Investigations

Liver function tests: (1)

• raised serum alkaline phosphatase
• raised serum aspartate aminotransferase in 90% of cases (markedly elevated levels - more than 5 times the upper limit of normal - may suggest an overlap with autoimmune hepatitis)
• raised serum bilirubin levels in many patients

Other features: (2)

• hypergammaglobulinaemia occurs in one third; IgM levels increased in 50% of cases
• raised hepatic copper levels in nearly 90% of cases
• autoantibodies are less frequent than in autoimmune chronic active hepatitis and primary biliary cirrhosis:
  • smooth muscle antibodies occur in 11% of cases
  • P-ANCA positive in more than 50% of cases
  • antinuclear antibodies in 6 to 35% of cases
  • antimitochondrial antibodies almost never occur

Liver biopsy is generally not necessary when typical imaging findings are present, but may reveal:

• a fibrous obliterating cholangitis
• loss of interlobular and adjacent septal bile ducts

(For non-invasive assessment of fibrosis, transient elastography and magnetic resonance elastography are increasingly used for risk stratification and longitudinal monitoring, particularly given the limitations of liver biopsy in PSC due to its patchy fibrotic distribution.) (3)

MRCP is the preferred diagnostic modality due to its non-invasive nature and comparable sensitivity and specificity to ERCP. In contrast, ultrasound and computed tomography (CT) lack diagnostic utility for PSC. (4)

Reference

1. Kalas MA, Chavez L, Leon M, Taweesedt PT, Surani S. Abnormal liver enzymes: A review for clinicians. World J Hepatol. 2021 Nov 27;13(11):1688-1698.
2. Singh S, Talwalkar JA. Primary sclerosing cholangitis: diagnosis, prognosis, and management. Clin Gastroenterol Hepatol. 2013 Aug;11(8):898-907
3. Sirpal S, Chandok N. Primary sclerosing cholangitis: diagnostic and management challenges. Clin Exp Gastroenterol. 2017;10:265-273
4. Morgan MA et al. Primary sclerosing cholangitis: review for radiologists. Abdom Radiol (NY). 2023 Jan;48(1):136-150.