What is the diagnosis and treatment for a teenager with abdominal pain, steatorrhea, and malabsorption symptoms?

Diagnosis: Cystic Fibrosis with Exocrine Pancreatic Insufficiency

This 15-year-old girl with chronic steatorrhea (loose, greasy, foul-smelling stools), malabsorption, growth failure (height and weight below normal for age), and dermatologic findings most likely has cystic fibrosis (CF) with exocrine pancreatic insufficiency (EPI), and requires immediate sweat chloride testing followed by CFTR mutation analysis for confirmation. 1

Clinical Presentation Strongly Suggests CF

The constellation of findings is classic for CF:

• Gastrointestinal manifestations: The year-long history of steatorrhea (loose, greasy, foul-smelling stools), bloating, and abdominal pain with hyperactive bowel sounds indicates severe fat malabsorption from pancreatic insufficiency 1

• Growth failure: Height of 149.9 cm and weight of 37.6 kg in a 15-year-old represents significant growth retardation, a hallmark of untreated CF with malabsorption 1, 2

• Dermatologic findings: The facial erythema, puffiness, and hyperpigmentation likely reflect fat-soluble vitamin deficiencies (particularly vitamin A and E) and protein-calorie malnutrition from chronic malabsorption 1, 2

• Age at presentation: While CF is increasingly diagnosed through newborn screening, adolescent diagnosis still occurs in patients with milder phenotypes or those who were not screened 3

Diagnostic Algorithm

Step 1: Sweat Chloride Test (Gold Standard)

• Perform pilocarpine iontophoresis with sweat collection - this remains the most reliable diagnostic test for CF 3
• Sweat chloride >60 mmol/L confirms CF diagnosis 1, 3
• Values 30-60 mmol/L are intermediate and require further evaluation 3
• This patient's clinical presentation (chronic respiratory symptoms plus malabsorption) makes CF highly likely 3

Step 2: CFTR Mutation Analysis

• Identify specific CFTR mutations to confirm diagnosis and guide mutation-specific therapies 3
• Birth prevalence varies by ethnicity: 1/2,500-3,500 in non-Hispanic whites, 1/4,000-10,000 in Hispanics, 1/15,000-20,000 in non-Hispanic blacks 1
• The ΔF508 mutation is most common and associated with pancreatic insufficiency 1

Step 3: Assess Pancreatic Function

• Fecal elastase-1 test on semi-solid stool: FE-1 <100 μg/g confirms EPI; <50 μg/g indicates severe EPI 1
• Over 80% of CF patients have pancreatic insufficiency at diagnosis, increasing to >90% with age 1
• Pancreatic insufficiency causes the steatorrhea, fat-soluble vitamin deficiencies, and growth failure seen in this patient 1

Step 4: Evaluate for Complications

• Fat-soluble vitamin levels (A, D, E, K) - deficiencies are common and contribute to clinical manifestations 1, 2
• Nutritional assessment including calcium, magnesium, zinc, thiamine, and folic acid 4
• Pulmonary evaluation - chronic respiratory symptoms are expected in CF 1
• Screen for CF-related diabetes - affects at least 25% of CF adults and inversely correlates with prognosis 2

Treatment Protocol

Immediate Management: Pancreatic Enzyme Replacement Therapy (PERT)

Initiate CREON (pancrelipase) immediately upon diagnosis confirmation 5:

• Starting dose for adolescents: 500 lipase units/kg/meal (approximately 18,750-20,000 units per meal for this 37.6 kg patient) 5
• With snacks: Half the meal dose (approximately 9,000-10,000 units) 5
• Administration: Take with all meals and snacks; swallow capsules whole or open and sprinkle on acidic food (pH ≤4.5) like applesauce 5

Dose titration 5:

• If malabsorption persists, increase gradually
• Maximum dose: 2,500 lipase units/kg/meal or 10,000 lipase units/kg/day 5, 6
• For this patient: maximum 94,000 units/meal or 376,000 units/day
• Critical warning: Do not exceed these limits without investigation due to risk of fibrosing colonopathy 5, 6

Adjunctive Therapy Considerations

Gastric acid suppression remains controversial 7, 8:

• Duodenal hyperacidity can impair pancreatic enzyme function in CF 8
• However, a 2025 randomized trial showed no consistent improvement in fat absorption with omeprazole 7
• Consider trial of proton pump inhibitor only if inadequate response to appropriate PERT dosing 8

Nutritional Rehabilitation

Fat-soluble vitamin supplementation 1, 2:

• Vitamin A, D, E, and K supplementation is mandatory
• Monitor levels and adjust doses accordingly
• Vitamin D deficiency contributes to osteopenia, which is common in CF 2

Dietary management 2:

• High-calorie, high-fat diet to compensate for malabsorption
• Energy requirements may be 120-150% of normal due to increased metabolic demands 2
• Work with expert dietitian for individualized nutrition plan 2

Additional micronutrients 4:

• Calcium, magnesium, zinc, thiamine, and folic acid as deficiencies are identified
• Essential fatty acid supplementation may be needed 2

Critical Pitfalls to Avoid

1. Do not delay diagnosis: This patient has had symptoms for a year - immediate sweat testing is essential 1, 3

2. Do not exceed maximum PERT doses: Doses >10,000 lipase units/kg/day are associated with fibrosing colonopathy, particularly with Eudragit-containing preparations 6

3. Do not assume PERT failure without investigation: If symptoms persist despite appropriate PERT dosing, evaluate for:

   • Non-adherence to therapy 6
   • Incorrect administration technique 5
   • Concurrent celiac disease 1
   • Small intestinal bacterial overgrowth 1
   • CF-related diabetes 2

4. Do not ignore pulmonary manifestations: CF is a multi-system disease requiring comprehensive care at a CF reference center 1, 3

5. Do not forget genetic counseling: Once diagnosis is confirmed, family members should be offered genetic testing and counseling 1

Expected Outcomes with Treatment

With appropriate PERT and nutritional support 1, 6:

• Resolution of steatorrhea and gastrointestinal symptoms
• Improvement in nutritional status and growth velocity
• Correction of vitamin deficiencies
• Improved quality of life
• Better long-term pulmonary outcomes (nutritional status directly correlates with survival) 2

This patient requires immediate referral to a CF center for comprehensive multidisciplinary care 3, as proper management significantly impacts both morbidity and mortality in CF.