What is the approach to management for a 16-year-old male with intermittent abdominal pain, negative transglutaminase (tissue transglutaminase) test, history of mucus, no blood, and possible Irritable Bowel Syndrome (IBS) with identified food triggers and normal basic blood work?

Management Approach for a 16-Year-Old Male with Suspected IBS

Begin with patient education emphasizing a positive diagnosis of IBS based on symptoms alone, followed by a stepwise approach starting with lifestyle modifications and dietary interventions, reserving pharmacotherapy for persistent symptoms. 1, 2

Confirm the Diagnosis and Provide Education

Since the basic workup is complete (negative celiac serology, normal blood work, no alarm features), you can confidently diagnose IBS without further testing. 1, 2

Key points to communicate to the patient:

• Explain that IBS is a disorder of gut-brain interaction where the gut becomes hypersensitive, causing real physical symptoms triggered by stress, certain foods, and illness 1
• Emphasize that this is not associated with increased cancer risk or mortality, and symptoms are taken seriously 1
• Set realistic expectations: complete cure is unlikely, but substantial improvement in symptoms and quality of life is achievable 1
• Avoid extensive additional testing, as the diagnosis is secure when Rome IV criteria are met without alarm features 1, 2

First-Line Management: Lifestyle and Dietary Modifications

Lifestyle Changes

• Recommend regular physical activity as it provides significant symptom management benefits 1, 2
• Address sleep hygiene and stress management through self-help resources, apps, or handouts 3

Initial Dietary Approach

Start with standard dietary advice before considering restrictive diets: 3, 1

• Identify and reduce excessive intake of lactose (if consuming >280 ml milk/day), fructose, sorbitol, caffeine, and alcohol 3, 1, 2
• Since the patient has identified food triggers, work with him to document these systematically using a symptom diary 3
• Add soluble fiber supplementation (ispaghula/psyllium) starting at 3-4 g/day, gradually increasing to avoid bloating 1, 2, 4

Critical pitfall to avoid: Do not recommend IgG-based food allergy testing, as true food allergy is rare in IBS 4

Second-Line Management: Pharmacotherapy (If Symptoms Persist After 4-6 Weeks)

For Abdominal Pain

• Use antispasmodics (dicyclomine) as first-line therapy, particularly when pain is meal-related 1, 2
• If pain persists or is frequent/severe, consider low-dose tricyclic antidepressants (amitriptyline 10 mg once daily, titrating to 30-50 mg) 1, 2

For Diarrhea (if predominant)

• Loperamide 2-4 mg up to four times daily is highly effective for reducing loose stools, urgency, and fecal soiling 3, 2

For Constipation (if predominant)

• Osmotic laxatives (polyethylene glycol) as first-line treatment 4
• If inadequate response, consider linaclotide 290 mcg once daily 1, 4

Review treatment efficacy after 3 months and discontinue ineffective medications rather than continuing indefinitely 1, 2

Third-Line Management: Specialized Dietary Intervention

If symptoms remain moderate-to-severe despite the above measures:

Refer to a specialist gastroenterology dietitian for a low FODMAP diet delivered in three phases (restriction, reintroduction, personalization) 1, 4

Important caveats:

• Screen for eating disorders before recommending restrictive diets 4
• Avoid FODMAP diet in patients with eating pathology, severe mental illness, or those already avoiding multiple food groups 3, 1
• The dietitian should assess for nutrition red flags: unintentional weight loss ≥5%, avoidance of multiple food groups, or nutrient deficiency 3

When to Refer

To Gastroenterologist:

• If diagnosis is in doubt or symptoms are refractory to primary care treatment after 12 months 1, 2

To Dietitian:

• Patient reports considerable intake of trigger foods 3
• Patient requests dietary modification advice 3, 2
• Presence of dietary deficits, nutritional deficiency, or unintended weight loss 3

To Gastropsychologist:

• Moderate-to-severe symptoms refractory to pharmacological treatment for 12 months 3, 2
• Consider cognitive behavioral therapy or gut-directed hypnotherapy at this stage 3, 2

Special Considerations for Adolescents

Given the patient's age (16 years), be particularly attentive to:

• Psychosocial factors: Assess for anxiety, depression, or stress related to school, social relationships, or family dynamics 3
• Eating behaviors: Screen for disordered eating patterns, as up to 25% of IBS patients have disordered eating 3
• Self-management skills: Provide age-appropriate education resources (apps, websites) to promote empowerment and self-efficacy 3