Elevated Liver Function Tests and Pasty Stool
Elevated liver function tests do not directly cause pasty stool, but both can be manifestations of the same underlying cholestatic liver disease—specifically, when bile flow is impaired, leading to fat malabsorption and pale, greasy (pasty) stools.
Understanding the Relationship
Elevated LFTs themselves are simply biochemical markers of liver cell injury or bile flow obstruction—they don't cause symptoms 1. However, when the pattern of LFT elevation is cholestatic (elevated alkaline phosphatase, GGT, and/or direct bilirubin more than ALT/AST), this indicates impaired bile flow into the intestine 2, 3.
The key mechanism: When bile cannot reach the intestine due to biliary obstruction or cholestatic liver disease, fat digestion and absorption are impaired, resulting in steatorrhea—pale, greasy, bulky, foul-smelling stools that may appear "pasty" 2.
Clinical Approach to This Presentation
Identify the Pattern of LFT Elevation
- Cholestatic pattern (ALP and GGT elevated >> ALT/AST) suggests bile flow problems and is the pattern most likely associated with steatorrhea 1, 3
- Confirm hepatic origin of elevated alkaline phosphatase by checking GGT 1, 4
- Check direct (conjugated) bilirubin—elevation suggests cholestasis or biliary obstruction 2
Determine the Cause of Cholestasis
Immediate imaging is essential to distinguish extrahepatic (biliary obstruction) from intrahepatic cholestasis 2, 4:
- Abdominal ultrasound is the first-line imaging to evaluate for biliary dilation, gallstones, masses, or bile duct obstruction 2, 3
- If ultrasound is inconclusive but clinical suspicion for biliary obstruction remains high (especially with abdominal pain, jaundice, or fever), proceed to MRCP to detect choledocholithiasis, biliary strictures, or obstruction 2
Evaluate for Specific Cholestatic Diseases
When cholestatic LFT pattern is confirmed, consider 2:
- Primary biliary cholangitis (PBC)
- Primary sclerosing cholangitis (PSC)
- Drug-induced cholestasis
- Infiltrative liver disease
- Biliary obstruction from stones or strictures
Common Pitfalls to Avoid
Do not assume normal LFTs exclude liver disease—liver disease can develop silently, and tests may remain normal until complications arise 1. Conversely, do not over-interpret isolated mild LFT elevations—30% of routine LFTs show at least one abnormal value, but only 3.9% of patients with abnormal ALT/AST are diagnosed with significant liver disease within 5 years 1.
The pattern matters more than absolute values for guiding your differential diagnosis 1, 3. A hepatocellular pattern (ALT/AST >> ALP) would not typically cause pasty stool, as this reflects liver cell injury rather than bile flow obstruction 3.
When to Refer
Refer to gastroenterology or hepatology when 5, 3:
- Persistent cholestatic pattern without clear cause
- Evidence of biliary obstruction on imaging requiring intervention
- Signs of advanced liver disease (jaundice, coagulopathy, hypoalbuminemia)
- Suspected autoimmune cholestatic disease requiring specialized management