What is the most likely cause of a 72-year-old male's abdominal pain, loose and greasy stools, and weight loss, with a history of heavy alcohol use and smoking?

Chronic Pancreatitis with Exocrine Pancreatic Insufficiency

This patient most likely has exocrine pancreatic insufficiency (EPI) secondary to alcohol-induced chronic pancreatitis, and the most likely additional finding would be a low fecal elastase level (<100 mg/g of stool).

Clinical Reasoning

This 72-year-old male presents with the classic triad of chronic pancreatitis: chronic epigastric pain with episodic acute exacerbations, steatorrhea (loose and greasy stools indicating fat malabsorption), and weight loss 1, 2. The gradual onset over 2-3 years is characteristic of the progressive nature of chronic pancreatitis, where EPI typically develops after 5-10 years of disease 1.

Key Risk Factors Present

• Heavy alcohol use: Alcohol is responsible for 60-70% of chronic pancreatitis cases and is the most common etiology 1, 2, 3
• Smoking history: An independent risk factor that may account for 25-30% of cases and accelerates disease progression 2
• Macrocytosis on CBC: Consistent with chronic alcohol abuse and potential folate/B12 deficiency from malabsorption 1

Why Normal Lipase Doesn't Exclude Chronic Pancreatitis

The normal lipase level is actually expected in chronic pancreatitis with EPI. Unlike acute pancreatitis, chronic pancreatitis results in progressive destruction of pancreatic tissue, so serum enzyme levels are typically normal or even low because there is insufficient functional tissue to release enzymes 1. This is a critical pitfall—clinicians often mistakenly believe normal pancreatic enzymes rule out pancreatic disease, but in chronic pancreatitis with advanced exocrine insufficiency, this is the expected finding 1.

Most Likely Additional Finding: Low Fecal Elastase

Fecal elastase <100 mg/g of stool is the most appropriate initial test and provides good evidence of EPI 1. This test must be performed on a semi-solid stool specimen (not liquid diarrhea, which can give false-positive results) 1. Levels of 100-200 mg/g are indeterminate for EPI 1.

Why Fecal Elastase is the Answer

• EPI develops when more than 90% of pancreatic tissue is destroyed, resulting in maldigestion with steatorrhea 1
• The patient's greasy stools indicate fat malabsorption, which occurs earlier than protein malabsorption because lipase secretion is affected first 1
• Fecal elastase is the most widely available and practical indirect test for EPI in clinical practice 1

Other Expected Findings in This Patient

Nutritional Deficiencies

• Fat-soluble vitamin deficiencies (A, D, E, K) result from steatorrhea 1
• Calcium, magnesium, zinc, thiamine, and folic acid deficiencies are commonly reported 1
• The 10-pound weight loss reflects protein-calorie malnutrition from reduced intake (pain-induced anorexia) and malabsorption 1, 2

Metabolic Complications

• Risk of diabetes mellitus: Develops in 38-40% of chronic pancreatitis patients as insulin-producing beta cells are destroyed 2, 4
• Osteoporosis/osteopenia: Affects a significant proportion due to poor calcium/vitamin D absorption, low physical activity, and chronic inflammation 2

Imaging Findings

If cross-sectional imaging were performed, you would expect to see pancreatic calcifications, ductal dilatation, and atrophy on CT or MRI 4. However, these may be absent in earlier stages.

Management Implications

Once EPI is confirmed with low fecal elastase:

1. Initiate pancreatic enzyme replacement therapy (PERT): Start with 40,000-50,000 units of lipase per meal (500 units/kg/meal) and 20,000-25,000 units per snack (250 units/kg/snack) 1

2. Alcohol and smoking cessation: Absolutely critical—alcohol abstinence is essential and smoking accelerates disease progression 1, 2, 3

3. Nutritional supplementation: Fat-soluble vitamins (A, D, E, K), calcium, and other micronutrients as deficiencies are identified 1

4. Pain management: Analgesics before meals can reduce postprandial pain and improve food intake 1

5. Screen for diabetes: Given the 38-40% prevalence in chronic pancreatitis 4

Critical Pitfall to Avoid

Do not be falsely reassured by normal serum lipase or amylase levels in a patient with chronic symptoms suggestive of chronic pancreatitis. These enzymes are typically normal or low in advanced chronic pancreatitis because of pancreatic tissue destruction 1. The diagnosis relies on clinical presentation, risk factors (alcohol, smoking), and functional testing (fecal elastase) or imaging findings 1, 4.