What is the appropriate management for a patient presenting with abdominal pain, weight loss, and hyperpigmentation after a holiday?

Immediate Evaluation for Adrenal Insufficiency (Addison's Disease)

This patient requires urgent evaluation for primary adrenal insufficiency (Addison's disease), given the classic triad of abdominal pain, weight loss, and hyperpigmentation following travel—the hyperpigmentation ("tanner than usual") is the critical diagnostic clue that distinguishes this from other causes of abdominal pain.

Initial Diagnostic Workup

Immediate Laboratory Testing

• Draw morning cortisol and ACTH levels before any treatment to establish baseline adrenal function 1
• Screen for hypothyroidism, diabetes, and electrolyte abnormalities (hyponatremia, hyperkalemia are hallmarks of adrenal insufficiency) 1
• Obtain complete blood count, basic metabolic panel, and assess for hypoglycemia 1
• Check for eosinophilia, which commonly accompanies adrenal insufficiency 1

Travel-Related Infectious Considerations

• Given recent travel, specifically evaluate for tropical sprue and parasitic infections (particularly Giardia), which can present with abdominal pain, weight loss, and malabsorption 1
• Obtain stool studies including PCR for Giardia and specific immunoassays 1
• Consider testing for tuberculosis with interferon-gamma release assay if travel was to endemic areas, as TB can cause both adrenal insufficiency and intestinal pathology 1

Critical Clinical Assessment

History and Physical Examination Priorities

• Document the exact pattern and timing of abdominal pain, relationship to eating, and quantify weight loss (percentage over specific time periods: 2 weeks, 3 months, 6 months) to calculate BMI and severity 1
• Examine for orthostatic vital sign changes (lying to standing pulse and blood pressure), which indicate volume depletion or autonomic dysfunction 1
• Assess for other signs of adrenal insufficiency: fatigue, salt craving, postural dizziness, nausea/vomiting 1
• Obtain detailed medication history, particularly NSAIDs, opioids, and anticholinergics that could contribute to symptoms 1

Imaging to Exclude Mechanical Obstruction

• Obtain CT abdomen with oral and IV contrast to exclude mechanical obstruction, mesenteric ischemia, or other structural pathology 1
• This is essential before attributing symptoms solely to adrenal insufficiency or functional disorders 1

Differential Diagnosis Framework

Primary Considerations Based on Clinical Presentation

Adrenal Insufficiency (Addison's Disease) is the leading diagnosis given hyperpigmentation with abdominal pain and weight loss. The hyperpigmentation results from elevated ACTH stimulating melanocytes and is pathognomonic when combined with these symptoms 1.

Chronic Mesenteric Ischemia should be considered in patients with cardiovascular disease presenting with abdominal pain and weight loss, though hyperpigmentation would be atypical 1. This typically presents as postprandial pain causing food aversion 1.

Tropical Sprue or Parasitic Infection given recent travel, presenting with diarrhea, abdominal pain, weight loss, and potential vitamin B12/folate deficiency causing hyperpigmentation 1.

Seronegative Enteropathy including celiac disease variants, autoimmune enteropathy, or infectious enteritis should be evaluated if initial workup is negative 1.

Secondary Investigations if Initial Workup Negative

• Perform ACTH stimulation test if morning cortisol is equivocal 1
• Screen for autoimmune conditions: ANA, anti-tissue transglutaminase for celiac disease 1
• Consider upper endoscopy with duodenal biopsies if malabsorption suspected 1
• Evaluate for connective tissue disorders (anti-centromere, anti-Scl70) and paraneoplastic syndromes if dysmotility suspected 1

Critical Management Priorities

Immediate Actions

• If adrenal crisis is suspected (hypotension, severe electrolyte abnormalities), initiate IV hydrocortisone immediately without waiting for test results 1
• Correct any coagulopathy or severe electrolyte disturbances 1
• Begin nutritional assessment and consider refeeding syndrome risk if severely malnourished 1

Common Pitfalls to Avoid

• Do not dismiss hyperpigmentation as simply "sun tan"—this is a critical diagnostic sign when combined with constitutional symptoms 1
• Do not delay cortisol testing by starting empiric steroids unless the patient is hemodynamically unstable 1
• Avoid attributing all symptoms to functional disorders without excluding organic pathology with imaging 1
• Do not rely solely on normal laboratory values to exclude serious pathology—clinical judgment and imaging are paramount 2, 3

Algorithmic Approach

1. Stabilize hemodynamics and draw cortisol/ACTH if stable 1
2. Obtain CT abdomen to exclude surgical emergencies 1
3. Send infectious workup based on travel history 1
4. Initiate treatment for adrenal insufficiency if confirmed, or treat identified infectious/structural cause 1
5. Reassess within 12-24 hours if diagnosis remains unclear and symptoms persist 4, 2