How to diagnose liver disease in patients with psoriasis?

Diagnosing Liver Disease in Patients with Psoriasis

The diagnosis of liver disease in psoriasis patients requires regular monitoring with serum aminoterminal peptide of procollagen III (PIIINP), liver function tests (LFTs), and non-invasive imaging techniques such as transient elastography, as standard LFTs alone are inadequate for detecting hepatic fibrosis. 1

Risk Assessment and Initial Evaluation

Patients with psoriasis have a higher risk of liver abnormalities compared to the general population, with approximately 24% developing liver enzyme abnormalities 2. The initial evaluation should include:

• Baseline laboratory tests:

  • Complete blood count (CBC)
  • Liver function tests (LFTs)
  • Renal function tests
  • Serum PIIINP (for patients on methotrexate)
  • Hepatitis B and C screening in patients with risk factors 3

• Risk factor assessment:

  • Obesity and waist circumference (strong predictor of liver fibrosis) 4
  • Diabetes mellitus (12.7 times higher risk of significant fibrosis) 4
  • Alcohol consumption
  • Dyslipidemia
  • Medications (particularly methotrexate)
  • Psoriatic arthritis

Diagnostic Algorithm

Step 1: Laboratory Monitoring

• Perform baseline LFTs and PIIINP before starting systemic therapy 1
• Monitor LFTs every 3-4 months in stable patients 3
• For patients on methotrexate, measure PIIINP every 3 months 1, 3
• Schedule laboratory tests 1-2 days before the weekly methotrexate dose to avoid transient elevations 3

Step 2: Interpret Laboratory Results

• For elevated LFTs:

  • If AST/ALT < 2× upper limit of normal: continue monitoring
  • If AST/ALT 2-3× upper limit of normal: withhold/decrease dose of methotrexate and consider gastroenterology referral 1
  • If AST/ALT > 3× upper limit of normal despite dose reduction: discontinue methotrexate 3

• For PIIINP (in patients on methotrexate):

  • Refer for specialist assessment if:
    • PIIINP > 8 mg/L on two occasions
    • Three measurements > 10 mg/L in a 12-month period
    • Single measurement > 10 mg/L 1

Step 3: Non-invasive Imaging

• Transient elastography (FibroScan):

  • Measures liver "stiffness" using ultrasound pulse
  • Highly sensitive and specific for detecting hepatic fibrosis
  • May be technically difficult in patients with obesity 1
  • Consider for patients with:
    • Persistently elevated LFTs
    • Abnormal PIIINP values
    • Multiple risk factors for NAFLD

• Ultrasound:

  • Screen for hepatic steatosis (found in 52.6% of psoriasis patients in one study) 5
  • If steatosis is identified, proceed to transient elastography

• Magnetic Resonance Elastography (MRE):

  • Consider for patients who are not candidates for transient elastography (e.g., severe obesity)
  • More accurate overall but more expensive 1

Step 4: Liver Biopsy

• Not recommended for routine monitoring of methotrexate hepatotoxicity 1
• Consider only when:
  • Non-invasive tests are inconclusive
  • Conflicting results between different diagnostic modalities
  • Suspicion of alternative liver pathology

Common Liver Conditions in Psoriasis Patients

1. Drug-induced liver injury (57% of cases) 2

   • Most commonly from methotrexate
   • Usually reversible with medication adjustment

2. Non-alcoholic fatty liver disease (NAFLD) (22% of cases) 2

   • More prevalent in psoriasis patients
   • Associated with metabolic syndrome
   • May progress to fibrosis and cirrhosis

3. Viral hepatitis

   • Most common liver disease (62.1%) in psoriasis patients according to Malaysian Psoriasis Registry 6
   • Screen before starting immunosuppressive therapy

4. Cirrhosis

   • Reported in 0.8% of psoriasis patients 2
   • Can limit therapeutic options

Special Considerations and Pitfalls

• Methotrexate monitoring: Standard LFTs are only 38% sensitive and 83% specific for detecting hepatic fibrosis, making PIIINP measurement crucial 1

• False positives with PIIINP: Values may be elevated due to:

  • Active bone remodeling
  • Orthopedic surgery
  • Skeletal fractures
  • Erosive psoriatic arthritis
  • Growth in children 1

• Timing of tests: Avoid measuring LFTs within 1-2 days after methotrexate administration to prevent detecting transient elevations 3

• Medication interactions: Be aware that NSAIDs and trimethoprim-sulfamethoxazole can increase methotrexate toxicity and affect liver function 3

• Comorbidity management: Patients with psoriasis and liver disease have higher rates of metabolic syndrome components (dyslipidemia 27.5%, hypertension 33.9%, diabetes 22.4%) that require management 6