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Use of amino terminal type III procollagen peptide (P3NP) assay in methotrexate therapy for psoriasis
S Khan1, D Subedi, M M U Chowdhury
1Department of Immunopathology, St Bartholomew's Hospital, London, UK. sujoykhan@aol.com
Abstract:
Hepatic fibrosis continues to be a risk in patients receiving methotrexate for psoriasis. Measurement of amino terminal levels of type III procollagen (P3NP) has been advocated as an effective non-invasive test for ongoing hepatic fibrogenesis that could avoid liver biopsies. An audit was conducted to assess the practice of P3NP monitoring using guidelines produced by Manchester and whether the agreed levels correlate with histological severity. Sixty five patients with 174 P3NP assays and 30 liver biopsies were reviewed between the years 1999 and 2003. Total number of patient-methotrexate years was 278.9 and the mean cumulative dose of methotrexate received was 2000 (SD 1838) mg. A higher cumulative dose of methotrexate correlated significantly with high mean and maximum P3NP levels. Of the 30 liver biopsies, 26 (86.6%) showed normal histology or mild to moderate steatosis, three had focal fibrosis, and one had early cirrhosis. A median P3NP value of 5.8 mug/l or higher had a stronger correlation with histological severity. It is concluded that P3NP assay is a valuable adjunct to the clinical management of patients receiving long term methotrexate that can avoid or reduce unnecessary liver biopsies.
Insights
Amino terminal type III procollagen (P3NP) monitoring helps manage methotrexate therapy for psoriasis patients. This non-invasive test correlates with liver fibrosis severity, potentially reducing the need for liver biopsies.
Area of Science:
- Dermatology
- Hepatology
- Clinical Chemistry
Background:
- Methotrexate therapy for psoriasis carries a risk of hepatic fibrosis.
- Liver biopsies are invasive and may be avoided with non-invasive markers.
- Amino terminal type III procollagen (P3NP) is a proposed marker for hepatic fibrogenesis.
Purpose of the Study:
- To audit the practice of P3NP monitoring in methotrexate-treated psoriasis patients.
- To assess the correlation between P3NP levels and histological liver severity.
- To evaluate P3NP's utility in reducing liver biopsies.
Main Methods:
- Retrospective audit of 65 patients with 174 P3NP assays and 30 liver biopsies (1999-2003).
- Analysis of patient-methotrexate exposure (278.9 patient-years) and cumulative methotrexate dose.
- Correlation analysis between P3NP levels, methotrexate dose, and liver biopsy findings.
Main Results:
- Higher cumulative methotrexate doses correlated significantly with elevated mean and maximum P3NP levels.
- A median P3NP value of ≥5.8 μg/l showed a stronger correlation with histological severity.
- Most liver biopsies (86.6%) showed normal histology or mild steatosis; only 4/30 indicated fibrosis or cirrhosis.
Conclusions:
- P3NP assay is a valuable non-invasive tool for monitoring hepatic fibrogenesis in psoriasis patients on long-term methotrexate.
- P3NP monitoring can help avoid or reduce the frequency of unnecessary liver biopsies.
- Clinical practice guidelines for P3NP monitoring should consider correlation with histological severity.
