What investigations are appropriate for a patient with hyperlipasemia and no abdominal pain, on mepolizumab (anti-interleukin-5 antibody) and methotrexate (antifolate) for severe asthma and atopic dermatitis?

Investigation of Mildly Elevated Lipase in a Patient with Severe Asthma and Atopic Dermatitis on Mepolizumab and Methotrexate

For a 40-year-old woman with severe asthma and atopic dermatitis on mepolizumab and methotrexate who has a mildly elevated lipase level without abdominal pain, a limited workup is appropriate, focusing primarily on medication-related causes rather than pursuing extensive pancreatic imaging.

Initial Assessment

• Confirm the lipase elevation (how many times above upper limit of normal)
• Review medication history, particularly timing of methotrexate administration
• Assess for other potential symptoms:
  • Nausea or vomiting
  • Changes in bowel habits
  • Weight loss
  • Fatigue

Recommended Investigations

First-line investigations:

• Repeat lipase level in 1-2 weeks
• Complete metabolic panel including:
  • Liver function tests (AST, ALT, alkaline phosphatase, bilirubin)
  • Renal function (BUN, creatinine)
  • Serum triglycerides
• Complete blood count with differential (including eosinophil count)

Consider if lipase remains elevated:

• Amylase level (to determine if isolated lipase elevation)
• Abdominal ultrasound (if lipase continues to rise or symptoms develop)

Clinical Context and Rationale

Medication Considerations

1. Methotrexate:

   • Can cause liver enzyme abnormalities in 20% of patients 1
   • Monitoring of liver function is recommended during therapy
   • Transient elevations in liver enzymes may occur without clinical significance

2. Mepolizumab:

   • Anti-IL-5 antibody primarily used for eosinophilic conditions
   • No direct association with pancreatic enzyme abnormalities in literature
   • Used in severe asthma and eosinophilic granulomatosis with polyangiitis (EGPA) 1

Differential Diagnosis for Isolated Lipase Elevation

Isolated lipase elevation (with normal amylase) is often not indicative of acute pancreatitis 2. Common causes include:

• Medication effects
• Renal insufficiency
• Delayed blood withdrawal after meals
• Hypertriglyceridemia
• Subclinical inflammatory processes
• Non-pancreatic sources of lipase (certain malignancies)

Management Approach

1. Continue current medications unless clinical symptoms develop or significant enzyme elevations occur

2. If lipase continues to rise:

   • Consider temporary dose reduction of methotrexate
   • Evaluate timing of blood draws (preferably fasting)

3. If symptoms develop or significant elevation occurs:

   • Consider more extensive imaging (CT abdomen)
   • Gastroenterology consultation

Important Considerations

• Isolated lipase elevation without abdominal pain is unlikely to represent clinically significant pancreatitis 2
• Methotrexate can cause transient liver enzyme elevations that often resolve without intervention 1, 3
• Avoid unnecessary imaging or invasive procedures in the absence of symptoms
• Consider the timing of blood draws in relation to meals and medication administration

Follow-up Recommendations

• Repeat lipase and liver function tests in 1-2 weeks
• Continue monitoring during regular follow-up visits for asthma and atopic dermatitis management
• Document trend of lipase values over time to establish pattern

This approach balances the need to identify potentially serious conditions while avoiding unnecessary testing in an asymptomatic patient with only mildly elevated lipase.