest bone marrow failure, nutritional deficiencies, or chronic disease. Doctors use this test to assess anemia, monitor therapy, or track recovery. Results provide key insight into red blood cell health and overall hematologic function.

The Rheumatoid Factor (RF) Test measures RF antibodies in blood to help diagnose rheumatoid arthritis and other autoimmune conditions. High RF levels may indicate rheumatoid arthritis, Sjögren’s syndrome, or other connective tissue diseases, though they can also appear in some infections. Doctors order this test to investigate joint pain, stiffness, or swelling. Results provide important insight into autoimmune activity, joint health, and inflammatory disease management.

The Saccharomyces cerevisiae IgA Antibodies Test detects IgA antibodies against baker’s or brewer’s yeast, often elevated in Crohn’s disease. This test helps distinguish inflammatory bowel disease from ulcerative colitis and other gastrointestinal disorders. Doctors use results with clinical evaluation and other markers to aid diagnosis, monitor disease activity, and guide ongoing management of digestive and autoimmune health conditions.

The Saccharomyces cerevisiae IgG Antibodies Test measures IgG antibodies against baker’s or brewer’s yeast, often associated with autoimmune and gastrointestinal disorders. Elevated IgG levels are commonly linked to Crohn’s disease and may help differentiate it from ulcerative colitis. This test supports evaluation of immune response, gastrointestinal inflammation, and monitoring of conditions tied to yeast-related antibody activity.

The Sed Rate Test, also called the ESR Test, measures how quickly red blood cells settle in a sample of blood. A faster rate may signal inflammation caused by infections, autoimmune diseases, arthritis, or other chronic conditions. Doctors use this test to investigate unexplained fever, joint pain, or muscle aches, and to monitor inflammatory disorders such as lupus or rheumatoid arthritis. The Sed Rate Test provides important insight into overall inflammatory activity.

The Serotonin Test measures levels of serotonin, a neurotransmitter that regulates mood, sleep, and digestion. Abnormal results may suggest carcinoid tumors, which overproduce serotonin, or disorders affecting mental and physical health. Doctors order this test for patients with flushing, diarrhea, or rapid heartbeat. Results provide key insight into serotonin metabolism, helping diagnose carcinoid syndrome and guide treatment for related conditions.

The Sickle Cell Screen detects abnormal hemoglobin S in blood to identify sickle cell trait or sickle cell disease. A positive screen suggests the presence of sickle hemoglobin, which may require confirmatory testing. Doctors order this test for newborn screening, genetic counseling, or evaluating anemia, pain crises, or family history of hemoglobin disorders. Results provide key insight into sickle cell status, red blood cell health, and hereditary blood conditions.

The Soluble Transferrin Receptor Test evaluates blood sTfR concentration to assess iron metabolism and red blood cell production. It is particularly useful for differentiating iron deficiency anemia from anemia of chronic disease, since sTfR remains stable in the presence of inflammation. This test helps clinicians identify hidden iron deficiency, monitor treatment response, and evaluate hematopoietic activity in various clinical contexts.

The T3 Free Test measures free triiodothyronine (T3), the active thyroid hormone not bound to proteins, to assess thyroid function. It helps diagnose hyperthyroidism, hypothyroidism, goiter, and pituitary disorders. Doctors order this test to evaluate symptoms like fatigue, weight changes, anxiety, or irregular heartbeat and to monitor thyroid replacement or antithyroid therapy. The Free T3 Test provides key insight into metabolism, energy regulation, and overall endocrine health.

The T4 Free Test measures the level of free thyroxine (T4) in blood, the active thyroid hormone not bound to proteins. It helps diagnose thyroid disorders such as hypothyroidism, hyperthyroidism, and goiter, as well as pituitary conditions affecting hormone regulation. Doctors use this test to evaluate symptoms like fatigue, weight changes, hair loss, or irregular heartbeat and to monitor thyroid replacement or antithyroid therapy, providing insight into metabolic and endocrine health.