What is the workup and treatment for a 31-year-old female with steatorrhea (oily stool) and weight loss?

Workup and Management of Steatorrhea and Weight Loss in a 31-Year-Old Female

Begin with screening for celiac disease, pancreatic exocrine insufficiency, and small bowel malabsorption as these are the most common treatable causes of steatorrhea with weight loss in this age group. 1

Initial Diagnostic Workup

Essential Laboratory Tests

Order the following blood tests immediately to identify the underlying cause:

• Anti-tissue transglutaminase antibodies (IgA) with total IgA level to screen for celiac disease, which commonly presents with steatorrhea and weight loss in young adults 1
• Complete blood count to assess for anemia (iron, B12, or folate deficiency from malabsorption) 1
• Comprehensive metabolic panel including albumin to evaluate nutritional status and protein-energy malnutrition 1
• Thyroid-stimulating hormone (TSH) to exclude hyperthyroidism as a cause of weight loss and diarrhea 1
• Fasting glucose to screen for diabetes, which can cause autonomic neuropathy and malabsorption 1

Nutritional Deficiency Assessment

If steatorrhea is confirmed, check fat-soluble vitamin levels and micronutrients:

• Vitamins A, E, D, and INR (for vitamin K status) 1
• Iron studies (ferritin, serum iron) 1
• Vitamin B12 and red blood cell folate 1
• Magnesium, zinc, copper, and selenium 1

Stool Studies

Obtain fecal elastase-1 as the preferred non-invasive test for pancreatic exocrine insufficiency:

• **Fecal elastase-1 levels <100 μg/g indicate severe pancreatic insufficiency**, 100-200 μg/g suggests mild-to-moderate insufficiency, and >200 μg/g is normal 1
• This test requires only a single 100 mg stool sample, is unaffected by enzyme replacement therapy, and has replaced invasive pancreatic function tests 1
• Do not perform this test during acute diarrhea, as watery stool can falsely lower elastase levels 1

Screen for infectious causes:

• Stool culture, ova and parasites (including Giardia lamblia antigen) 2
• Consider testing for small intestinal bacterial overgrowth if initial workup is negative 1

Imaging Studies

Order abdominal imaging to evaluate for structural abnormalities:

• CT enterography or MR enterography to assess for small bowel Crohn's disease, which can present with steatorrhea and weight loss in young adults 1, 2
• Plain abdominal radiograph if intestinal dysmotility or pseudo-obstruction is suspected (look for dilated bowel loops) 1
• Consider chest X-ray if autoimmune or paraneoplastic causes are suspected 1

Endoscopic Evaluation

Perform upper endoscopy with duodenal biopsies if celiac serology is positive or if initial workup is unrevealing:

• Obtain at least 4-6 duodenal biopsies to diagnose celiac disease, as patchy involvement can be missed with fewer samples 2
• Biopsies can also identify Whipple's disease, giardiasis, and other small bowel pathology 2
• Consider colonoscopy with biopsies if microscopic colitis is suspected (can cause weight loss despite being primarily a diarrheal illness) 2

Specific Diagnoses and Treatment

Celiac Disease

If anti-tissue transglutaminase is positive and duodenal biopsies show villous atrophy:

• Initiate strict lifelong gluten-free diet as the only effective treatment 2
• Refer to dietitian experienced in celiac disease management 2
• Supplement deficient vitamins and minerals identified on initial testing 1

Pancreatic Exocrine Insufficiency

If fecal elastase-1 is <100 μg/g, start pancreatic enzyme replacement therapy:

• Prescribe enteric-coated pancrelipase (e.g., CREON) at an initial dose of 500 lipase units/kg/meal for adults 3
• Administer enzymes with meals and approximately half the meal dose with snacks 3
• Do not exceed 2,500 lipase units/kg/meal or 10,000 lipase units/kg/day without further investigation 3
• Titrate dose based on clinical response (reduction in steatorrhea, weight gain) and consider adding a proton pump inhibitor if response is inadequate, as acidic intestinal pH can inactivate lipase 4
• Enteric-coated minimicrospheres are preferred over non-coated preparations to avoid acid-mediated enzyme inactivation 4

Small Bowel Crohn's Disease

If CT/MR enterography shows small bowel inflammation or stricturing:

• Refer to gastroenterology for initiation of immunosuppressive therapy 1
• Consider nutritional support with polymeric enteral nutrition if malnutrition is severe 1
• Monitor for complications including strictures, fistulas, and bacterial overgrowth 1

Giardiasis

If Giardia lamblia is identified on stool testing:

• Treat with metronidazole or tinidazole 2
• Recheck stool after treatment to confirm eradication 2

Critical Pitfalls to Avoid

Do not dismiss steatorrhea as irritable bowel syndrome in a patient with weight loss:

• Weight loss is an alarm feature that mandates investigation for organic disease 1
• IBS does not cause steatorrhea or significant weight loss 1

Do not start pancreatic enzyme replacement empirically without confirming pancreatic insufficiency:

• Fecal elastase-1 testing is simple, non-invasive, and should be performed before initiating expensive enzyme therapy 1
• Empiric treatment may delay diagnosis of other treatable conditions 1

Do not check celiac serology in patients already on a gluten-free diet:

• Antibody levels normalize on a gluten-free diet, leading to false-negative results 2
• If the patient has already eliminated gluten, proceed directly to endoscopy with biopsies or perform HLA-DQ2/DQ8 testing 2

Do not overlook nutritional deficiencies while pursuing the underlying diagnosis:

• Severe vitamin deficiencies (especially fat-soluble vitamins) can cause significant morbidity and should be repleted immediately 1
• Protein-energy malnutrition increases mortality risk and requires aggressive nutritional support 1

Do not use sustained-release or delayed-release medications in patients with suspected malabsorption:

• These formulations require adequate small bowel transit time and absorptive capacity 1
• Use liquid formulations or immediate-release tablets when possible 1