A 27-year-old woman visits her primary care clinic reporting six months of frequent, bulky, and foul-smelling bowel movements associated with abdominal bloating and profound fatigue. Over this timeframe, she has experienced an unintentional weight loss of 3.5 kg (7.7 lb). Her medical history is significant for type 1 diabetes mellitus. Vital signs are stable. Physical examination reveals conjunctival pallor but no abdominal tenderness. Laboratory results show a hemoglobin of 10.2 g/dL and a mean corpuscular volume of 74 fL. Suspecting a specific autoimmune enteropathy, the physician decides to initiate a diagnostic workup. Which of the following is the most appropriate initial step in the evaluation of this patient?
- Measurement of serum IgA tissue transglutaminase antibodiesAnswer
- BInitiation of an empiric gluten-free diet followed by symptom reassessment
- CImmediate upper gastrointestinal endoscopy with duodenal biopsy
- DStool microscopy for ova and parasites with empiric oral metronidazole
- EMeasurement of serum thyroid-stimulating hormone levels
Answer
Measurement of serum IgA tissue transglutaminase antibodies
The correct approach for diagnosing celiac disease begins with serologic screening using IgA anti-tissue transglutaminase (tTG) antibodies, typically ordered alongside a total IgA level to exclude selective IgA deficiency. This patient's presentation of chronic diarrhea, weight loss, and microcytic anemia, especially in the context of another autoimmune condition (type 1 diabetes mellitus), is highly suspicious for celiac sprue. Testing must be performed while the patient is actively consuming a gluten-containing diet to ensure that the autoantibodies are actively being produced and are measurable.
Step-by-Step Solution
Key Concept
The most appropriate initial diagnostic test for celiac disease is the measurement of serum IgA tissue transglutaminase (tTG) antibodies while the patient is on a gluten-containing diet.