Serum type III procollagen peptide, dynamic liver function tests and hepatic fibrosis in psoriatic patients receiving methotrexate.

The serum level of the aminoterminal peptide of type III procollagen (P3NP) was measured in 51 psoriatic patients on long-term, once weekly, low-dose methotrexate and in a control group of patients with extensive psoriasis who had never had systemic treatment. Serum P3NP levels were normal in all control patients, but were elevated in the majority of methotrexate-treated patients, even those with normal or non-specific liver histology. Although the highest P3NP values were found in the groups of patients with fibrosis and cirrhosis, isolated P3NP measurements did not discriminate between individuals with and without significant liver pathology. Neither standard nor dynamic liver function tests were able to identify patients with significant liver damage and in most cases results were in the normal range.